* DATE DUE j 14 1 P 2007 Special Elditioi^ members of the National Fire Protection Association mr m INCORPORATED 1901 ESTABLISHED AND MAINTAINED BY THE National Board of Fire Underwriters FOR SERVICE— NOT PROFIT a Report on INTERIOR BUILDING CONSTRUCTION m Consisting of METAL LATH AND GYPSUM PLASTER ON WOOD SUPPORTS Jointly submitted by Associated Metal Lath Manufacturers, Chicago, 111. and National Lumber Manufacturers Association, Chicago, 111. Washington, D. C. Report on Interior Building Construction Consisting of Metal Lath and Gypsum Plaster on Wood Supports Jointly Submitted by Associated Metal Lath Manufacturers Chicago, 111. and ' { National Lumber Manufacturers Association Chicago, 111. Washington, D. C. ESTABLISHED AND MAINTAINED BY THE National Board of Fire Underwriters FOR SERVICE— NOT PROFIT PRINCIPAL OFFICE AND TESTING STATION 207 East Ohio Street, CHICAGO, ILL. Aug. 10, 1922 Retardant No. 1355 Copyright 1922, by Underwriters’ Laboratories ■JvS i Mor. '7''' C-' t PREFACE The investigation described herein was inaugurated and largely carried out by the late W. C. Robinson, Vice-President and for 20 years, Chief Engineer of Underwriters’ Laboratories. The signer of this report and others of Mr. Robinson’s associ- ates in the staff desire, in presenting the report, to acknowledge his large share in the work it describes. Mr. Robinson, for sev- eral years before his death (July 31, 1921), had in mind the feasibility of designing buildings of frame and of ordinary con- struction, especially those intended for residence and similar light occupancies, where only the common fire hazards are found and where the bulk of the inflammable contents is small, so that they would be semi-fire-resistive. It was his sincere belief that utilization of suitable, readily available materials and methods of design was not only possible but entirely practicable and this without material additional cost of buildings and without a need for educating the American people to live or work under new or strange conditions. When economic considerations do not require or justify fire resistive construction throughout, the ap- plication of a certain few fundamentals of fire protection will do much to reduce the large cost in life and in property of the present national fire waste, (approx. 20,000 lives and $500,000,- 000.00 annually). One such fundamental is to confine incipient fire to the room or other space of its origin. The use of ma- terials and methods having a definite classification as Fire Re- tardants, (such as the constructions described herein and others now rated, or presently to be rated) when they are selected according to the probable severity 6f fire exposure, is a logical means of observing this fundamental. I TABLE OF CONTENTS Page INTRODUCTORY 1 SECTION I Walls and Partitions, Bearing and Non-Bearing DESCRIPTION 4 General Character 4 Use 5 Description of Parts ! 6 PLAN OF INVESTIGATION 8 EXAMINATION AND TEST RECORD 9 Installation Test 9 _ Fire Endurance Test No. 1 14 Fire Endurance Test No. 2 23 - Fire and Hose Stream Test 34 Supplemental Fire and Hose Stream Tests 41 SECTION II Floor and Ceiling Construction DESCRIPTION 46 General Character 46 Use 47 Description of Parts 47 PLAN OF INVESTIGATION 47 EXAMINATION AND TEST RECORD 48 Installation Tests 49 Fire Endurance Test 57 Fire and Hose Stream Test 62 Excess Load Test.„ 64 SECTION III SERVICE RECORD 67 SUPERVISION OF PRODUCT BY UNDERWRITERS’ LABORATORIES 67 CONCLUSIONS 67 Practicability 67 Durability 68 Strength 68 Fire Retarding Properties 69 TABLE OF CONTENTS— Continued SECTION IV Pa^e APPENDIX I 74 Tests on Wood Joist Floor Construction — Finished with Metal Lath and Portland Cement Plaster 74 APPENDIX II 94 Transverse Load Tests on Metal Lath and Gypsum Plaster on Wood Supports 94 APPENDIX III 96 Specifications for Preparation and Installation of Metal Lath and Gypsum Plaster on Wood Supports 96 APPENDIX IV : ’ 100 Claims Made by Submittors 100 Principle of Design 100 Durability 102 Economies 103 Safety After Charring 104 Minimum Metal Lath Specifications 105 APPENDIX V 106 Standard Equipment and Panels for Partition Tests 106 APPENDIX VI : 110 Standard Equipment for Tests of Floors and Ceiling Finish 110 APPENDIX VII 113 Standard Specifications for Fire Tests of Materials and Con- struction 113 SECTION V RECOMMENDATIONS 117 ■4.’ Digitized by the Internet Archive, in 2017 with funding from University of Illinois Urbana-Champaign Alternates / / https://archive.Org/details/repOrtOninteriorOOunde AOCNCII E-PRESIOENTS, W H MERRILL. President DANA PIERCE. U A R SMALL. i D B. ANDERSON, secretary L B HEADEN. Treasurer CHICAGO. NEW YORI- M yV) BOSTON, e (\VV INCORPORATED 1901 ^ established AND MAINTAINED BYTHE CHICAGO. 207 East Ohio Strcet NEW YORK. 25 CitV Haul Place BOSTON. 67 Milk STueeT PITTSBU RGH. 324 Pourth Avenue SAN FRANCISCO ESTABLISHED AND MAINTAINED BYTHE National Boari) of5in» UnDcnpritmi FOR SERVICE-NOT PROFIT 207 EAST OHIO STREET. CHICAGO Retardant No. 1355 August 10, 1922 Report on INTERIOR BUILDING CONSTRUCTION consisting of Diamond Mesh Expanded Metal Lath and %-in. (three-caat) Fibered or Sanded Gypsum Plaster, mounted on Wood Sup- ports, for Bearing and Non-Bearing Walls and Partitions and Wood Joist Floors in Buildings of Frame or Ordinary Con- struction suitably fire stopped. Associated Metal Lath Manufacturers and National Lumber' Manufacturers Association. Joint Submittors. INTRODUCTORY In 1918 the Associated Metal Lath Manufacturers, an or- ganization of a number of producers of metal lath, and the National Lumber Manufacturers Association, arranged for a series of tests at Underwriters’ Laboratories to determine the fire retarding value of a building construction utilizing the prod- ucts of the members of the two associations. A series of tests was first made, in which test results were secured which were judged not comparable to the best possible results obtainable with the submittors’ products. Accordingly, other tests were arranged and made in 1922 with samples in which either sanded or fibered gypsum plaster was used instead of portland cement 1 and sand plaster. It is largely upon the basis of the results of these later tests that the conclusions and recommendations of this report are drawn, although much valuable data was obtained in the first series of tests, the character and results of which are briefly outlined and illustrated- in Appendix I. In the autumn of 1921 the Fire Council of Underwriters’ Laboratories endorsed a recommendation of the Protection En- gineers to the effect that future work on fire retardants should be upon the basis of the Standard Specifications for Fire Tests of Building Materials and Construction regularly adopted as a tentative American Standard by the American Engineering Standards Committee. The test practices outlined in these standard specifications for fire tests are substantially those which have been employed by Underwriters’ Laboratories for a number of years. Accordingly, the classifications recommended at the conclusion of this report are based upon nationally stand- ardized test methods and also upon methods of analysis of re- sults practically identical with those employed in the classifica- tion of a long series of fire retarding devices, designs, and con- structions previously reported upon by Underwriters’ Labora- tories. These Standard Specifications for Eire Tests of Building Ma- terials and Construction are given in Appendix VII. This report deals with interior wood studded, bearing and non-bearing, walls and partitions and with a wood joist floor con- struction protected by expanded metal lath and gypsum plaster finish, developing mainly the fire retardant properties secured by the use of these materials. This report is divided into the following sections : SECTION I Interior building construction for bearing and non-bearing walls and partitions consisting of expanded metal lath and gyp- sum plaster on wood supports. SECTION II Interior floor and ceiling construction as a fire retardant consisting of expanded metal lath and gypsum plaster, on wood joists with wood, rough and finished flooring. SECTION III The conclusions drawn from the investigation and tests made as described in Sections I and II, together with statements as to Service Record and methods of follow-up applicable. 2 SECTION IV This part of the report consists of several appendixes, as follows : Appendix I — Wood joist floor construction protected by metal lath and portland cement plaster. Appendix II — Transverse Load Tests on wood studs pro- tected by metal lath and 'gypsum plaster construction. Appendix III — Specifications for application of metal lath and gypsum plaster construction on wood supports. Appendix IV — Claims made by the Submittors. Appendix V — Standard equipment and panels for tests of wall and partition constructions. Appendix VI — Standard equipment for tests of floor and ceiling constructions. Appendix VII — Standard Specifications for Fire Tests of Materials and Construction. SECTION V The recommendations made by the Staff to the Fire Council of Underwriters’ Laboratories covering classification and list- ing of the constructions reviewed. SECTION I Retardant No. 1355 INTERIOR BUILDING CONSTRUCTION FOR Bearing and Non-Bearing Walls, and Partitions consisting of Metal Lath and Gypsum Plaster on Wood Supports INTERIOR FINISH FOR WALLS AND PARTITIONS AS A FIRE RETARDANT As regards its influence on the spread of fire within build- ings, interior wall and partition finish should possess fire re- sistive properties providing a barrier to the spread of fire within buildings and preserving the structural integrity of buildings under fire conditions, and should retain these properties under the wear and tear and other service conditions incidental to the use of buildings. These requirements necessarily involve all of the parts that are assembled to finish or to ef¥ect the subdivi- sion of buildings and their floor areas into the units required by the occupancy, including the frames, doors and sash at necessary openings. This report deals with the solid or unbroken portions of partitions or walls, bearing and non-bearing, of representative metal lath and gypsum plaster construction on wood studs, de- veloping mainly the fire retardant properties secured by the use of these materials. DESCRIPTION: GENERAL CHARACTER The construction forming the subject of this section of the report consists of bearing and non-bearing room and corridor partitions of the hollow type and wood stud, metal lath and fibered gypsum plaster pattern. Th_ese partitions or walls consist of the studs, the sills, or foot plates, the cap plates, the fire stops, the frames, the trusses, the doors, the sash, the metal lath, its fastenings, the special supports, the plaster coatings, the grounds, the metal corner beading and the standing finish that may be used on the sur- 4 DESCRIPTION - w^.[TI faces. The construction is approximately 5 in. or 7 in. in thickness, depending on the size of the studs, and may be made oi any length and in heights up to and including 25 ft. The average height does not exceed 12 ft. In plain constructions the wood studs are spaced 12 or 16 in. on centers and are so arranged at the corners and at junctions between partitions and with walls that solid corners and angles are provided for attaching the lath at these points. In curved constructions the studs are set and spaced according to the radius of curvature. They are doubled around all openings. The studs extend from the sills at the floor, or from girders, or from the plates of' partitions or walls directly underneath to the cap plates at the top. The sills and plates extend across the studs at the bottom and top, respectively. The sills rest on the under or rough floor and are used when the studs do not extend through the floor joist and rest on girders or the plates directly underneath. The fire stops are located between the studs at floor levels. The trusses are employed in bearing constructions and are used above openings in excess of 3 ft. in width and where unusual loads come over the opening. The frames for the doors and sash are centered in the studding and are nailed to studs. The sheets of lath, on each side of the studding are fastened with staples or with nails driven part way in and bent over to the studs or supports and are placed in horizontal courses with edges overlapping. At joints with side walls and ceilings the lath is bent to a right angle and extended to overlap the ad- joining surface for about 6 inches. A tie wire is used at over- lapping edges of the lath between supports and in attaching the lath at coves. Special supports are used at coves, for extra nailing bases wherever the framing is irregular and at fixture outlets. The plaster coatings completely cover all lathed surfaces and extend to the floors and back of all standing finish up to the rougher framing at the openings. The grounds are nailed to the framing at the openings and cemented to the scratch coat of plaster at other points. The metal corner beading is nailed to the vertical supports at outside angles. The standing finish is nailed to the grounds and supports and is in direct contact with the plastered surfaces where it is applied. USE This construction is regularly used for bearing and non- bearing partitions of walls in buildings in which wood studding is employed and for studded exterior walls except for the ex- terior finish. It is also used on masonry walls where furring is employed. 5 WALLS AND PARTITIONS DESCRIPTION OF PARTS Studs — The studs may be of any wood used in buildings of frame or ordinary construction that is sound and free from de- fects that seriously affect alignment of the studs or impair their strength or durability. The studs are usually nominally 2 by 4 in., but they may be 2 by 2 in., 2 by 6 in. or larger. The size of the studs and their spacing is largely dependent on the loads, the heights and the location of openings. Sills and Plates — The sills and plates are usually made of the same size and kind of wood as the studs. Single sills and l)lates are usually employed for non-bearing construction. Dou- ble sills and plates may be used for bearing partitions or walls. Fire Stops — Fire stops at the floor levels may consist of metal lath baskets filled with incombustible materials and com- pletely filling the spaces between joists and studs to a height of 4 in. above the floor level or may be tightly fitted wood blocks with a nominal thickness of 2 in. or more. The wooden braces or bridging between studs at the middle of the studs serve as fire stops as well as to increase the stability or lateral stiffness of the assembly. Trusses — The trusses are mostly used in bearing partitions and walls, are made of the same size and kind of wood as the studs, and consist of diagonal struts between the plates and the heads of the framing at openings. They are used to transmit the loads to the double stud supports at the sides of the openings. The studs are cut in between the diagonals over the opening. Frames, Doors and Sash — These members may be made of any kind of^ seasoned wood and in any design used for interior finish. The frames are securely nailed to the double studs at the top and sides of the openings and are also held in place and finished by the casing on each side of the partitions. The doors and sash are mounted in the frames with ordinary hardware in the usual manner. When metal frames and doors and sash glazed with wired glass are employed in these partitions the metal members are installed and attached in essentially the same manner as the wooden members. Metal Lath — The lath is of the expanded metal type and the 'yg-in. diamond mesh pattern and is made from No. 26 U. S. gauge open hearth sheet steel. The finished sheets are 18 and 24 in. wide and 96 in. long, are coated with asphaltum paint and weigh 2.5 lbs. per sq. yd. The lath is furnished in bundles containing 9 to 15 sheets or 16 to 20 sq. yds. per bundle fof the 18 and 24-in. widths, re- spectively. ' ^ G DESCRIPTION Nails, Staples and Tie Wire — The nails, when used, are 4 penny l^^-in. nails and are driven partly in and bent over. The staples are 1^-in. No. 14 W. & M. gauge round top plain wire staples with pointed ends. The tie wire is No. 18 U. S. gauge soft annealed wire. V Plaster Coatings — The plaster coatings, aggregating about ^ in. in thickness, consist of a scratch coat and a brown coat of a standard brand of fibered or sanded gypsum plaster and sand, and a finish coat of lime putty gauged with gypsum plaster. The scratch coat is composed of one part by volume of gyp- sum plaster and one part by volume of clean, sharp, dry sand. The brown coat is composed of one part by volume of gypsum plaster and two parts by volume of clean, sharp, dry sand. The finish coat is composed of three parts lime putty by volume and one part by volume of dry calcined gypsum plaster. The outer surface of the plaster coatings is finished smooth and true. Grounds — The grounds consist of narrow wooden strips ^ in. thick at the framing around openings and standard round metal spot grounds at all other points. The spot grounds are of such thickness that their outer faces finish ^ in. from the supports and are provided with metal backing. Metal Corner Beading — The metal corner beading may be of any of the forms ordinarily employed for the protection of plas- ter corners at outside angles. Standing Finish — The standing finish may consist of any or all of the following items : baseboards, wainscoating, casings, chair rails, moulding or finished woodwork that is attached to the partitions after the plastering is completed. These mem- bers may be made of any kind of seasoned wood and be of any design used for interior finish, and are securely nailed to the grounds, studs or rougher framing. Where desired the standing finish may be of metal. INSTALLATION Complete specifications for preparation and application of metal lath and gypsum plaster construction on wood supports are given in Appendix III. CLAIMS MADE BY THE SUBMITTORS The claims as set forth by the submittors relative to this construction are given in Appendix IV. OBJECT OF THE INVESTIGATION: The object of this investigation was to ascertain from the fire protection viewpoint the value of the construction described 7 WALLS AND PARTITIONS and to determine its classification under the' ‘'Standard Specifi- cation for Fire Tests of Materials and Construction/’ as given in Appendix VII. PLAN OF INVESTIGATION: The general features of the investigation covered the sub- jects of Practicability, Durability, Strength and Uniformity as well as of Resistance to Fire and to Fire and Hose Streams. In considering these subjects the features of Handling and Shipping, Preparation for axid actual Installation, Maintenance, Wear and Tear, Moisture, Heat, Flame Resistance and Heat Resistance were severally studied. Data covering these features and properties were obtained during the preparation of speci- mens for tests, during the actual conduct of tests and in studies of the specimens and their units after tests. THE FOLLOWING TESTS WERE MADE Installation Test. Two Standard Fire Endurance Tests. Standard Fire and Hose Stream Test. Supplemental Fire and Hose Stream Tests. The procedures employed in these tests and the performance of the specimens in the tests are reported in the following sec- tion entitled Examination and Test Record. 8 EXAMINATION AND TEST RECORD: INSTALLATION TEST This test was made in connection with the installation of specimens in the panels for the Fire Endurance Tests and the Fire and Hose Stream Test. These panels and the frames in which they are mounted for tests are described in Appendix V hereto. Three test panels were installed in accordance with the method advocated by the Submittors and as detailed in Appen- dix III, Specifications for Preparation and Installation of Metal Lath and Gypsum Plaster Construction on wood supports. The following is a list of the material used in the installation of the panels and in supplementary tests. Bill of Material — • 5 bundles of No. 26 U. S. gauge ^-in. diamond mesh lath, sheets 24 in. wide and 96 in. long. 20 pounds of l^^-in. No. 14 W. & M. gauge wire staples, 6 pounds of No. 18-gauge soft annealed tie wire, 130 spot grounds, 8 bags of extra fibered gypsum plaster, 8 bags of hair fibered gypsum plaster,. 6 bags of regular fibered gypsum plaster, I bag of dry calcined gypsum plaster, 4 bags of hydrated lime, 3^ yards of plastering sand, 12 pieces of 9-in. Southern Yellow Pine baseboards, 12 pieces of 3^-in. Southern Yellow Pine chair rails, 12 pieces of 1^-in. Southern Yellow Pine picture moulding. METHODS The framework or studding was mounted .in the panel frames and the wood trim was applied by ex])erienced workmen of the Laboratories’ force. The Submittors furnished the work- men for installing the metal lath, the spot grounds, and the plaster coatings. The following observations and comments relate to the fea- tures and properties listed in the foregoing Plan of Investi- gation. RESULTS Preparation and Installation of Lath — The bundles of lath were opened and the sheets removed and carried to the panels by one man. The sheets required no special preparation except cutting to the proper length and bending to return on the ma- sonry at the side and upper edges of the panels. The bundles and sheets were easily handled. The sheets were cut by ordi- nary snips and bent over a straight edge without difficulty. 9 WALLS AND 'PARTITIONS The lath was applied to both sides of each of the panels by one lather. The sheets were placed in position in horizontal courses and attached by staples driven into the studs, beginning at the top. Each sheet was adjusted so that its upper edge overlapped the lower edge of the preceding sheet >4 to ^ in., was held in position by a few staples until in proper position at all points and then fastened by wire staples spaced 4 to 6 in. on each support. Each course consisted of one full sheet and a part of another. The edges and ends were bent so as to return on the brickwork from 2 to 6 in. at the sides and top and bottom of the panels, staples being driven into the mortar joints at 6 to 12-in. intervals. The vertical joints between the sheets were broken, lapped 1^ to 3 in. at the studs, and were held to- gether by the staples. The edges of the sheets at the hori- zontal joints were tied together between each stud by No. 18- gauge tie wire. The observations show that the lath can be properly cut, handled, fitted and attached to walls and partitions on the in- terior of buildings having wood furring and studding spaced 16 in. center to center, in the manner specified. The lath can be fitted, placed in proper position and attached without difficulty by workmen of ordinary experience, but care must be exercised in driving the staples into the supports. Nearly 50 percent of the staples were bent over and imperfectly driven in attaching the lath in these tests, suggesting the use of a heavier staple. With this exception the job probably represented good average work in all essential particulars. The lath was free from ex- cessive bulging at any point and was fairly rigid but could be bent inward between the studs to some extent under the pres- sure of the hand. Only the ordinary staging and tools were re- quired for the installation of the lath. Preparation and Application of Plasters — The plasters were delivered in bags and the sand in bulk, and were stored in a clean, dry place until used. The plaster of the scratch coat was prepared in an ordinary .nixing box, one end of which was slightly higher than the other. A layer of sand was placed in the box and then an equal volume of extra fibered gypsum plaster, this proportion being close to 100 lbs. of plaster to 150 lbs. of sand. The plaster and sand were then hoed from one end of the box to the other, until the dry mixture was uniform in color. Clean water was then placed in the lower end of the box and the dry mixture hoed into it until the plaster was uniformly mixed to the proper con- sistency for application. The plaster for the brown coat was prepared in the same way, one part of regular fibered gypsum plaster being used to 10 INSTALLATION TESTS two parts of sand by volume, this preparation being close to 100 lbs. of plaster to 300 lbs. of sand. The lime putty finish coat of plaster was prepared by form- ing a ring of lime putty about 6 in. high on a mortar board, placing about 4 in. of water in the ring, sifting the dry gypsum plaster into the water, and thoroughly mixing with the lime putty after the gypsum plaster had soaked for several minutes and had been mixed to a creamy consistency. One part of gyp- sum plaster was mixed with about three parts of lime putty by volume. The finish coat was mixed to a uniform paste ready for application. A thin coat of plaster was first applied to the lath on both sides of each of the panels. The plaster was applied lightly but with sufficient pressure to force it well through the mesh, imbed the metal and form full keys. Sufficient plaster was applied to thoroughly cover the lath on the plaster side. After the coat had set for a few minutes, the surface was thoroughly scratched in both directions with the edge of a piece of the metal lath. After the scratch coat had dried for about 18 hours, the brown coat was applied. Sufficient plaster was spread on to bring the coating out nearly flush with the grounds and the surfaces then made straight and true with a rod and darby but were left rough under the tools to furnish a bond for the finish coat. After the brown coat had dried for about five days, the lime putty finish coat was applied. The surface of the brown coat was first sprinkled slightly with clear water and a thin coat of the plaster then thoroughly troweled on, applying enough plas- ter to cover the brown coat completely. Enough additional plaster was then applied to make the wall straight and true. The surfaces were then gone over again with the material as thin as it could be handled and all imperfections worked out and the coating troweled to a smooth, uniform surface. The observations show that when ordinary facilities are pro- vided, these plasters can be properly handled and mixed by workmen reasonably familiar with this class of work. The mix- ing box must be tight and of ample size for the batches used. The workmen must understand the importance of obtaining the proper proportions, of prompt completion of the batch mixes, and of clean tools. The use of mixed plaster that has com- menced to set must be avoided. Application of Spot Grounds and Finish — After the scratch coats had become dry a row of spot grounds was installed at the points where the base boards, chair rails and picture mould- ings were to be attached. A layer of special gypsum plaster 11 WALLS AND PARTITIONS was spread on the scratch coats at the points where the grounds were to be located and the grounds at each end of each row pressed firmly into the gypsum until the outer faces of the grounds were ^ in. from the supports. Lines were then stretched between these grounds and the intermediate grounds set so that their outer faces were flush with the line. Rows of 6 or 7 grounds were employed at the chair rails and picture moulding, and rows of 8 at the base boards. The spacing be- tween the grounds varied from 143^ to in. The observations show that the spot grounds can be prop- erly installed by workmen who are familiar with the instruc- tions and who have had some experience in handling the gyp- sum plaster used in setting and in securing alignment. All of the spot grounds used were securely attached, located in a straight line, and fairly true in respect to their outer surfaces. They were installed by an experienced man but the observa- tions indicated that the work could be accomplished by work- men of ordinary experience. Baseboards, chair rails and picture mouldings were attached to each side of each pane. The baseboards were located at the bottom of the panels, the chair rails 36 in. above the bottom and the picture moulding 12 in. from the top of the panels. These members were attached by one or two long wire nails driven through the trim into each spot ground two nails being used in most cases. The trim was drawn close to the plaster surface in all cases and all grounds remained firm and secure, without injury to the plaster. The observations show that wood trim can be securely at- tached to the spot grounds used and that the trim can be made to fit closely to the finish if reasonable care is taken to obtain proper alignment of the grounds and true plaster surfaces be- tween the grounds. Maintenance — The observations during the construction of the panels indicate that the materials are of such a form and so arranged that injured portions of the finish can be readily re- paired or removed and replaced. The damaged plaster can be removed and replaced by new plaster and finished off flush with the uninjured plaster surfaces. In case of injuries, sufficiently extensive to rupture both the lath and the plaster, new lath can be attached to the old or extended back and attached to the supports and replastered. The staples and nails in the lath can be pulled out or new staples or nails installed in replacing the lath. The gypsum plasters will bond with the old and provide tight joints at the junctions thus formed. 12 INSTALLATION TESTS Durability and Strength — The observations during the con- struction of the panels showed that the lath can be securely at- tached to wood supports and that the plaster can be well keyed and bonded to the lath and that the finish becomes very hard and stiff after the plaster has dried out. The observations indi- cate that the lath serves to reinforce the plaster coatings in all directions to such an extent that the finish should be capable of resisting all ordinary stresses and deteriorating influences except excessive moisture and repeated or continued high temperatures. Uniformity — The observations indicate that in the hands of workmen of ordinary ability, this construction can be installed in a uniform and secure manner under the conditions usually found in practice. 13 FIRE ENDURANCE TEST No. 1: This test was made as prescribed in the “Standard Specifica- tions for Fire Tests of Materials and Construction'^ for a non- bearing partition. DESCRIPTION OF TEST PANEL One of the panels built as described for the Installation Test was employed in this test. It consisted of a wood stud frame covered on both sides with the metal lath and gypsum plaster finish under investigation. It was 10 ft. wide and 11 ft. high in the opening in the wall, and approximately 5j4 in. in thick- ness. The face of the panel exposed to the fire was about 7}4 in. back from the face of the brick wall at one edge and about 6^ in. at the other. The panel was 29 days old when tested and had been allowed to season in freely circulating air inside a building at temperatures well above the freezing point. The panel was firm and sound and apparently in a normally dry condition. The finish on each face of the panel consisted of 24-in. sheets of No. 26 U. S. gauge lath of the expanded metal type and the diamond mesh pattern applied in horizontal courses, a scratch coat of extra fibered gypsum plaster, a brown coat of reg- ular fibered gypsum plaster and a finish coat of lime putty tem- pered with gypsum plaster applied as advocated. At the bor- ders of the panels both lath and plaster were turned at right angles and flanged 2 to 6 in. against the masonry forming the boundaries of the opening in the test wall. On the fire side the thickness of the finish, as measured at 24 points, varied from in. to -Jf in., the average thickness being approximately ^ in. On the unexposed side the thickness of the plaster varied from % in. to J4. in., the average thickness being approximately in. The plastered surfaces were hard and without cracks or other visible defects. The surfaces were smooth and true, so far as indicated by visual observation. There were no cracks at the joints between the panel and the enclosing masonry. The wood trim was in close contact with the plastered surfaces and se- curely attached to the spot grounds. The appearance of the panel before the test is shown by Fig- ures 1 and 2. TEST METHOD The standard test equipment described in Appendix V was used in the test. The movable wall carrying the panel was drawn in front of the furnace, the end wall closed, the apparatus for measuring furnace pressures, deflections and temperatures installed and the fire started. The inner face of the panel was exposed to 14 FIRE ENDURANCE TEST No. 1 the standard fire conditions in which the temperature rises rap- idly to approximately 1500 degrees Fahr. during the first 30 minutes, to approximately 1700 degrees Fahr. at the end of one hour and then gradually upward until the end of the test. (See Fig. 6.) The test was continued until the panel failed by the passage of fire through it, after which the fire in the furnace was extinguished and the panel was immediately drawn away from the furnace and sprayed with water until the fire in the burning parts was extinguished. Observations were made throughout the test covering the distribution and general character of the fire, the color of the panel due to heat, and the pressures and temperatures in the furnace. Observations were made during and after the test covering the flame and heat resisting properties of the panel, develop- ments such as are detailed in the following paragraphs and hav- ing a bearing on either of these features being noted and re- corded. ' Flame Resistance — As indicated by the passage of smoke or flame into, through or around the panel due to the development of separations by cracking, spalling, splitting, bulging, or dis- lodgement of the parts, and as indicated by the stability of the panel during and after the test. Heat Resistance— As indicated by any apparent insulating effect on the wood studs afforded by the exposed finish, the con- dition of the materials during and after the test, the tempera- tures at points on the unexposed face of the panel, and the sta- bility of the panel during and after the test. Record was made during the test of the bulging or other * distortion of the face of the panel not exposed to the fire. Thir- teen targets were mounted on the panel as shown in Fig. 2, and readings were taken at 5-min. intervals of their movement by means of a transit telescope. The results of the test were studied to determine the degree of fire protection furnished by the partitions, taking into ac- count their design and construction and the fire exposure to which they are likely to be subjected in ‘the situations and in the classes of buildings for which they are advocated. RESULTS The following is a summarization of the results observed during and after the test, the developments relating to each feature mentioned above and the conclusions drawn therefrom being given under their respective headings. The appearance of the panel before and after the test is shown by Figs. 1 to 5 inclusive. The average indicated tem- 15 WALLS AND PARTITIONS peratures in the furnace and on the unexposed face of the panel are shown by the curves of Fig. 6. Character of Fire — The distribution of the fire was rather un- even for the first 15 minutes, the minimum exposure being in the south upper portion. After 15 minutes, the fire was well dis- tributed. Impinging of jets of flame against the face of the panel was observed at the south portion from 70 minutes to 100 minutes after the start, no impinging occurring at other times. The fire was practically non-luminous for the first hour and slightly luminous during the second and the third hours. The panel showed a trace of color at 5 minutes and was full red at 20 minutes. In 28 minutes the color was bright red in the south central portion and from about 45 minutes until the end of the test, the panel was fairly uniformly a bright red. The pressure in the furnace was slightly above atmospheric throughout the test. The average furnace temperatures were slightly higher than the standard temperatures and are shown by the time-tem- perature curve in Fig. 6. Flame Resistance — On the face of the panel exposed to the fire the wood baseboard, chair rail and picture moulding began to char and burn almost immediately and were practically consumed at 25 min. The wood portions of the spot grounds were consumed as the test progressed, leaving holes through the brown and finish coats down to plaster used to attach the grounds. See Fig. 3. The metal bases of the spot grounds re- mained in position throughout the test and no openings were formed through the finish or splitting or cracking of the plaster was caused by the spot grounds. At 20 min., a small vertical crack was noticeable in the plas- ter on the north side above the chair rail. At 35 min. another small crack developed south of the middle of the panel and below the chair rail. The length and width of these cracks gradually increased as the test progressed, the increases in width being caused by the bulging of the brown and finish coats on each side of the cracks. At 1 hr. and 50 min. a third crack developed south of the middle, and several other cracks occurred later in the test, but these did not open up to any great extent. The first and second cracks at 80 min. appeared about 1 in. and ^-in. wide respect- ively, and at the end of the test 2 in. and 1 in. wide, respectively, at the middle, the first crack extending nearly the full length of the panel. The scratch coat apparently was intact. The fact that very little gas from the burning studs entered the furnace during the test also indicates that the scratch coat remained fairly tight, although the character of the fire after one houi showed the escape of some gas through the finish. Examination 16 FIRE ENDURANCE TEST No. 1 after the test showed the scratch coat in position on the lath and that it was considerably cracked and otherwise injured by local buckling in the lath. At 30 min. the plaster was bulged slightly away from the fire at the middle of the panel. This bulging gradually in- creased in area and extent as the test progressed until at 3 hours it had extended over an area about 4 ft. wide and 6 ft. long and was apparently away from the fire at the middle of the panel. The plaster was apparently completely calcined but did not fall at any point during the test and no openings developed that would permit the passage of flame through the finish. The strength of the plaster was mostly destroyed. The brown and finish coats were insecure and portions fell from position when the panel was drawn from the furnace and sprayed by a ^-in nozzle at the end of the test. The appearance of the panel at 3 hours is shown by Fig. 3. The studs were almost entirely consumed and afforded no support for the finish. The remain- ing fragments of the studs were glowing freely. All of the finish on the fire side of the panel was very insecure and it fell from position about an hour after the panel was withdrawn from the furnace when one of the lower corners was slightly disturbed by a small pinch bar inserted between the brickwork and the flanged edge. The appearance of the panel after the collapse is shown by Fig. 4. On the unexposed face of the panel, steam appeared at 15 min., at some points at the edges, becoming less in volume at 30 min. and practically ceasing at 55 min., when smoke began to appear at some points at the edges. At 65 min. slight smoke passage developed at a crack near the middle of the panel and at other cracks in this locality at 100 min., the finish being con- siderably cracked down through the middle of the panel at this and later periods. Smoke issued at other cracks and increased in volume as the test progressed. At 2 hr. and 50 min. smoke developed at the chair rail and picture moulding and small flames developed near the north and south ends of the chair rail 9 and 10 min. later, respectively, being apparently caused by the transmission of heat rather than the passage of flame through the panel. The panel was removed from the furnace at 3 hr., 134 min., at which time the wood studs had been largely destroyed and were burning briskly. The condition of the un- exposed face of the panel after the test is shown by Fig. 5, the photograph having been taken after the chair rail was almost totally consumed. These observations indicate that when in good condition and exposed to fire that has passed the incident stage and involves freely burning material in the interior of a building, this con- 17 WALLS AND PARTITIONS struction will serve as an effective barrier to the passage of flame into opposite areas for periods in excess of one hour. Under most conditions the finish will serve to prevent such flame passage until the attachments fail and collapse takes place. Fire will be transmitted by conduction to the wood sup- ports and other combustible material in hollow spaces of the construction before the finish fails by the formation of openings. Heat Resistance — The degree of heat insulation afforded by the finish was not clearly apparent from the observations made on the face of the panel exposed to fire, but it was practically certain that fire reached the studs by the heat transmitted through the finish by conduction or through small cracks caused by buckling or expansion. Separations in the outer two plaster coatings occurred at 20 min. and at later stages the openings in these coatings were sufficiently large at two points to permit the heat and flame to reach the scratch coat directly. The plaster coatings possessed sufficient strength and adhesion to remain in position through the entire test, rendering it impossible to observe when the studs took fire. The condition of the fire in the furnace at 1 hr. 15 min. showed that gases from the wood studs were escaping into the furnace, indicating that the wood had been burning for some time previously. At the end of the test the plaster coatings appeared to be thoroughly calcined, and the scratch coat was sufficiently cracked at the separations in the outer plaster coats to permit greater transmission of heat but not passage of flame. On the unexposed face of the panel, steam was noticeable during the first 55 min., after which smoke developed and issued in increasing volume at the edges and at the cracks for the re- mainder of the test. Hair cracks developed in the plaster each side of the middle at 5 min. At 65 min. a long vertical crack north of the middle increased in width and the smoke from this crack became more dense, indicating that the studs were burn- ing. At 1 hr. 40 min., the cracks north of the middle were more marked and the condition of the finish indicated considerable heat on the back side. From this time on the cracks in all parts became more pronounced and indicated severe fire on the inside of the panel. The highest recorded temperature for the unexposed face was 246 deg. Fahrenheit at 2 hr. and 10 min., at which time the thermometers were removed. The maximum’ average tem- perature indicated by the five thermometers on the unexposed side was 230 deg. It is probable that the temperatures at the points where flames first appeared may have been higher at 2 hr. and 10 min. than the temperatures at the points where ther- mometers were mounted. The wooden chair rail ignited at 18 FIRE ENDURANCE TEST No. 1 2 hr. and 59 min. at a point where no cracks in the finish on the unexposed face were observed, indicating that the tempera- ture of ignition of wood had been reached by direct conduction through the plastering on the unexposed face. The observations indicate that when in good condition and exposed to fire that has passed the incident stage and involves freely burning material on the interior of a building, the heat insulating property of the finish is sufficient to prevent the transmission of fire to the wood supports back of it for about 45 min., and that the passage of fire to the opposite area will occur by the transmission of heat through the construction by conduction before openings are formed that will permit the passage of flame. . The bulging or distortion readings taken during the test are shown in the following table for. the 15, 30, 45, 60, 120 and 180 minute periods. The targets were numbered consecutively from 1 to 13 beginning in the upper south corner of the panel. Hence the readings of targets Nos. 1, 2 and 3 show movement, if any, at the top edge of the panel and similarly targets Nos. 11, 12 and 13 are for the bottom edge. Nos. 1, 5 and 11 for the south edge. Nos. 3, 9 and 13 for the north edge. Nos. 2, 4, 7, 10 and 12 for the vertical center line and Nos. 5, 6, 7, 8, and 9 for the horizontal center line. Positive readings indicate movement of targets away from the original plane to the east or from the fire. TABLE OF DEFLECTIONS Target Numbers Time of reading minutes 1 2 3 4 5 6 7 8 9 10 11 12 13 Deflections ; in ( decimals of inches. 15 .0 .05 .0 .125 .0 *.075 .15 .05 .025 .10 *.025 .0 .025 30 .075 .05 .05 .20 .0 *.10 .30 0.15 .050 .20 *.025 .05 :025 45 .075 .025 .10 .30 *.05 *.175 .40 .25 .025 .30 *.05 .05 .025 60 .075 .05 .10 .45 *.10 *.125 .60 3.75 .025 . 450*.05 .05 .0 120 .05 .150 1.60 *.30 *.25 1.85 .85 *.050 1 55 *.15 .05 *.10 180 *.05 .250 ; 6 ‘ 3.35 .0 .0 3.25 1.65 .050 3.35 .0 .10 .05 *denotes deflection toward the fire. The deflections show practically no movements at the edges of the panel during the entire 3-hr. period. The bulging at the vertical and horizontal center lines indicates plainly the lamina- tion crack between the brown and scratch coats which is clearly shown in the photograph, Fig. 5. A similar lamination or sep- aration between plaster and coatings occurred on the face of the panel exposed to the fire as shown in the photograph. Fig. 3. The results of this test show that practically no distortion of the wood frame occurred and that the metal lath with the scratch coat of plaster remained in close contact with the wood studs until these studs were burned away. 19 Figure 1 View before test of exposed face of sample used in Fire Endurance Test No. 1 20 fe 2 «-*-i • S T 3 ^ > . ;'- CJ o «g n 3 (U CO CO O O Ph « <-M G O ccJ sa * 2 « «cm 4 ^ « t; o_ iJ ^ ^ to CO OT 5 o c ^ >- c^o 2 ii ^ ’-M a ccj 0 ) I-< ^ a ^ hjo a ^•o'Ojs ■1(1 ;^:.s _ 'G o ^ 2 o|“ ^ CJ g_C +j a ^ CO to CtJ o c >-< S « «u 2 a HD Ij 0) Si CM o o eg o ca'VXi a C C to c ii CO M Si 5 toiG^ 21 'O u mjz W I S CO 1-4 5‘ nS (Q w a o r-l (X Mh . X O o ^ !3 ■*■« d V u 3 M CM O ° s ^ fee ^ |wS u Ji ^ C rt X'v 2 i 5 o e W^ J-, CW V o c«ii CJ CTJ a» M I ^ rt Q to .S§?“ TO C m 2 « 'S ^ "Si? S's ^ 5 ? ‘-' c ° B S*^ w TO . , c o 29 ■5 .0 I TO O .O 4> H .S 3 ^ -o § a> C 2 X 0) SCO . 0) W ,>s ^ - o ^3, C V X RJ 4-* 4> o S RJ fH • Oc.°|^ 1 ) WJt)«-< o . C qj $> rt o o •'”> ots O go X “ jv -M 1 ) . *-• L4H CT5 ^ o r* b c Ui (Ti ^ *-M > 3'0‘S O 30 Figure 14 View showing maximum charring in 2 by 4-in. studs after exposure to standard fire conditions for 75 min. Note charring at nail holes. 31 WALLS AND PARTITIONS the test. The appearance of the unexposed face of the sample after the hose stream was applied to the opposite face is shown by Fig. 15. The gypsum plaster coating, metal lath and the standing fin- ish on the unexposed face were apparently undamaged by the fire. These observations warrant conclusions as to the property of resisting passage of flame similar to those for the Fire Endur- ance Test No. 1. Heat Resistance — The extent of the insulation afforded by the finish was not apparent from observations it was possible to make from the fire side during the test. 32 FIRE ENDURANCE TEST No. 2 The rise of temperatures as indicated by the thermocouples installed in the hollow spaces between studs and in contact with the back of the exposed face of the sample are shown by Fig. 16. The highest temperature recorded on the back face of the exposed face of the sample was 630 deg. F. at 75 min. and all thermocouples registered over 500 deg. F. for this sur- face at end of the test. The highest temperature recorded on the unexposed face of the sample was 176 deg. F. at 75 min. The maximum and minimum temperatures on the unexposed face of the sample are shown by Fig. 16. Observations indicate that when this finish is in good con- dition and exposed to standard fire conditions for 75 min. and then subjected to hose stream for 1 min., the exposed finish will prevent the active combustion of the wood suports back of it for about 45 min., after which period it will continue to prevent the passage of fire through the finish and into the hol- low spaces in the construction for at least one hour. Upon ap- plication of a hose stream immediately following the fire ex- posure, the fire resisting properties of the exposed finish will be destroyed, although the unexposed face of the partition will retain considerable value as a fire retardant, and the strength of the bearing members will not be materially impaired by the charring in. max.) noted on the edges of the studs next to the exposed finish. Bulging and distortion — No marked deflection was observed on the unexposed face of the sample during the test showing that practically no distortion of the wood frame occurred and that the finish and attachments remained in position through- out the test. The appearance of the unexposed face of the sample after test is shown by Fig. 15. FIRE AND HOSE STREAM TEST; This test was made as prescribed in the Standard “Specifi- cations for Fire Tests of Materials and Construction” for a non- bearing partition or wall. DESCRIPTION OF TEST PANEL The remaining panel built as described in the Installation Test was employed in this test, its construction being practically identical with that of the panel used in the Fire Endurance Test No. 1. The finished panel was 10 ft. wide and 11 ft. high in the wall opening and approximately 5^4 in. in thickness. The face of the panel exposed to the fire was about 7^ in. back from the face of the brick wall at one edge and about in. at the other. The panel was 29 days old when tested and had been allowed to season in freely circulating air inside a build- ing at temperatures well above the freezing point. The panel was firm and sound and apparently in a normally dry condi- tion. On the fire side the thickness of the finish as measured at 24 points varied from 16 to 1 in. outside the studs, the average thickness at the supports being approximately %-in. On the unexposed side the thickness of the finish varied from ^ to 1^-in. outside the studs, the average thickness at the supports being approximately it in. The thickness of the plaster formed by the keys on the back of the lath varied from ^ to ^ in. at the joints between the lath to approximately ^ and ^-in. at other points. The plastered surfaces were hard and without cracks or other visible defects. The surfaces were smooth and true. There were no cracks at the joints between the panel and the enclosing masonry. The wood trim was in close contact with the plastered surfaces and securely attached to the spot grounds. The appearance of the panel before the test is shown by Figs. 17 and_18. FIRE TEST: The standard test equipment described in Appendix V was used in the test. '' METHOD The methods employed and observations made were the same as in the Fire Endurance Test No. 1 except that the ap- paratus for measuring deflections was not installed on the un- exposed side, and that the fire test was discontinued at 45 min. when the panel was subjected to a fire hose stream in accord- ance with the standard procedure for a one hour rating. 34 FIRE AND HOSE STREAM TEST RESULTS OF FIRE TEST TEe following is a summarization of the results observed during and after the fire test, the developments relating to each feature and the conclusions drawn therefrom being given under their respective headings. The appearance of the panel before and after the test is shown by Figs. 17 to 20 inclusive. The average temperatures in the furnace and on the unexposed face of the panel are shown by the curves of Fig. 21. Character of Fire — The distribution of the fire was uneven for the first 10 min., the maximum exposure being in the north half. The distribution was corrected slowly and was fairly even at 20 min. and until the end of the test period. The flames did not impinge on the face of the panel to any considerable extent. During the first 10 min. the fire was practically non- luminous; during the later portions of the test it was luminous. The panel showed some color at 10 min. and was uniformly fair- ly red at 20 min. The pressure in the furnace was slightly above atmospheric throughout the test. The average furnace tempera- tures were slightly higher than the standard temperatures and are shown by the time-temperature curve in Fig. 21. Flame Resistance — On the face of the panel exposed to fire the wood trim began to char and burn almost immediately and was practically consumed at 25 min. The wood portions of the spot grounds were consumed later, leaving holes through the brown and finish coats down to the plaster used to attach the grounds. The metal bases of the spot grounds remained in position throughout the test, and no openings through the plaster coating nor splitting or cracking of the plaster was caused by the spot grounds. At 13 and 18 min. small cracks developed in the north middle portion of the panel, and at 15 min. two diagonal cracks occurred in the same locality, but these cracks did not open up to any great extent. At 18 min. a vertical and diagonal crack occurred on the north side near the middle and at 22 min. one of these cracks was about 6 in. long and j4-in. wide, but it was impossible to observe whether or not the scratch coat was involved or if the separation had extended through the plaster coating. The fact that the fire did not show evidence of any appre- ciable escape of gas from the wood in the panel during the test, nor any other evidence that 'the studs had been ignited, seems to show that no openings were formed that would permit the passage of flame through the plaster coating. 35 WALLS AND PARTITIONS At 13 min. a marked bulge was noticeable at the middle portion of the panel. This increased in area and extended some- what as the test progressed, but the plaster did not fall and it was impossible to observe whether the entire plaster coat- ing was involved or only the brown and finish coats of plaster. The furnace fire was extinguished, the panel withdrawn from the furnace at 45 min. and the standard fire hose stream applied about Yz min. later. Observation during this test indicated that the scratch coat was intact and that no openings had been formed through the plaster coating that would permit the passage of flame. On the unexposed face of the panel steam issued at the up- per edge at 6 min. and smoke at 8 min. At 16 min. steam is- sued at the joint between the panel and the brickwork on the north edge and at 25 min. at the south edge, the smoke being still confined to the top edge of the panel. The volume of steam and smoke was limited at all times during the test and did not indicate active fire within the panel. The wood trim was not affected. The appearance of the unexposed face of the panel after the Fire and Hose Stream Test is shown by Fig. 20. These observations warrant conclusions as to flame retard- ant properties agreeing with those reached for the Fire En- durance Test No. 1. Heat Resistance — The degree of heat insulation afforded by the construction was not clearly apparent from the observa- tions on the exposed face of the panel during the test. Body cracks were noted early in the test and although these may not have extended clear through the plaster coating, they undoubt- edly materially reduced its insulating properties. The plaster coats retained sufficient strength to remain in place throughout the test and there was not positive evidence at the end of the test that active fire had been communicated to the studs. Ex- amination after the Hose Stream Test showed that the edges of some of the studs were charred in places to a depth of about but that the sides of the studs were not affected by fire. This and the condition of the charred portions seem to show that no flame or very active fire had taken place, al- though it was evident that at the charred spots the wood was very close to its ignition point. The highest temperature recorded for the unexposed face of the panel was 174 deg. Fahrenheit at the end of the test. The maximum average temperature readings of the five thermome- ters on the unexposed face was 164 deg. The average tem- peratures on unexposed face of panel are shown by Fig. 21. 36 FIRE AND HOSE STREAM TEST Observations indicate that when in good condition and ex- posed to standard fire conditions, the heat insulating property of this construction is such as to delay the ignition of its wood supports for about 45 min. APPLICATION OF HOSE STREAM The standard test equipment described in Appendix V was used in this test. METHOD At the end of the fire test, which lasted 45 min., the panel was immediately drawn away from the furnace and a 1^-in. fire hose stream was applied from a distance of 20 ft. for min. The stream was directed first at the center of the panel, and then at all parts of the exposed face, changes in the direc- tion of the stream being made slowly. The pressure at the base of the nozzle was 30 pounds per sq. in. throughout the period. Observations were made during and after the application of the stream covering the effect of' the impact and pressure and the rapid cooling on the flame retarding properties of the construction as indicated by openings due to contraction, breakage, dislodgements, or separations; and covering the ef- fect of the stream on the heat insulating properties of the panel, as indicated by change in the condition of the material or re- duction in the thickness of the plaster coating by erosion or dislodgement. The results of the test were studied to determine the gen- eral effect of the application of hose streams on the fire pro- tection furnished by the construction. RESULTS OF HOSE STREAM TEST The following results were observed during the test and the examinations after test, the developments relating to each fea- ture and the conclusions drawn therefrom being given under their respective headings. The appearance of the panel after the test is shown by Figs. 19 and 20. Fire Resistance — On the face of the panel exposed to the fire and to the hose stream the flame retarding and heat in- sulating properties of the plaster coating were almost imme- diately destroyed when the stream was applied. Most of the plaster coating was dislodged at the end of the test but the lath remained securely in position. The outer plaster coat- ings were badly calcined by the heat and did not possess suf- ficient strength to resist the impact and eroding effect of the stream. They were thrown off in fairly large pieces under the action of the water, the dislodgements immediately following 37 WALLS AND PARTITIONS the changes in direction of the stream. The scratch coat also was badly calcined, except at the edges and in the lower north corner, and was mostly dislodged by the impact and eroding action of the stream, the keys being broken from the lath. These results show that the fire resistance of a single finish is destroyed b}^ hose streams after exposure to a standard fire for about 45 min. and indicate that this would be the case with an initial fire exposure of much shorter duration. This is due to the fact that the strength of the gypsum plaster coat- ings is destroyed by calcination. On the unexposed face of the panel the flame retarding and heat insulating properties of the construction were practically unimpaired. The metal lath on the exposed face remained in position and prevented material erosion or other mechanical damage from the hose stream to the plaster coating on the unex- posed side. These results show that a wood stud partition or wall hav- ing the described metal lath and gypsum plaster finish on two sides retains a very considerable value as a retardant to pass- age of heat and flame when exposed on one face to the stand- ard fire conditions for 45 min. and to the impact and erosion of a standard hose stream and indicate that this would be the case for initial fire exposures prior to application of hose stream of considerably greater duration. 39 Figure 17 Figure 18 View of exposed face of panel used in Fire View of unexposed face of panel used in Fire and Hose Stream Test before test. and Hose Stream Test before test, showing location of thermometers mounted on face of sample. 4> C -M J-i U, C CO v O 4> ft •S-d -• — «y3 .S ^ > O c ^o^coH “ l-S EiS “ ^-S S-s a, 1) ft '2 ^ « (uij ^ o Ij ™ l“sl « rt L. ^ S c «3 Q .y u -M ffi S‘d ^ Hh CO i > £-« S CO CO 40 SUPPLEMENTAL FIRE AND HOSE STREAM TEST: This test was made to develop the extent of damage to the finish of the standard hose stream applied after fire ex- posures of shorter duration than in the Standard Fire En- durance Tests and the Standard Fire and Hose Stream Test. DESCRIPTION OF SAMPLES The three special samples employed in this test were finished on the side exposed to the fire with a metal lath and gypsum plaster on wood frame construction similar to that of the samples which were subjected to the Standard Fire Endurance Test No. 1 and to the Fire Hose Stream Test, but were of reduced dimensions so that when mounted for test the area exposed to the fire and subsequently to the hose stream was in each case 20 in. wide by 12 in. high. 41 WALLS AND PARTITIONS METHOD Each sample was separately exposed to fire, and immediately thereafter was subjected to the impact eroding and cooling ef- fects of a hose stream. The tests were made in the Underwriters’ Laboratories’ Furnace No. 4, which for the purpose of this test was pro- vided with a rectangular opening 20 in. wide and 12 in. high in the brick panel forming the front wall of the furnace. In each test the sample was mounted on the outer face of the 8-in. front wall, so as to be exposed to the fire through the rectangular opening. Exposure to fire continued for 30 min. in Test A, for 15 min. in Test B, and for 15 min. in Test C. The temperatures within the furnace were indicated by means of a Hoskins thermocouple mounted opposite the center of the test sample and 8 in. from the exposed face. After exposure to fire for the assigned period, each sample was removed from the furnace and subjected to the action of a hose stream from a 1^-in. smooth nozzle, 20 ft. from the sample, the pressure at the base of the nozzle being 30 pounds per square inch. In tests A and B the hose stream was ap- plied for two periods of 2 seconds each, or a total of 4 seconds. In Test C the application of the stream was for five periods of 2 seconds each, or a total of 10 seconds. Inasmuch as the exposed area of each sample was 1% sq. ft., as compared with 110 sq. ft in the sample used in the Standard Hose Stream Test, a duration of 2^ seconds in each Supplementary Hose Stream Test would be equivalent to the 2^ min. of the standard test. The usual observations of' the condition of each sample were made during the exposure to fire. Detailed observations were made after the application of the hose stream in order to de- termine whether the sample, after its exposure to fire, was se- riously impaired by the impact and erosion of the stream. RESULTS The temperatures within the furnace were substantially ac- cording to the Standard Time-Temperature Curve, and are stated in the following tabulation. The unusually high initial temperatures in Tests B and C were due to the fact that the furnace was not permitted to cool to room temperature after Tests A and B. 42 SUPPLEMENTARY FIRE AND HOSE STREAM TESTS Time in Temperature— -Degs. Fa Minutes A B C 0 75 430 125 5 1060 975 975 10 1200 1260 1300 15 1415 1400 1425 20 1475 25 1500 30 1560 There were no significant developments during the exposure to fire. Condition of Samples After Test — Sample A, exposed to fire for 30 min., and to the hose stream for 4 seconds, suffered considerable damage during the first two seconds of applica- tion of the stream and after 4 seconds its finish coat was prac- tically all washed away, about one-half the brown coat was gone, and the metal lath was exposed at three places as shown in Fig. 22. All plaster which was still in place was soft and water soaked. After exposure tO' fire for 15 min., and to the hose stream for 4 seconds, the finish coat of sample B was washed from about three-fourths the area. The remaining portion of the finish coat could be penetrated easily with the point of a knife blade, but calcination was not complete. The brown coat was considerably eroded in those portions where it was uncovered by the removal of the finish coat. It was soft in the upper portion, but firm in the lower half of sample. At no point was the scratch coat or the metal lath exposed. Later when the brown coat was removed, the scratch coat was found to be soft and watersoaked in those portions of the sample where the brown coat was soft. The appearance of the sample after test is shov/n in Fig. 23. After being exposed to fire for 15 min. and to the hose stream for 10 seconds, practically all the finish coat of Sample C and about 80% of the brown coat were washed away. The scratch coat was carried away over a considerable area, as in- dicated in Fig. 24. All plaster remaining in place was water- soaked and very soft. These results demonstrate that a construction comprising gypsum plaster on metal lath without back-plaster or other finish on the keys, subjected to standard fire exposure for a pe- riod exceeding 30 min., loses strength through calcination suf- ficiently to permit the impact and eroding effect of standard hose streams to remove the plaster coating so that water may enter freely into the concealed spaces behind the lath. 43 Figure 22 View of sample A used in supplementary Fire and Hose Stream Test after exposure to standard fire conditions for 30 min., when a l^in. hose stream, 30 lbs. per sq. in., was applied for two periods of 2 seconds each, a total of 4 seconds. Figure 23 View of sample B used in supplementary Fire and Hose Stream Test after sample was exposed to standard fire conditions for 15 min., then a 154-in. hose stream, 30 lbs. per sq. in., was applied for two periods of 2 seconds each or a total of 4 seconds. 44 Figure 24 View of sample C used in supplementary Fire and Hose Stream Test, after sample was exposed to standard fire conditions for 15 min., then a 1^-in. hose stream, 30 lbs. per sq. in., was applied for five periods of 2 seconds each or a total of 10 seconds. 45 SECTION II Retardant No. 1355 INTERIOR FLOOR AND CEILING CONSTRUCTION AS A FIRE RETARDANT Consisting of Metal Lath and G 5 rpsum Plaster on Wood Joists With Rough Wood and Finished Flooring The influence of floor and ceiling construction on the spread of fire within buildings is of importance. Fire resistive proper- ties in floor construction provide a barrier to the upward spread of fire and preserve the structural integrity of a building under fire conditions. Such constructions retain these properties under service conditions incidental to the ordinary use of the buildings. These requirements necessarily involve all the parts that are assembled to finish or effect the subdivision of the building into stories, including the vertical communications. This report deals with the solid or unbroken portion of the floor areas of a representative wood joisted floor finished on the underside with metal lath and gypsum plaster. It de- velops mainly the fire retardant properties secured by the use of this construction. DESCRIPTION: GENERAL CHARACTER The floor construction forming the subject of this report is of the wood joist, expanded metal lath and gypsum plaster pattern. It consists of the wood joist, its bridging, the rough wood floor, the insulating material, the furring strips, the finished top floor, the metal lath, its fastenings, the gypsum plaster finish. The finished floors vary in thickness, depending on the spans and loads they are designed to carry and are de- signed to be used for buildings of any area, with proper lay- out of girders and other supports. The wood joists, spaced 12 or 16 in. on centers, usually 16 in., are supported at each end, in some cases at intermediate joints, by the structural members of the building upon which they rest. The bridging is between the joist at intervals be- tween the supports. The rough flooring is nailed directly to the top of the joist and is entirely covered by the insulating ma- terial, which is in turn held in place by the furring strips which are located over the joists and are nailed to the rough floor- 46 DESCRIPTION ing. The tongue and grooved top flooring covers the entire upper surface of the floor and is nailed to the furring strips. The metal lath is attached directly to the bottom edges of the joists by nails or staples driven into the joist. The gypsum plaster finish is applied in three coats to the metal lath and is ^-in. in thickness. USE This construction is regularly used in buildings of fr:ir.ic or ordinary construction, wherever standard fire resisfi\ c c struction is not required. DESCRIPTION OF PARTS Complete description of parts used in this construction is given in this report under the heading “Examination and Test Record.’' INSTALLATION Complete specifications for the preparation and application of metal lath and gypsum plaster construction on wood sup- ports is given in Appendix III. CLAIMS MADE BY THE SUBMITTORS Claims for this construction as set forth by the Submittors are given in Appendix IV. OBJECT OF INVESTIGATION The object of the investigation was to ascertain the value from the fire protection viewpoint of the construction described and to determine its classification under the “Specification for Standard Fire Tests of Materials and Construction,” as given in Appendix VII. PLAN OF INVESTIGATION The general features of the investigation covered the sub- jects of Practicability, Durability, Strength and Uniformity, as well as of resistance to Fire and to Fire Hose Streams and Load Tests. In considering these subjects the features of Handling and Shipping, Preparation for and actual Installation, Mainten- 47 FLOORS AND CEILINGS ance, Wear and Tear, Moisture, Heat, Flame Resistance and Heat Resistance were severally studied. Data covering these features and properties were obtained during the preparation of specimens for tests, during the actual conduct of tests and in studies of the specimens and their units after tests. THE FOLLOWING TESTS WERE MADE Installation Test Standard Fire Endurance Test. Standard Fire and Hose Stream Test. Excess Load Test. The procedures employed in these tests and the performance of the specimens in the tests are reported in the following sec- tion entitled “Examination and Test Record.’' EXAMINATION AND TEST RECORD A record of the tests and examinations made is given in this section of the report. 48 INSTALLATION TESTS: DESCRIPTION OF SAMPLES The material required for the construction of the floor and ceiling sample consisted of the following units which were fur- nished by the submittors. 4 Joists, 2 by 12 in. by 18 ft. No. 1 rough Southern Yel- low Pine. 17 Joists, 2 by 10 in. by 14 ft. No. 1, Southern Yellow Pine. 2 Boards, 1 by 10 in. by 18 ft. No. 1, Southern Yellow Pine. 60 1^ by 3 in., No. 2 Yellow Pine bridging. 48 Pieces, 1 by 6 in., No. 2 Yellow Pine rough flooring. 26 Pieces 2 by 2 Yellow Pine furring strips. 93 Pieces 1 by 4 in., B or Better dressed, matched Yellow Pine flooring. 1 Bundle of Cabot’s Quilt. 2 Bundles No. 24 U. S. gauge expanded metal lath 24 in. wide and 96 in. long. 13 Bags of prepared wood fibered gypsum plaster. 2 Bags of hydrated lime. 1 Bushel of hair. 5 lb. No. 12 annealed wire. 12 lb. No. 18 annealed wire. 4 lb. 3^-in. 16-penny wire nails. 5 lb. 2j4-in. 8-penny wire nails. 6 lb. 2j4-in. 8-penny wire nails. 6 lb. 2-in. 6-penny wire nails. METHODS The test panels were installed so as to All the opening in the top of one of the standard floor test furnaces described in Appendix VI. The test panels were installed as nearly as possible in ac- cordance with the methods advocated by the submittors. The wood supports, joists and flooring were installed by experienced carpenters in the employ of a local contractor, under the di- rection of a representative of the National Lumber Manufac- turers’ Association. The metal lath and plastering was in- stalled by experienced lathers and plasterers in the employ of a local contractor, under the direction of a representative of the Associated Metal Lath Manufacturers. All the work was done under the observation of the Laboratories’ engineers. The methods of installation were observed during and after the installation of the test panels and studied in connection with the drawings and specifications submitted. 49 FLOORS AND CEILINGS RESULTS The following results were observed during and after the installation of the samples. The appearance of the test sample during and after in- stallation is shown by Figs. 25 to 32 inclusive. Preparation of Materials — The lumber was fairly straight and true and required no special preparation for installation except to cut to the desired length. The sheets of metal lath required no special preparation before application except cut- ting to the desired length with ordinary snips. The plastering materials were delivered to the Laboratories and stored in a clean, dry place until used. Observations indicate that the amount of preparation necessary depends on the condition of the materials when they are received at the job and the pro- visions made for storing the same until they are ready for in- stallation. Installation of Woodwork — Details are shown by Figs. 25 to 29 inclusive. Four 2 by 12-in. rough joist were cut 17 ft. 11 in. long. Two pieces were nailed securely together by 3-in. nails and in- stalled along each side of the furnace restraining frame resting on four metal steel stirrups on each side. The 2 by 10 dressed joists were cut 13 ft. 6 in. in length and installed at 16-in. cen- ters. 1^ by 3-in. bridging pieces were cut and installed be- tween joists. The ends of the channels between the joists were closed by nailing a 1 by 10-in. dressed board across the ends of the joists. The 1 by 6-in. rough flooring was laid contiguously and transverse to the joists to which it was secured by 2^-in. wire nails, two nails to each joist. The joints between the ends of the boards were broken. The quilt was applied in longitudinal courses lapping at the adjacent edges 2^ to 5 in., averaging about 3 in. The 2 by 2-in. furring strips were attached over the quilt around the edges of the panel and along the top of each joist and was se- curely attached through the quilt and rough flooring joist by 3F2-in. nails driven into each joist. The 1 by 4-in. dressed and matched flooring was laid over the furring strips; 2^-in. cas- ing nails were used, one nail to each furring strip. Application of Metal Lath — Details are shown by Figs. 26 and 30. The metal lath was applied to the under side of the joists in longitudinal courses, beginning along the junction between the wall and ceiling. The outer sheets were bent down! so that they lapped the wall joint about 7 in. Each successive course was laid so that the edges and ends overlapped from 1 50 INSTALLATION TESTS to 2 in., averaging about 1)4 in. The transverse joints between sheets were broken. The lath was attached to the joists by 2-in. common wire nails, spaced from 5 to 7 in., averaging about 6 in. The nails were driven into the joist about in. and then bent across the meshes of the lath. The lath was attached along the gyp- sum side walls of the furnace combustion chamber by 2)4-in. common wire nails, spaced about 7)4-in. centers and about 3 in. below the junction of the wall and ceiling. The overlapped edges were tied with No. 18 annealed wire midway between joists. Preparation and Application of Plaster — Details are shown by Figs. 26 and 31. The plaster for the scratch coat was prepared in an ordinary mixing box ; a layer of about 4 cubic feet of the prepared wood fibered gypsum plaster was placed in the box and about lb. of hair. The mixture was thoroughly mixed dry; then water was added to the desired consistency. The mixture was then turned several times. The plaster for the second coat was similar to the first coat except that the hair was omitted in this coat. The finishing coat was composed of hydrated lime and prepared gypsum plaster with the fiber removed and was mixed in about the proportion of one to one. Nails were attached to the under side of the joist to serve as a gauge for the plaster. These nails were removed before the finish coat was troweled to a uniform surface. The first coat of plaster was applied lightly but with suffi- cient pressure to force it well through the mesh, to imbed the metal lath and form full keys. Sufficient plaster was next ap- plied to cover thoroughly the lath and extend from to ys-in. outside the lath. After this coat had set for a few minutes its surface was thoroughly scratched in both directions with the edge of a piece of the metal lath. After the scratch coat had dried for about 18 hours, the brown coat was applied. Sufficient plaster was spread on to bring the coating out nearly flush with the nails and the sur- face was then made straight and true with a rod and darby, but was left rough under the tools to furnish a bond for the finish coat. After the brown coat had dried for about two days the finish coat was applied. The surface of the brown coat was first sprinkled with water and a thin coat of the plaster was then thoroughly troweled on, applying enough plaster to cover 51 FLOORS AND CEILINGS the brown coat completely. Enough additional plaster was then applied to make the surface straight and true. The surface was then gone over again with the material as thin as it could be handled and all imperfections worked out and the coating troweled and brushed to a smooth, uniform surface. The observations made by the engineers showed that if or- dinary facilities are provided these plasters can be properly handled and mixed by workmen reasonably familiar with this class of work. The mixing box must be tight and of ample size for the batches used and the workmen must understand the imporfance of obtaining the proper proportions and of prompt completion of the batch mixes, of clean tools, and of avoiding the use of mixed plaster that has commenced to set. Maintenance — The observations during the construction of the floor indicate that the materials are of such a form and so arranged that the injured portions can be removed, replaced and repaired, and that the repaired portions will be practically equivalent to new work. Durability and Strength — Observations during the installa- tion of the floor and a study of the design and construction in- dicate that these floors are capable of withstanding all ordi- nary influences for long periods, except moisture and tempera- tures above 200 deg. The secure manner in which the various materials are assembled and attached, and the known prop- erties of the materials indicate that these floors are capable of withstanding all ordinary stresses to which they are likely to be subjected in the classes of building for which they are advo- cated. Uniformity — The observations during the installation indi- cate that the materials are made with a fair degree of uniform- ity and that they can be installed in a satisfactory manner in the field by workmen having a reasonable amount of expe- rience with material of this character. 52 in lU QC 0 < a. § < in a: u K 5 c Id Q Z D 53 underwriters laboratories R .1505 Figure 27 View of joist assembly and cross bridging before flooring and metal lath and gypsum plaster ceiling were installed. View looking west into top of furnace. Figure 28 View showing the top flooring installed, the layout of targets for measuring deflections and layout of tubes for inserting thermocouples into joist bay spaces. Brick load not yet applied. View looking west at top of furnace. 54 Figure 29 View of joist bridging and underside of rough flooring taken before installation of the metal lath, looking west and upwards into com- bustion chamber space before chamber side walls were built in. Figure 30 View showing metal lath installed and plaster not yet applied. View looking west and upward into furnace chamber, the west wall of which is built in except for the temporary opening at center. Ob- serve lapping of lath down side wall. 55 Figure 31 View showing plaster finish installed; also showing thermocouples 3 and 4 in place. View looking west upward and into combustion chamber showing observation windows mounted in west wall. Figure 32 View of Floor and Ceiling Construction before and after test, with rated load of 50 lbs. per sq. ft. in place, showing deflection targets and thermocouples wired to junction box. View looking west across top of furnace. 56 FIRE ENDURANCE TEST: DESCRIPTION OF SAMPLE The test was made in accordance with the provisions of the Standard Specifications for Fire Tests of Building Materials and Construction. The test specimen was installed in the fur- nace as previously described and as shown by the illustrations Figs. 25 to 31 inclusive. The design of the furnace is described in Appendix VI of this report. Object of Test — The object of the test was to determine the condition of the construction at the expiration of the test pe- riod required for a one-hour classification. Accordingly the test was continued for one hour and 15 min., the specified ex- tended period for a 1-hr. classification (80% of 75 min. equals 60 min., 1 hr.). METHOD OF TEST The test specimen installed as previously described was allowed to remain in position for 30 days after application of the gypsum plaster ceiling finish. During this period the fur- nace was housed with wood sheathing protecting the construc- tion from severe weather variations. Salamanders placed at outside corners of the furnace and within the frame enclosure assisted in preventing undue absorption of atmospheric moist- ure. Five days previous to the fire test the floor construction was loaded with fire brick placed to provide a uniform loading of 50 lbs. per sq. ft. This loading corresponds to the recog- nized loading for joisted floor constructions like the specimen considered in this report. Deflections were measured from level readings of the targets mounted on the specimen. Read- ings taken before and after this load was applied and during and at the conclusion of the test. The Fire Endurance Test was made on the afternoon of Thursday, April 6, 1922. Representatives of the submittors at- tended. The temperatures within the furnace were regulated by means of gas and air control valves and were maintained in close agreement with the Standard Time Temperature Control Curve. Observations were made during the test of the distribution and general character of the fire, the color of the ceiling finish due to heat and of the combustion chamher pressures. Observations were made throughout the test period cover- ing the flame retarding properties of the construction as indi- cated by appearance of smoke and flame through the plaster finish, the formation of cracks or larger openings permitting the passage of flame into the hollow construction, the passage of smoke and flame through the sample and the extent of flame passage and of combustion at the conclusion of the test. 57 FLOORS AND CEILINGS Observations were made during and after the test covering the heat insulating properties of the construction by thermo- couples placed within the joist spaces and adjustable in a vertical plane, and by the condition of the materials after test. Observations were also made during and after the test cov- ering the effect of the fire exposure provided by the test condi- tions on the stability of the construction as indicated by de- velopment of cracks, bulging, spalling, calcination or other evidence of insecurity and by the condition of the structural parts after the test. At the conclusion of the 75-min. period the furnace fire was shut off and the joist bay spaces were sprayed with water, thereby extinguishing incipient fire, if any, within the hollow construction. This permitted subsequent study of the fire dam- age to the combustible units of the assembly and determination of residual structural strength. Results of Fire Endurance Test, Figs. 32 to 40 inclusive, show condition of the assembly and its units following the test. RESULTS The following observations were made during the test and after : Character of Fire — The fire was well distributed throughout the combustion chamber during the entire 75 min. period. Strong jets of flame impinged directly upon the ceiling sur- face from each of the burners throughout the period. The com- bustion chamber was completely filled with a thin luminous flame for practically the entire period. The temperatures read on the couples within the combustion chamber were as shown in Fig. 41. The curves show that the average temperatures were slightly above but in close agreement with the standard curve for the entire test period. Flame Resistance — The ceiling surface was under observa- tion during the entire test period without occurrences worthy of note, except a north and south fire crack in the approximate center which was noted before test and which became slightly enlarged at 50 min., and a series of waves in the plaster sur- face during the last 10 min. of the period. No openings were formed in the ceiling finish which per- mitted the passage of flame into the hollow construction. On the upper face of the test panel steam was noted at 40 min., and continued to issue in small volume during the remainder of the test. At 50 min. a slight odor of smoke mixed with steam was detected, but this odor was not very marked at any time during the remainder of the test. 58 FIRE ENDURANCE TEST The water dislodged the greater part of the brown and fin- ished coat after test, also the weight of the water pulled the lath slightly from position on its supports. The condition of the metal lath and gypsum plaster finish after test is shown b}^ Figs. 36 to 39 inclusive. These observations indicate that when in good condition and exposed to fire that has passed the incipient stage and in- volves freely burning material in the interior of a building, wood joist floor construction finished on the under side with metal lath and three-coat ^-in. fibered gypsum plaster, will serve as an effective barrier to passage of flame through the joist assembly for considerably more than one hour. Under most conditions the construction will serve to prevent such flame passage until the attachments fail and collapse takes place. - Fire will be transmitted by conduction to the wood supports and other combustible material in the hollow spaces of the construction before the finish fails by the formation of openings. Heat Resistance — The observations on the top of the floor indicated that the transmission of heat through the test sample was very slight throughout the test. The general appearance of the unexposed face at 1 hr. 15 min. was practrcally as before test. The highest temperature reading of the' thermometer mounted on the upper face of the top flooring whs 100 deg. F. at 73 min. Observations of the lower face of the sample; failed to de- velop the exact points at which transmission of heat through the plaster ceiling most affected the wood supports. The tem- peratures as taken between the joist bays about two inches away from the back face of the exposed finish are shown by Fig. 41. The locations of the thermocouples are shown by Fig. 32, numbering from north edge of panel. Couples marked No. 5 and 8 which were installed in the middle of joist way No. 6 .and 9, respectively, from the north edge of panel, showed the highest temperatures.’ Observations indicate that when this construction is in good condition and exposed to fire that has passed the incipient stage and involves freely burning material in the interior of build- ings, the heat. insulating property of the finish is sufficient to prevent the transmission of fire to the wood supports back of it for about 45 min., and that the passage of fire into or through the assembly will occur by transmission of heat through the finish by conduction before openings are formed in the finish that will permit the passage of flame. 59 Figure 331 View o£ Floor and Ceiling Construction after Fire Endurance Test, looking north at top of furnace. Brick load and top flooring re- moved, showing condition of 2 by 2 in. furring strip and of the in- sulation. Rough floor in the center strip was removed after test to permit inspection of joist and joist bay spaces. Figure 34 View of Floor and Ceiling Construction after Fire Endurance Test, looking south at top of furnace. Brick load and top flooring re- rempval. Observe that darkened portion at west is from shadow of furnace roof and not from effects of Fire Test. 60 Figure 35 View of Floor and Ceiling Construction after Fire Endurance Test, looking south into top of furnace. A close-up of the under-sides of the rough flooring, showing smoke and heat stains. Boards in same relative position as during test. Figure 36 View of Floor and Ceiling Construction after Fire Endurance Test, looking west into top of furnace, showing brick load and flooring removed and the general condition of the joist and bridging. 61 FLOORS AND CEILINGS Deflection — The deflection at the middle of the panel before test was 0.20 in. in 120 hrs. after the uniformly distributed load of 50 lbs. per sq. ft. was applied, or about one-half of the com- puted deflection. During the Fire Endurance Test this deflec- tion increased to a total of 1.08 in. at 75 min., when the furnace fire was extinguished. The total deflection after the water was applied was 1.48 in., which decreased to 1.18 in. five days after the brick load was removed. FIRE AND HOSE STREAM TEST: A Fire and Hose Stream Test was not made in. the case of the construction under consideration in view of the Fire and Hose Stream Tests made on metal lath and gypsum plaster mounted on vertical wood supports, which are fully described in Section I of this report. Also in addition to these tests a Stand- ard Fire and Hose Stream Test was previously made on a wood joist floor construction similar to that under consideration, except that portland cement plaster was used instead of gyp- sum plaster for the ceiling finish. These tests are fully de- scribed in Appendix I. Figure 37 Flooring and Ceiling Construction after Fire Endurance Test. Close- up view looking into top of furnace (southeast quarter); showing condition of joist, bridging and plaster finish after test in the area where the damage to these members was most marked. 62 Figure 38 View of Floor and Ceiling Construction subjected to 75-min. exposure to standard Fire Endurance Test. This photograph shows arrange- ment of parts comprising the construction. f)3 Figure 39 View of Floor and Ceiling Construction after Fire Endurance Test, looking into furnace chamber. The plaster fell from position after the furnace fire was shut off and water had been sprayed into joist spaces above the metal lath and plaster ceiling assembly. EXCESS LOAD TEST: The sample employed for this test was of a construction like the sample covered by this report, except that ^-in. three-coat Portland cement plaster ceiling finish was used instead of gyp- sum plaster. METHOD The sample was loaded with common brick, 50 lbs. per sq. ft., then subjected to standard fire conditions for 45 min., and immediately subjected to a Standard Hose Stream Test con- sisting of 1^-in. stream of water, 30 lbs. per sq. in., for 5 min., following which it was allowed to cool and then subjected to two and one-half times the safe rated load, or 125 lbs. per sq. ft., as specified in the Standard Specifications for Fire Tests of Materials and Construction described in Appendix VII. An account of this test and the results are given in Appendix I, Fire and Hose Stream Test and Excess Load Test. 64 Figure 40 Floor and Ceiling Construction after 75-min. exposure to Standard Fire En- durance Test. Section of joist No. 4 (Fig. 37) showing maximum charring at lower edge of joist. Original dimensions It^s by 954 in. (dressed), nom- inally 2 by 10 in. 66 SECTION III SERVICE RECORD The fairly general use of metal lath as a base for plaster coatings extends over a period in excess of a quarter century, during which period many instances of satisfactory perform- ance under various fire conditions have occurred. A detailed statement of record in service seems unnecessary in this report in view of the general familiarity with its uses and perform- ance. SUPERVISION OF PRODUCT BY UNDERWRITERS^ LABORATORIES: It is contemplated that standards for metal lath correspond- ing to the material used in the construction of the test samples described herein shall be drawn up and applied to the products of the several members of the submitting association. Inspection at factories and labeling of standard metal lath permitting its identification wherever used is under considera- tion. The Submittors will enter into a contract with the Lab- oratories for the Reexamination Service permitting systematic observance of the service record of the construction covered by this report. CONCLUSIONS Metal lath on wood supports serving as a base for gypsum plaster on the inside of buildings is sometimes employed as a single finish on ceilings, as in attics and side walls. When em- ployed for corridor and room partitions, for walls and for en- closures to vertical openings the usual practice is to finish each side of the partition, wall or enclosure. General considerations of practicability, durability, strength and uniformity may be discussed in common for single or double finish and are so treated in the following. From the fire retarding viewpoint the test results emphasize a material variation in performance. Accordingly individual discussion and rating of single and double finish construction involving metal lath and gypsum plaster and of the wood joisted floor and ceiling construction is essential. PRACTICABILITY: Metal lath, the lumber and the other materials employed can be handled for shipment and at buildings without fear of break- age or other material injury, and can be installed, renewed and repaired in the manner advocated without difficulty by ordinary 67 CONCLUSIONS workmen, and without serious impairment of structural fea- tures or of the fire retarding properties of the final assembly. The gypsum plaster and other ingredients for the plaster coating require no special care or treatment in handling, ship- ping or installation beyond that regularly given to these ma- terials generally. The mixing and application can readily be performed in the manner advocated, which differs in no es- sential respect from that regularly employed. The conclusions are indicated by the results of observations made before and during the Installation Tests and from com- mon knowledge of field practice and from the service record. DURABILITY: • Excessive free moisture and frequent or continued exposure to temperatures in excess of 200 deg. F. cause deterioration and calcination of gypsum plaster coatings. A construction employ- ing this plaster should not be advocated for such conditions. In other respects the gypsum plaster coating, like the lumber and the metal lath, is capable of resisting all ordinary deterior- ating influences for long periods. The service record of this construction, the known proper- ties of the materials comprising it and field experience confirm such a conclusion as to durability drawn from observations made during the Installation and subsequent tests described in this report. STRENGTH: The wood stud and wood joist construction under consid- eration, including the fabricated metal reinforcement which provides a positive key for the plaster, possesses ample strength for the uses considered and will withstand without failure or ma- terial damage all ordinary stresses or loads to which it may be subjected under the service conditions likely to be met with in the class of buildings for which they are advocated. The heat insulating value of the gypsum plaster preserves the combust- ible load bearing units from ignition for fairly long periods under standard fire exposure conditions. This conclusion is based upon the known properties of ma- terials and upon field observations, the service record and the fire endurance and the load tests. UNIFORMITY: No unusual care or precision is required to ensure practi- cal uniformity of assembly, security or performance in the con- structions. 68 FIRE RETARDANT PROPERTIES The metal lath, the lumber and other materials employed in the constructions are capable of close control as to quality of material, weight and other dimensions. The installation and assembly of materials and the plaster coating is capable ot control to a sufficient degree and proper measures of control are commonly employed in the plastering and other building trades. FIRE RETARDING PROPERTIES: SINGLE FINISH As a single finish, metal lath on wood supports and with a %-in. three-coat gypsum plaster coating when exposed on the finished side to standard fire test conditions, will delay active combustion of its wooden supports for about 45 min., after which period it will continue to prevent the passage of flame through the finish up to at least one hour’s total fire exposure. Upon application of a standard fire hose stream, during or im- mediately following fire exposure, the fire retarding properties of such a single finish will be almost entirely destroyed after 30 min. of such fire exposure. DOUBLE FINISH When installed on both sides of a partition frame or wall frame of wood studs, the construction either may serve as non- bearing or may be called upon to bear a certain proportion of both dead and live loads from the floors above. The following conclusions are based upon the assumption in either case that complete flre-stopping within hollow spaces is provided : — NON-BEARING PARTITIONS OR WALLS— Metal lath with 5^-in. three-coat gypsum plaster coatings when installed on each side of the wood studs comprising the framework of non- bearing partitions or walls which are exposed on one side to standard fire test conditions will prevent the passage of fire through the partition or wall for upwards of one hour and will function as a barrier to passage of flame and spread of fire for at least one hour when subjected on one side to the impact and erosion of standard fire hose streams applied any time up to one hour from the beginning of the fire exposure period. The fact that the combustible frame of the partition or wall will be burning within the 1-hr. period (about 45 min.) should have consideration, but does not detract from the performance of the construction as a fire retardant up to the limiting period. BEARING PARTITION OR WALL— Metal lath with %-in. three-coat gypsum plaster coatings when installed on each side of studs comprising the framework of bearing partitions or 69 CONCLUSIONS walls and when exposed on one side only to standard fire test conditions will prevent the passage of fire through the partition or wall for the entire period during which studding of the di- mensions ordinarily employed (2 by 4 in. or 2 by 6 in.) will sup- port its load. After 45 min. exposure on one side to standard fire test conditions reduction of section and loss of strength of the wood supports from charring and from active combustion takes place. The construction, when employed as a bearing partition or wall, will function, while loaded, as a barrier to the passage of flame and spread of fire for at least 1 hr. when subjected on one side to impact and erosion by standard fire hose streams applied any time up to 1 hr. from the beginning of the fire exposure period. The fact that the combustible frame of the partitions or wall will be ignited in about 45 min. of fire exposure should have consideration, but does not de- tract from the performance of the construction as a whole as a fire retardant up to the limiting period. This conclusion is based upon the results of the Fire En- durance Tests and the Fire and Hose Stream Tests, and upon the evidence of the readings for bulging or distortion in the Fire Endurance Tests to the effect that no strains were placed upon the load bearing members because of expansion effect of heat on these members, the m.etal lath or the plaster coat. A construction employing wood studs, stills, plates, braces and similar units is quite generally permitted for relatively light loads, as in residences, as a bearing wall or partition. When loaded not to exceed 50 lbs. per sq. ft. of supported floor area (for 2 by 4-in. studs on 16-in. centers) calculations (see “Claims Made by the Submittor’’ in Appendix IV) show a fair factor of safety which may be taken into consideration in con- nection with the extent of fire damage to the wooden sup- ports. The panel used for the Eire and Hose Stream Test was subjected to a standard fire exposure for 45 min., promptly whereupon the hose stream was applied, extinguishing all fur- ther burning of the wood frame. Examination then made showed the edges of studs on the side of the panel exposed to the fire charred in places to a depth of %. in. The opposite edges and the sides of the studs were not yet affected, although it was evident that the ignition point had been nearly reached. The panel used in the Eire Endurance Test No. 2 was sub- mitted to a standard fire exposure for 75 min., promptly where- upon the hose stream was applied, extinguishing all further burning of the wood frame. Examinations then made showed that the edges of the studs on the side of the panel exposed to the fire were charred from a mere discoloration to a depth of W in. in places. The opposite edge was not yet affected, but 70 STABILITY AND FIRE STOPPING the sides were charred slightly near the exposed edge where the charring was most markedly on the exposed face. Other calculations (see Claims Made by the Submittor) show reasonably high factors of safety remaining when char- ring has occurred to a depth of % in. on two faces of studs. On this basis and in view of the fact that the strength of the un- charred portion of the cross section of a v/ood stud remains practically unimpaired, and in view of the fact that material ex- pansion under heat and contraction upon cooling are not proper- ties of wood, of which material the load bearing units of this construction are made, a conclusion relating to fire retarding properties of the construction when loaded may properly be made if based, upon the observed condition at the end of the Fire Endurance Test No. 2 or the period before active burning of the wooden supports had begun. This direct and possibly severe basis for such a conclusion is necessarily employed since apparatus for testing walls or partitions under standard fire test conditions and while bearing rated loads is not available at the plant of Underwriters’ Laboratories, and data covering re- sults of such test, if any, made elsewhere, is not available. Wood Joist Floor and Ceiling Construction — The following conclusions .are based upon the assumption that complete fire stopping within the hollow spaces is provided. A wood joist floor construction utilizing a metal lath and gypsum plaster ceiling finish, when exposed on the ceiling side to standard fire test conditions, will for at least one hour safely sustain its rated load and suffer no serious reduction of strength or of cross section area of combustible load bearing units and will prevent the passage of fire through the assembly for at least one hour unless previously subjected on the ceiling side to the impact and eroding effect of standard hose streams. Upon application of hose streams after 30 min. standard fire test exposure the gypsum plaster finish will be destroyed. The fact that the combustible units of the construction will be burning within the 1-hr. period (about 45 min.) should have considera- tion, but does not detract from the performance of the assembly as a fire retardant up to the limiting period. These conclusions are based on the Fire Endurance Tests and Eire and Hose Stream Tests as outlined in previous chap- ters of this report. A floor construction employing wood joists is quite gen- erally recognized for relatively light loads as in residence, of- fice and small mercantile occupancies. When loaded not to ex- ceed 50 lbs. per sq. ft., 2 by 10 in. joists, 16-in. centers, show a fair factor of safety (See Claims Made by Submittors), which 71 CONCLUSIONS may be taken into consideration in connection with the extent of the fire damage to the wood joist. The sample used in the Fire Endurance Test was subjected while loaded, 50 lbs. per sq. ft, to standard fire conditions for 75 min. Promptly thereupon water was applied, extinguishing all further burning of the wood members. Examination then made showed the edges of the joist exposed to the fire charred in places to a depth of 3 % in. The sides of the joist adjacent to the exposed edge were also charred and the remainder of the sides of the joist and underside of the rough flooring were discolored and slightly charred in a few spots. In view of the fact that the strength of the uncharred portion of the section of the wood joist remains practically unimpaired, a conclusion relating to the fire resisting properties of the construction when loaded may properly be made if based on the observed con- dition at the end of the Fire Endurance Test. The regularly adopted Standard Specifications for Eire Tests of Materials and Construction contemplate, dn the case of floor constructions, that test specimens shall be subjected to fire exposures from the ceiling side only. This procedure has been followed in this case and the retardant classification pro- posed is on that basis and the foregoing conclusion is so stated. STABILITY: The constructions under consideration comprising metal lath and gypsum plaster on wood supports will develop the fire re- tarding classifications assigned elsewhere in this report when the metal lath is supported by the 6-penny 2-in. nails for ceil- ings and 4-penny nails or 1^-in. staples spaced on an average of 6 in. for partitions (and without supplementary at- tachments as originally contemplated, see Appendix I). Observations during and after tests both upon partition and wall specimens and upon the floor construction, show practical absence, in the case of specimens having gypsum plaster coat- ings, of serious bulging, cracking or spalling, the effects of ex- pansion forces due to temperature rise. WHEN FIRE STOPPING IS OMITTED: Mention has previously been made of “fire-stopping” as a basic condition of the foregoing conclusions relating to the fire retarding properties of constructions comprising metal lath and gypsum plaster on wood supports. In every case assemblies exposed to standard fire endurance and to fire and hose stream tests as described in this report were completely firestopped. 72 STABILITY AND FIRE STOPPING In this respect the test conditions approximated ideal conditions and were far superior to representative good fire stopping as done in the field. Absence of fire stopping will have no influ- ence upon the fire retarding performance of the constructions considered in this report up to the point when ignition of the combustible wood supports takes place. Thereafter without fire stopping the progress of fire within concealed spaces will be impeded very slightly, if at all, by the nature of the units employed in the described assemblies. The Fire Endurance Test No. 2, and the Fire and Hose Stream Test of the wall and partition constructions and the Fire Endurance Test of the » floor construction utilizing gypsum plaster show incipient char- ring of wood supports at about 45 min. standard fire test ex- posure. When fire stopping is omitted the constructions covered by this report utilizing metal lath ^and gypsum plaster on wood supports will resist an exposure from standard fire test condi- tions for 35 min. before ignition of combustible material in con- cealed spaces will occur. 73 SECTION IV APPENDIX I Retardant No. 1355 August 10, 1922 BRIEF SUMMARY OF TESTS ON WOOD JOIST FLOOR CONSTRUCTION WITH Metal Lath and Portland Cement Plaster Ceiling Finish Associated Metal Lath Manufacturers, Chicago, 111. National Lumber Manufacturers’ Association Chicago, 111. Washington, D. C. Joint Submittors GENERAL: The following is a brief summary of the results of Fire En- durance, Fire and Hose Stream Test and Excess Load Tests on Wood Joist Floor Construction with a Metal Lath and Portland Cement Plaster Ceiling Finish. In other respects the samples were constructed practically similar to the samples de- scribed in Section 11. The test program followed the Standard Specifications for Fire Tests of Materials and Construction de- scribed in Appendix VII. FIRE ENDURANCE TEST: DESCRIPTION OF SAMPLE The sample was constructed similar to that described for the Fire Endurance Test of the gypsum plaster construction, except that the pieces of No. 8 annealed wire about 30 in. long were bent in the form of a loop and inserted over the second joist from each end of the room and over each joist 2 ft. from the east and west walls and along the middle joist. The loops were spaced at 2 ft. centers on each of the two joists along the second joist from each end and along middle joist. They engaged the metal lath and were intended to support the ceil- ing finish in case the nails or staples pulled as the result of expansion forces under test conditions. The Portland cement plaster was applied in three coats ac- cording to the usual practice for portland cement plaster on metal lath. The proportion was three parts of sand and one of Portland cement with an allowance of 10 per cent of hydrated lime to the weight of portland cement. A small amount of ani- 74 FIRE ENDURANCE TEST mal hair was used in the first coat. The finish was about in thickness. The sample was 29 days old when tested and had been allowed to season for 21 days in freely circulating air inside a wooden building; was subjected to ordinary autumn weather in this locality, from October 18 to November 16, 1920, where it was possible for the temperatures to go below the freezing point for the short periods during the latter part of the seasoning period. From the 21st to the 25th day of the seasoning period the sample was dried by two salamanders installed on the outer side of the sample and the heat was directed through an opening in east and west wall into the chamber which* con- tained the cement finish. The heat was circulated into the in- terior by two electric fans. During the last four days the side walls were closed up and the wooden building was removed in order to apply the brick load. After the brick load was ap- plied several longitudinal hair cracks were noted in finished ceiling. The largest of these cracks extended the full length of the ceiling about 55 in. from the east wall. Another broken series of longitudinal cracks were noted in north portion of the ceiling. The width of these cracks did not exceed 1-32 of an inch at any point. The appearance of the test panel with the load applied be- fore test is shown by Fig. 42. METHOD The standard test equipment described in Appendix VI was used in this test. The test sample was subjected to a uniformly distributed live load of 50 lbs. to the sq. ft. This load consisted of new com- mon Chicago brick piled in rows spaced about ^ in. apart. The apparatus for measuring furnace pressures and tempera- tures and for measuring deflections in the test panel were in- stalled and the fire started. The lower face of the test panel was exposed to the standard fire conditions in which the tem- perature was raised to approximately 1550 deg. F. during the first 30 min. to approximately 1700 deg. F. at the end of 1 hr., and then gradually upward until the end of the test. The test was continued for 1 hr. and 35 min. when the fire in the furnace was extinguished, this being approximately 30 min. longer than 1 hr. period for which classification was de- sired. The top of the test panel was flooded with water from a small stream in an effort to extinguish the fire in the hollow spaces and to permit detailed examinations of the parts, a portion of the east wall of the furnace was knocked out to per- mit access for extinguishing the fire. A hole was also punched through the metal lath and plaster in an effort to render the 75 • APPENDIX I— FLOORS AND CEILINGS interior accessible for extinguishing of the fire, but the fire on the interior continued to burn until the floor collapsed. Observations were made during and after the test covering the distribution and general character of the fire, the color of the parts due to heat, the deflection of the test panel, and the pressures and temperatures in the furnace, to obtain informa- tion relative to the effect of the fire on the strength of the parts and the floor and its flame and heat resistance. RESULTS The following is a summarization of the results observed during and after the test: The appearance of the test panel before and after the test is shown by Figs. 42 and 43. The average indicated tempera- tures in the furnace are shown by the curve in Fig. 44. Character of Fire — The fire was clear and semi-luminous during the first 30 min., but was somewhat unevenly distributed during this period, the exposure being more severe in the north half. The fire was clear and luminous and uniformly distrib- uted during the remainder of the test. The surface of the panel began to show color in spots at 20 min., was dull red in all parts at 30 min., became bright red at 60 min. and re- mained so until after the gas was shut off at 95 min. No pres- sure above atmosphere was noted in the furnace during the test. The average furnace temperatures were slightly below the standard temperatures and are shown by the time-temperature curve in Fig. 44. After the gas was turned off, long luminous flames issued from the cracks in the plaster, nearly filling the furnace with flame. This continued intermittently for probably in excess of 30 min. The fire continued to burn in the hollow spaces until the floor collapsed at about 2^ hrs. after the start of test. Cracks, Spalling, Bulging and Deflection — The finish coat of plaster commenced to spall off min. after the fire was started and continued to be thrown off at various parts of the sample, until 7 min., when about one-quarter of the finish coat was off in patches of various sizes in several parts of the panel, the largest single dislodgement being about 3 by 7 ft. in the north half. The scratch and second plaster coats remained in place until the end of the test and were apparently well bonded, together and to the lath. At 30 min. a crack was noted extending east and west clear across the panel close to the middle, and at 35 min. a diagonal crack about 14 in. long was noted near the southeast corner. At 50 min. 2 longitudinal cracks, 18 to 24 in. long, were noted between the middle crack across the middle, at 55 min. another north and south crack appeared in the locality and at 80 min. still another, the latter being near the middle 76 FIRE ENDURANCE TEST of the panel. These cracks were undoubtedly body cracks and became gradually wider as the bulging increased, and were ap- parently about in. wide at the surface of the plaster at 90 mih. At 35 min. the lath and plaster coating was bulging down- ward slightly, near the southeast corner, and at 40 min. the plaster coating was irregularly bulged,, the bulging being most marked in the south half where it amounted to about 2 in. Irregular bulging increased to a maximum of about 3 in. at the cracks at 50 min. At 60 min. irregular bulging had reached a maximum of about in. in the north half and about 4 in. in the south half. The maximum downward bulging was at points approximately midway between the supporting wires. The deflection of the floor at the middle of the panel before test was 0.11 in., 72 hrs. after a uniformly distributed live load of 50 lbs. to the sq. ft. was applied, or about 0.34 in. less than the computed deflection. After the fire was started the de- flections gradually increased to 1.86 in. exclusive of initial de- flection when the fire was extinguished. This increase in de- flection was nearly coincident with the appearance of bulging. The condition of the assembly after test is shown by Fig. 43. Flame Resistance — On the upper face of the test panel, steam issued from a slight crack in the floor boards at 43 min. Steam was also noted east of the middle and in the northwe.st corner of the panel during the 45 to 55 min. period, continuing to issue .at these points during the test. At 60 min. slight smoke was noted at the above points and also in the southwest corner. At 75 min. smoke issued along the north and south edges and at 85 min. along the east and west edges of the test panel. The smoke issued at these points during the remainder of the 1-hr. 35 min. period when the furnace was in operation. It increased very much in volume at the edges of the panel after this period until the end of the test. At about hrs. after the test was started, slight flame was noted near the middle of the west edge of the panel. This flame was intermittent, came from the fire on the interior of the floor, and issued through a separation at the fire stop at the ends of the joist caused by the marked sagging of the floor at this period. The test panel collapsed under the load at about 2^ hrs. The entire wooden floor was practically consumed except small sections of the flooring, furring strips, joist and insulation along the edges and ends. The wooden girders along each side of the restraining frame were in normal condition, the two joist along the north and south side of the restraining frame were only charred about in. along the side. This good condition was due to the protection afforded by the 6-in. 77 APPENDIX I— FLOORS AND CEILINGS gypsum blocks which were placed in the outside of these members. On examination of the sample after test, the finished coat was practically all knocked off except small areas along the sides and edges. The other two coats were badly cracked but appeared to have retained most of their original strength. A good key was formed in the back face of the lath and aver- aged about 34 in. in thickness, which formed an irregular coat of plaster on the back face of the entire ceiling. These keys, reinforced by the metal lath, apparently strengthened the finish to a considerable extent. The metal lath was separated longitudinally of the ceiling. This separation was due to the reinforcing wires separating and allowing the ceiling to collapse in two sections. The metal lath appeared in good condition, but the reinforcing wires be- came annealed at two points and pulled apart, due to the heal and excessive load which they were called on to carry aftei the joist had collapsed. These separations were formed mid- way of each of the north and west walls of the sample. The loops and other parts of the reinforcing wires appeared to hold their position in all cases. The observations on the exposed face of the panel indicated that no flame passed into the hollow spaces and that the joist and wooden members were ignited by the transmission of heat rather than the passage of flame. The time at which the joist took fire could not be ascertained, although it is probable that this occurred within about 60 min. A tar-like substance was noted running down on the outside wall of the furnace in the southwest corner at 65 min. and considerable smoke issued from the underside of the panel in this corner at 70 min. THe edges of the cracks in the plaster were also blackened by tar or similar substance distilled out of the wood at about this period and remained so until the furnace fire was shut off at 95 min. The floor was apparently well afire on the inside at this time as long gas flames issued from all cracks and filled the furnace chamber with flame, although all other fuel was shut off. The fire in the furnace chamber was extinguished by a small hose stream applied at short intervals for over hr., but the gases generated by the fire on the interior of the floor reignited by contact with the heated furnace during this pe- riod unless the stream of water was almost constantly applied. A small hole was punched through the lath and plaster near the east side of the panel at about 2 hrs. and fire was discovered on the interior. Under these conditions it was found imprac- ticable to remove sufficient lath and plaster to permit ex- tinguishment of all of the fire in the woodwork, so it was al- 78 Figure 42 View of sample mounted in furnace ready for Fire Endurance Test with load of 50 lbs. per sq. ft. applied, showing deflection targets and furnace thermocouples connected up to junction box ready for test. Figure 43 View looking west in furnace, showing condition of floor after col- lapse of sample into the furnace chamber. 79 APPENDIX I— FLOORS AND CEILINGS lowed to burn until the floor collapsed about 2^ hrs. after the start. Heat Resistance— The observations on top showed that the transmission of heat through the assembly was very slight throughout the entire test. The general appearance of this face of the panel when the gas was shut off at 1 hr. and 35 rnin. was practically the same as before the test, except that sufficient heat passed through the floor at the points where steam and smoke were noted to melt patches of snow and dry off the boards in one small area. After the furnace was shut off a small stream of water was applied to the upper side so that it would leak through the boards and aid in the extinguishing of the burning interior. This water settled to the middle and was retained to a depth of 3 or 4 in. for some time, adding to the load on the floor. The "bricks also absorbed considerable water and thus still further increased the live load. 80 FIRE AND HOSE STREAM TEST: DESCRIPTION OF TEST SAMPLE The test sample employed in this test was constructed prac- tically identical with and was mounted in the same manner as the panel used in the Fire Endurance Test. It was 44 days old when tested and had received the same treatment as the panel previously described except that four salamanders were kept going on the outside of the test sample during and for four days after the installation of the plaster, in order to keep the temperatures above the freezing point as, this sample was allowed to season from February 14 to March 30, 1921. The sample was firm and apparently in a normally dry condition and free from cracks or visible separations* likely to affect its fire resistance. The finish on the ceiling averaged about % in. in thickness on the outer surface of the lath. The average length of the finished floor was 17 ft, 5^ in. and the average width of the floor was 13 ft, 634 in. The average length of the finished ceiling exposed to the fire was 15 ft, 734 and the average width was 11 ft., in. The appearance of the test sample before test with the brick load applied is shown in Fig. 45. METHODS The Laboratories’ standard test equipment described in Ap- pendix VI was used in this test. The test panel was subjected to uniformly distributed live load of 50 lbs. per sq. ft. This load consisted of common Chi- cago brick piled in rows spaced about 34 in. apart. A specially designed ^-in. open sprinkler arrangement was provided at each end of each joistway during the installation. This was installed to overcome the difficulty experienced with the Fire Endurance Test sample which, due to lack of some method of extinguishing fire in the joist ways, was practically consumed in the test. The test sample was subjected to the standard fire test for 45 min., after which the gypsum walls along the east and west wall were torn away and a in. stream of water applied to the heated face of the plaster finish for about 5 min. The stream was applied from about 12 ft. from the center of the panel and about 3 ft., 6 in. below its ceiling surface. It was first directed at the middle of the sample and then at all parts of the exposed face, changes in the direction of the stream being made slowly. The pressure at the base of the nozzle was 45 lbs. per sq. in. throughout the test. Observations were made throughout the fire test covering the distribution and general character of the fire, the color of the test panel due to heat, the deflection of the test panel, the 81 APPENDIX I— FLOORS AND CEILINGS furnace pressures and temperatures in the furnace and at seven points within the construction which were symmetrically spaced, one near the middle of the center joistway and one, two joist- ways on either side of the middle point. The other four tem- peratures were taken at the quarter points between the second and third joistway from each end of the sample. Observations were made during and after the test to ob- tain information relative to the effect of the fire and water on the strength of the parts and the floor as a whole and rela- tive to flame and heat resistance. • RESULTS The following results were observed during and after the test, the developments relating to each feature and the con- clusions drawn therefrom being given under their respective headings. The appearance of the test panel before and after test is shown by Figs. 45 to 56 inclusive. The average indicated temperatures in the furnace and in the joistways is shown by Fig. 57. Character of Fire — The fire was fairly well distributed over the under face of the sample throughout the test. It was some- what less severe on the edges than at the middle and during the first part of the test it was most intense over the burners. Falling plaster partially choked several burners directly below the portions of the panel from which the plaster fell. There was very little direct impinging of stiff flame jets on the panel, although this was noticeable for short periods when the burn- ers were first lighted. The fire was semi-luminous for the first 15 min. of the test, generally clear but smoky in places during the 15 to 20 min. pe- riod, clear during the 20 to 25 min. period and generally clear filling the chamber from that time on. The panel was lumin- ous in spots at 10 min., showed a trace of color all over in ten min., dull red all over with brighter spots in 20 min. and red all over with soot spots in 25 min. As the test progressed the color became brighter and the spots gradually disappeared. Cracks, Spalling, Bulging and Deflections — The plaster coat- ing commenced to spall at 8 min., throwing off the plaster fin- ish from an area about 3 ft. wide and 8 ft. long, exposing the metal lath and apparently allowing fire to enter the hollow spaces between the joist. Another explosion occurred at 13 min. increasing the original opening into the interior. A slight bulge was noted at 20 min. No other cracks or separations were noted during the test. 82 FIRE AND HOSE STREAM TEST The deflection at the middle of the sample was 0.20 in. 88 hrs. after the load of 50 lbs. per sq. ft. was applied or about 0.20 in less than the computed deflection. During the test the deflection not including the deflection before test, gradually increased to about 0.51 in. at 45 min., when the furnace fire was shut off and the deflection after the water stream was applied was 0.88 in., and was 0.91 in. after the sample was allowed to cool for 22 hrs. Five days after the load of 50 lbs. per sq. ft. was removed, the total deflection was 0.82 in., including the deflection before test. Flame Resistance — When the test had been in progress 8 min., there was a muffled explosion and the plaster forming all but the scratch coat fell off of an area estimated to be 8 ft. long and 3 ft. wide. The scratch coat fell off in spots inside this area exposing the metal lath in several places and apparently permitting flame to enter the concealed space between the joists. At 13 min. there was another explosion and consider- ably more lath was exposed and the area from which plaster had dropped increased to some extent. At no time during the tests were any cracks visible in the sample or any separations or dislodgements other than those mentioned. At 20 min. the panel appeared to have a slight general bulge and the surface appeared somewhat irregular. The application of the stream washed away all of the finish coat of plaster and increased the area of exposed lath but did not throw off any large pieces. Except the finish coat and the part previously loosened by fire, the remaining plaster re- mained securely in position. The special sprinkler arrange- ment installed between joists was operated after the wat 'r stream was applied and all burning parts were extinguished in the hollow spaces at about 55 min. On the unexposed side of the sample steam appeared around the outer edge of the sample at 7 min., appearing at other points at 10 min. and increasing in volume at 30 min., when con- siderable steam was issuing along the south edge adjacent to the area where the plaster had fallen from p,osition. A slight odor of burning wood was apparent from the south edge of the sample at 15 min. and slight traces of smoke mixed with steam were noted at 20 min. A slight increase in the volume of this steam and smoke was noted along the south edge of the sample during the remainder of the test. There was no apparent passage of flame through or around the sample during the test. The condition of the unexposed side of the sample after test is shown by Figs. 45 and 47. On examination of sample after test and during the dis- mantling of the same, the finished floor was found only slightly 83 APPENDIX I— FLOORS AND CEILINGS discolored in the south edges where steam and smoke passed around the outer edges between the restraining frame of the furnace and test sample. Slight scorching of the under side of the finished floor was noted immediately above the insula- tion where the plaster fell from position. The nails held their position in all cases. The condition of the finished floor after the brick load was removed is shown by Fig. 47. The furring strips were undamaged and remained in posi- tion but were slightly discolored. The condition of the furring strips after test is shown by Fig. 48. The insulation appeared in normal condition after test ex- cept immediately above the area where the fire charred the rough flooring. The condition of the insulation after test is shown by Figs. 48 and 56. The rough flooring was in normal condition except in the areas where the plaster was dislodged. The charring in the damaged area varied from a mere discoloration to a complete charring at two points between joistways four and five from the south edge of the sample. The condition of the rough flooring after test is shown by Figs. 49 and 50 inclusive. The bridging was completely charred in the damaged area and the fire stream washed away part of the charred sections. The bridging in the remaining sections of the floor was normal in appearance and held its position in all cases. The joist was charred from a mere discoloration along the sides of the joist to almost 45 per cent of the total cross sec- tional area where the fire first broke through the cement plaster finish. A permanent maximum downward deflection of in. was noted near the middle of the center joist and gradually de-. creasing toward each end of the sample. The condition of the joist and bridging after test is shown by Figs. 51 to 53 inclusive. After the test the metal lath and portland cement plaster bulged slightly away from the under side of the joist except where the finish was reinforced and held in position by the loops which were attached over the top of the joist. A slight bulge was noted between the wire loops; the maximum being almost in. near the middle of the center joist. The nails securing the lath to the joist pulled from position in the joist inside the area reinforced by the heavy wire. The maximum deflection of the finish away from the joist was 4l4 in. in dam- aged area. 84 FIRE AND HOSE STREAM TEST A good key was formed on the back face of the lath which was covered in all cases with the scratch coat mortar. The en- tire finish coat was spalled or washed off during the test. The other two coats were firm and apparently retained the greater part of their original strength except in the spalled area. The plaster contained several small surface cracks in the area where the plaster remained in position. Small cracks were noted at the junction between the wall and ceiling, but these did not allow fire to enter the interior of the floor; the}^ were not con- sidered serious from a fire protection viewpoint. The condition of the ceiling after test is shown by Figs. 52 to 55 inclusive. Heat Resistance — The extent of the heat insulation afforded by the plaster was not clear from observation on the fire side, but it was noticeable that very little smoke or gas reached the furnace chamber from interior of the sample. It appeared that the falling plaster must have exposed the wood work at about 8 min. and the exposed metal lath was red hot at 15 min. The temperatures in the sample are shown by Fig. 57. 85 EXCESS LOAD TEST: DESCRIPTION OF SAMPLE The test sample used in the Fire and Flose Stream Test was used in this test. The brick load was removed and the sample was allowed to stand for about five days. The condition of the sample after the removal of the brick load used in the Fire and Water Test and before the excess load of 125 lbs. per sq. ft. was applied is shown by Fig. 47 . METHODS The test sample was subjected to a uniformly distributed live load of 125 lbs. per sq. ft. This load consisted of common Chicago brick piled in rows spaced about % in. apart both ways. Readings were taken at 1 hr., after loads of 50 lbs., 100 and 125 lbs. per sq. ft. were applied and again after the load had been applied about 46 hrs. and 16 hrs. after the load was re- moved from the sample. Observations were made during and after the application of the excess load to obtain information relative to the following features, strength of parts as indicated by the brick load sus- tained, the deflection under load, the development of cracks, insecurity in attachments or other evidence of weakness and by the condition of the floor after the load was applied and removed. RESULTS The following results were observed during the progress of the test and examination afterwards. The appearance of the floor before and after the excess load was applied is shown in Fig. 47 and the appearance of the sample with the load applied is shown by Fig. 46. The sample assumed a permanent set after the initial fire test loading (50 lbs. per sq. ft.) of 0.82 in. and this permanent set is not included in the following computation. The deflection at the middle of the sample one hr. after the application of a live load of 50 lbs. per sq. ft. was 0.24 in., 100 lbs. per sq. ft. was 0.44 in. and 125 lbs. per sq. ft. was 0.49 in. and the total deflection after the load had been applied 46 hrs. was 0.57 in. The reading 16 hrs. after the load was re- moved was 0.07. A slightly greater deflection was recorded in the area directly above the point where the finish was dislodged and the joist was exposed to the direct action of the fire. The deflection at this point 46 hrs. after the load had been applied was 0.58 in. and the reading after the load had been removed 16 hrs. was 0.12 in. 86 Figure 45 View looking west, of sample used in Fire and Hose Stream Test before test, with load of 50 lbs. per sq. ft. applied. Also location of interior and furnace thermocouples connected to junction box and deflection targets in position. Figure 46 View looking west showing excess load 125 lbs. per sq. ft. (2^/i times safe rated load) after being subjected to standard fire condi- tions for 45 min. and then a hose stream of 30 lbs. per sq. in. was applied for 5 min. 87 Figure 47 View looking west showing top flooring before Fire and Hose Stream Test, after Fire and Hose Stream Test and after excess load of 125 lbs. per sq. ft. was removed. Figure 48 View looking west showing furring strips and deadening felt after finished floor was removed after Fire and Hose Stream Test 88 Figure 49 View looking south, showing top surface of rough flooring in the damaged area, after Fire and Hose Stream Test. Figure 50 View looking south, showing underside of rough flooring in the damaged area after Fire and Water Test. Boards turned over in the same relative position showing damaged area and smoke stains. 89 Figure 51 View looking south, showing joist and bridging in the damaged area after Fire and Hose Stream Test, rough flooring removed. Figure 52 View from above, showing condition of joist bridging and metal lath and cement plaster finish in the damaged area. 90 Figure 53 View from above, looking into joist bays showing condition of joist bridging metal lath and portland cement finish in north undam- aged section of floor after Fire and Hose Stream Test. Figure 54 View looking west and upwards, showing condition of north section of metal lath and portand cement plaster finish after Fire and Hose Stream Test, west walls removed. The mottled effect is from the moisture due to the Hose Stream Test. 1)1 Figure 55 View looking west showing the condition of the south or damaged area of the metal lath and Portland cement finish after the Fire and Hose Stream Test, west wall removed. Figure 56 View showing condition of deadening felt immediately above the damaged area in the rough flooring after Fire and Hose Stream Test 92 EXCESS LOAD TEST Observations during and after the test indicate that the va- rious units and fastenings possess sufficient strength to with- stand a live load of 125 lbs. per sq. ft. which is two and one- half times the safe rated load for floors of this class without deflecting at the middle sufficient to cause any marked open- ing in the small cracks which were formed in the ceiling finish during the Fire and Hose Stream Test. The results show the specified factor of safety in strength of the wood joisted floor construction finish with metal lath and portland cement plaster under a normal live load of 50 lbs. per sq. ft. 93 APPENDIX II TRANSVERSE LOAD TESTS ON METAL LATH AND GYPSUM PLASTER CONSTRUCTION: DESCRIPTION OF SAMPLES Two test panels, each having a plastered area 36 in. by 50 in., were employed in these tests. Each panel comprised a rectangular framework of wood members, serving as a support for wire lath and gypsum plaster. Each panel was made up of four studs, nominally 2 by 6 in., approximately 42^ in. long, spaced 16 in. center to center, with one 2 by 6 in. piece, 50 in. long, nailed across each end of the row of studs and preserving their relative positions. One face of the framework formed by the studs carried 2 sheets of No. 26 U. S. gauge diamond-mesh wire lath, 50 in. long, one sheet being 20 in. wide and the other 14 in., lapped 2 in. to provide a total with of 36 in. The metal lath was attached to the studs by No. 14 B. W. G. (.083-in.) staples, spaced 4 to 43 ^ in. At the lapped portion the two sheets were secured to- gether by No. 18 B. W. G. (.049-in.) galvanized steel tie wire. The plaster was 3-coat work, applied with ^-in. grounds. The scratch coat was a mixture of 1 part Imperial plaster and one part sand by volume; the brown coat was a 1 to 2 mixture. The brown coat was applied about 48 hrs. after the scratch coat; the finish coat about 72 hrs. after the brown coat. The panels were 7^4 months old when tested. METHOD Each panel was tested separately in the Laboratories’ 10,000-lb. Olsen testing machine, which was provided with special attachments for transmitting load to the sample and for indicating deflections. Each panel was mounted in a horizontal position with its plastered surface uppermost and was loaded by means of a bar in contact with the center line of the panel, and therefore midway between two studs. Load was applied by increments of 50 lbs. and all results were noted. RESULTS Panel No. 1 Observations During Test — During the application of the load the finish deflected gradually to a maximum of about 34 in. at 1,000 lbs. Rather rapid deformation at this time caused the load to decrease to about 800 lbs. Continual increase in the load to a maximum of 1,200 lbs. caused a deflection of about ^ in. Continual operation of the testing machine resulted in the rapid increase of deflection to about 3 in. with continually diminishing load. 94 TRANSVERSE LOAD TESTS Slight cracking near the middle of the panel occurred at loads of about 600 and 700 lbs. At 1,000 lbs. large cracks de- veloped along the line of application of the load and above each inner stud. Condition After Test — Large cracks extending the entire width of the panel were formed along the line of application of the load and over each of the two inner studs. The lath was ruptured along an irregular line following the general direc- tion of the loading line, the mesh having elongated consider- ably before failure. The brown and scratch coats could be easily separated everywhere in the middle third of the panel. Panel No. 2 Observations During the Test — During the application of the load the finish deflected gradually to a maximum of about 0.10 in. at 850 lbs. Rather rapid deformation at this time caused the load to decrease to about 800 lbs. Continued increase in the load to a maximum of 1250 lbs. caused a deflection of about Yz in. Continued operation of the testing machine re- sulted in the rapid increase of the deflection to about 2^/2 in., with continually diminishing load. No apparent cracking occurred at loads less than 850 lbs. Under this load large cracks developed along the line of appli- cation of the load and above each inner stud. CONDITION AFTER TEST The condition of the sample was similar to that reported for Panel No. 1. 95 APPENDIX III SPECIFICATIONS for PREPARATION AND INSTALLATION of METAL LATH AND SANDED AND WOOD FIBERED GYPSUM PLASTER CONSTRUCTION on WOOD SUPPORTS The material for the studs, sills, plates and supports is usually shipped to the job in random lengths. The metal lath is furnished in bundles, the staples in packages or kegs, the wire in- coils, the spot grounds in boxes, the metal corner bead- ing in bundles, the plaster in bags and the sand in bulk. The frames, doors, sash and some of the standing finish are as- sembled at the mill and delivered to the job in separate units braced to prevent injury in handling. The running trim is often delivered in random lengths. Installation of Studs, Trusses and Fire Stops — The studs are usually installed after the floor joists and rough flooring are in place. They are cut to length, the sills and plates nailed in place and erected in position as shown by the plans. They are then set plumb and true to the line and held in position by temporary bracing until the next floor joists are in position on the plates, the joists being well spiked to the plates. The trusses are then installed over the openings, and the grounds nailed to the rough framing around the openings. The fire stops are securely attached in proper position between the studs and other details of the partition framing completed. Application of Lath — The lath is installed after the building is closed in. The sheets of lath are attached to the studs in horizontal courses beginning at the top. The upper sheets are bent so that they lap the ceiling joiilt at least 6 in. to reinforce the corners and prevent cracking in the plaster. Each suc- cessive course is laid so that its upper edge overlaps the lower edge of the preceding course at least ^ in. so as to present no obstruction to the plastering trowel. The edges at the ends of the sheets are also overlapped at least 1^ in. and the sheets bent so that they overlap adjoining surfaces at least 4 in. at the angles with walls and partitions. The vertical joints be- tween the sheets are broken at each course. The lath is cut close up to the grounds at the floor and framing at the open- ings. It is attached to each stud to which it is secured by 1^ in. staples or by l^^ in. nails driven partly in and bent over and spaced not exceeding 8 in. 96 METAL LATH AND PLASTER CONSTRUCTION Metal lath is attached to ceiling supports by not less than 6-penny, 2-in. nails driven partly in and bent over and spaced at not exceeding 6 in. centers, 'when the supports are spaced at not exceeding 16 centers. Metal lath for interior walls and partitions should 'weigh not less than 2.5 lbs. per sq. yd. or 26 U. S. gauge steel and for ceilings not less than 3.0 lbs. per sq. yd. or 25 U. S. gauge steel. The metal lath to be of the expanded diamond mesh patterns. The overlapping edges of the sheets are tied 'with No. 18 gauge annealed tie 'wire mid- ■way between supports. Where large coves are provided at the junctions between partitions and ceilings, the metal framing is first securely nailed to the studs and joists. The lath is then attached to the fur- ring by tie wire so as to form the curved base for the plaster. Small coves are usually formed of solid plaster formed to the desired design. The metal corner beading is nailed to the supports at the outside angles of the walls and partitions. Preparation of Sanded Gypsum Plaster — The gypsum plas- ter is stored in a clean, dry place until used and is mixed in batches that can be used within one hour after mixing. The proper proportions of sand and plaster are obtained by any con- venient method of accurately measuring these materials. Only clean water free from alkali and impurities is used. The mix- ing box, mortar boards and tools are kept well cleaned, to pre- vent the mixing of one gauging of plaster with another. The plaster to consist of two parts by weight of clean, dry, sharp sand to one of neat gypsum plaster. Hair or plastering fiber to be added as desired for the coat. The plasters for the scratch and brown coats are mixed by placing a layer of sand in the mixing box and then a layer of plaster in the proportions specified, and mixed dry. Water is then added and the dry mixture hoed back and mixed into the water until a thin plaster of uniform consistency and appearance is secured. Sufficient dry plaster and sand in the proper proportions are added and thoroughly mixed in until the plaster is of the proper consistency for application. The plaster is never retempered and used after it has commenced to set. The lime putty finish is usually mixed on a mortar board, using a lime putty made from thoroughly slacked quick lime or hydrated lime mixed with water and allowed to stand for about 24 hours. A ring of lime putty about 2 ft. in diameter and 6 in. high is first formed on the mortar board, about 4 in. of water is poured into the ring and the dry calcined gypsum then sifted into the water in the proper proportion. After the 97 APPENDIX III— SPECIFICATIONS gypsum plaster has soaked for a few minutes it is mixed with the lime putty to a uniform paste ready for application. Application of Plaster Coatings — The scratch coat of plaster is applied lightly, but with sufficient pressure to embed the lath in the plaster and thoroughly cover the lath on the finish side. The surface of this coat is well scratched in both direc- tions to provide a bond for the brown coat. After the scratch coat has set firm and hard, but while it is still green, the spot grounds and the brown coat are ap- plied. The grounds are first attached to the surface of the scratch coat with a neat gypsum plaster. They are set to a line so that their outer faces are % in. out from the supports and so that they are in proper position back of the points where the standing finish is to be applied. A skin coat of plaster is then applied to the scratch coat and sufficient additional plaster immediately spread on to bring the brown coat out practically flush with the grounds. The surface is made straight and true with a rod and darby. After the brown coat has dried out, the finish coat is ap- plied. If the suction is too great, the brown coat is first sprin- kled with clean water with a clean brush. Enough material to cover the surface completely is first applied and worked thoroughly into the brown coat, using the material as thin as possible. This coating is allowed to draw for a few minutes to avoid blistering and enough material then applied to make the surfaces perfectly true. The surface is then gone over a third time with the material as thin as it can be handled and all imperfections worked out. After this coating has drawn for a few minutes, it is troweled to a smooth surface, applying water with a brush as necessary. The top and bottom of the walls are worked at the same time to avoid joining. During hot weather, the openings into the building are closed to prevent drafts of hot winds from drying out the plaster before it properly sets or crystalizes. If white or chalky spots appear they are sprinkled with clear water with a clean brush until the material sets up and hardens. The windows are then opened and a free circulation of air per- mitted after the plaster has set. During freezing weather, the building is heated to keep the plaster from freezing until it has set and become hard, after which a free circulation of air is permitted so that the plaster will dry out quickly. During damp or rainy weather, the building is heated to facilitate drying after the plaster has set and become hard. 98 METAL LATH AND PLASTER CONSTRUCTION After the plaster coatings have become thoroughly dry, the standing finish is attached by nailing through into the grounds, and the doors and sash mounted in position in the openings in the usual manner. Wood-Fibered Gypsum Plaster — Wood-fibered gypsum plas- ter is prepared and applied similar to sanded gypsum plaster, except that no sand or hair is used in the preparation of the finish. This finish is prepared ready for mixing with the de- sired quantity of water. APPENDIX IV CLAIMS MADE BY THE SUBMITTORS The Submittors set forth the following statemehts relative to this interior construction : PRINCIPLE OF DESIGN: Expanded metal lath is a fabric made from sheet metal so expanded as to form a support or vehicle on which plastic materials can be applied and held in place until set. There- after it provides a perfect, permanent mechanical key and re- inforces the plaster coat against cracking or falling. It ef- fectively holds the plaster in position after deterioration by fire so that the insulating value of the plaster is maintained long after it would otherwise have dropped ofif or become use- less. It is incombustible in itself and will not shrink, swell nor warp. It is cut from sheets of steel of standard known thickness, with a determined width of strand and fabricated by machine to a determined size of mesh. It is provided with a protective coating of sufficient durability to protect it from the weather before application. The wood studs or joists are manufactured at the saw mill into standard lengths and commercial sections. They are placed on end with the long axis of the section across the partition braced in the middle to reduce the length of the free column. Practically no shrinkage takes place in the direc- tion of the grain. The plastic material is prepared in such a manner that it may be mixed with sand and water at the job for ready ap- plication with a trowel. Fiber is added to the first coat to hold the keys in position until they set. The studs or joists are erected 12 in. or 16 in. on centers, lath stapled or nailed in position, and the plaster applied to form monolithic protective coating without disfiguring joints or the necessity of unsightly battens. No nails are exposed to view. FIRE STOPS: Fire stops at floor levels are provided by the use of a metal lath basket filled with incombustible materials and fully occu- pying the space between joists and studs to a height of 4 in. above floor level or other fire stops approved by the Building Code of the National Board of Fire Underwriters. -The brace between the studs midway between floor and ceiling also acts as a fire stop. PRACTICABILITY: The metal lath is easily cut, lapped and fitted and can read- ily be 'made to conform to plane or irregular surfaces. Expos- 100 FIRE RETARDANCE AND DURABILITY ure to weather or rough usage during shipment is of little con- sequence to the metal lath or lumber. The plastic material must be protected from moisture. The only tools needed for the application of metal lath are snips, pliers and a lather’s hatchet. Wood studs need only a saw and hammer and the plastic materials, a hoe, trowel and straight edge. The metal lath does not contribute to ruining of the dec- orations by staining nor by creating zones of different tempera- tures, the colder of which cause condensation on which dust settles. This combination of materials is entirely practical and per- mits the construction of very strong and light, bearing and non- bearing partitions. They are easily made straight and true. The metal lath demands a thick covering of plaster in three coats and does not lend itself to skimping, or amateur work- manship. It permits the application of plaster in sufficient thickness to form a practically sound-proof partition. The insulating material and the thickness of the plaster render the floor more sound proof than ordinary combinations. Wood joisted floor construction is the most universally used floor construction in America today. Its overwhelming per- centage of use proves it to be not only economical but familiar to all mechanics in the building trades. BEARING CAPACITY: The metal lath being tightly stapled or nailed to the wood supports gives them 'additional bracing in all directions in the plane of the partition and forms the diagonal members of a very deep and strong truss. This is effective even after the plaster has disintegrated. This truss may be very valuable in preventing the collapse of floors attached to or supported by it. The metal lath effectively prevents - the studs from buckling in the direction of their shortest axis and makes a wood. stud partition extremely rigid. Weights supported by individual studs may be transferred by the metal lath to other studs; consequently, the loss of con- siderable areas of plaster can be suffered without rendering the partition incapable of performing its structural function. Joisted construction for plastering is always designed with the maximum allowable bending as the criterion ; consequently there is always a strength greater than necessary for the mere support of the designed load, and the lower side of the joists can suffer severe charring and even burning before they become inadequate to carry the load. Even though sagging should take place, the expanded metal lath will conform to the sag 101 APPENDIX IV— SUBMITTORS’ CLAIMS and the plaster will not drop off, due to elongation in the lower fibres. No appreciable loss in load carrying capacity is experienced under fire conditions while the metal lath and plaster remains intact, and continues to insulate the wood from heat. The first appearance of disintegration is charring, which progresses at a slow rate. The penetration of fire at one locality or the loss of sec- tional area in several adjacent joists does not limit the bearing capacity of this floor system, nor immediately destroy its load bearing value. RETARDATION: The great virtue of this combination of materials in fire re- tardation is the ability of metal lath to lengthen the retarding value of any plastic coating that may be put upon it, by hold- ing the coating in place even after it has been reduced in strength by the action of heat, and so reinforcing it to prevent cracks from developing, thereby gaining the maximum insulat- ing value before any flame can pass. The metal lath and plaster provide no combustible material to add fuel to the fire within hollow spaces. The metal lath generates no gases or develops no other deleterious properties which may tend to break the bond or key and throw off the plaster coating. The three most common plastic coats, port- land cement, gypsum and lime, or combinations of them, are in- combustible and heat insulating. The wood studs are com- bustible, but being protected by the plastic coating from heat and fire, will maintain sufficient cross section to continue their function, as a bearing partition, safely for long periods and under all conditions of fire exposure likely to occur in premises for which this construction is advocated. FUNCTION AS FIRE BARRIER: Its function as a fire barrier is not measured solely by the period in which fire may destroy the exposed face, since the studs and other face must still be destroyed. In wood joist floor construction its function as a fire barrier is limited to its ability to carry the actual live load existing, and will thus retain its integrity as a fire barrier even after the joists themselves have been continuing to burn and until fire actually penetrates the upper flooring. DURABILITY: The metal lath resists all physical damage to the plaster by virtue of its reinforcement and being manufactured of steel it has great strength and durability. It is easy to repair by wir- 102 SAFE BEARING STRENGTH ing on additional material if the mesh is broken or by ap- plication of more plaster if the coating only is’ broken. It is not subject to progressive corrosion under ordinary condi- tions of habitable buildings. It is protected by its ov^n coat- ing and further protected by its encasement in any one of the common plastering materials. This partition resists vibration and cracking from sudden shocks, is vermin and rodent proof. It is one that cannot ordinarily be punctured by rough occu- pancy, but can be easily cut for alterations when desired. If desired, it can be patched in a sightly manner, mechanically right. ... This combination of materials forms a partition of great lateral strength, calling into play the resistance of the wood studs or joist as well as the metal lath and plaster. The par- tition also has a great resistance to being punctured by falling objects and absorbs impact of falling objects or concussion of explosions. It is resilient and not brittle and can be depended upon to resist successfully many conditions of fire hazard. If dislodged it does not break up into its constituent parts, but may fall intact as a blanket to retard fire even after it has lost its original position. ECONOMIES: The economy of this construction is improved by continuing popularity of thirty years. Numerous examples of this type of partition can be found with satisfactory service records for thirty years or more. STR^GTH AS BEARING PARTITIONS This combination of materials is entitled to recognition as an interior bearing partition or wall under any condition of safe loading for any wood. The following examples are sub- mitted : Live load assumed at 50 lbs. per sq. ft. Ceiling height, 11 ft. When 2 by 4 in. studs are used, 16 in. center to center, this partition will safely carry a structure consisting of two sup- ported floors, each with a span of 12 ft. on both sides of the partition, or the equivalent thereof. Additional load of 33 per- cent for 12 in. C. C. When 2 by 4 in. studs are used, 16 in. center to center, this partition will safely carry a . structure consisting of one floor, with two 20 ft. spans on each side of the partition, or the equiva- lent thereof. Additional load of 33 per cent for 12 in. C. C. When 2 by 4 in. studs are used, 12 in. center to center, this partition will safely carry a structure consisting of two sup- ported floors, each with a span of 16 ft. on both sides of the partition, or the equivalent thereof. 103 APPENDIX IV— SUBMITTORS’ CLAIMS When 2 by 6 in. studs are used, 16 in. center to center, this partition will safely carry a structure consisting of two sup- ported floors, each with a span of 20 ft. on both sides of the partition, or the equivalent thereof. Additional load of 33 per cent for 12 in. C. C.. When 2 by 6 in. studs are used, 16 in. center to center, this partition will safely carry a structure consisting of three sup- ported floors, each with a span of 18 ft. on both sides of the partition, or the equivalent thereof. Additional load of 33 per cent for 12 in. C. C. The above conditions of loading are all safe, in accordance with customary engineering design and practice, allowing an ample factor of safety. NON-BEARING PARTITIONS: This partition will effectively act as a non bearing fire bar- rier, with 2 by 2 in. or larger studs, under an}^ conditions of fire hazard for at least one hour. In buildings of so-called fire- proof construction, it may be used under any conditions in which a partition is required. SAFETY AFTER CHARRING: Calculations show that 79 per cent of the strength of the partition will still remain when the faces of all 2 by 4 in. studs are charred to an average depth of Yi in. A factor of safety of 3.6 will then remain. The charring on 2 by 4 in. studs may average a depth of 1 in. and even then retain 52 per cent of the strength of the partition, or a factor of safety 2.1. On the 2 by 6 in. studs, 77 per cent of the original strength of the partition will be retained after the charring has gone to a depth of 1 in. A factor of safety 3.08 will still remain. On account of the fact that wood joisted floors with plaster finish are designed with the maximum deflection of 1/360 of the span as the criterion, and as this produces a stronger floor than if the joists be designed for strength alone, there is an excess of stability which will permit of considerable charring or actual burning before failure occurs. EFFECT OF HOSE STREAMS: While there is sufficient fire retarding value in the plaster coat to permit the studs to retain ample strength against col- lapse for a considerable period without the aid of fire depart- ment or other fire quenching apparatus, it should be recog- 104 MINIMUM AND ALTERNATE SPECIFICATIONS nized that the assistance of such apparatus will reduce the length of exposure in buildings. Unless the fire department is present in such strength as to gain control of the fire, water could not be applied with suf- ficient force to throw off sections of plaster large enough to expose bearing members to complete collapse. This is due in partitions to the truss action set up if several studs are com- pletely burned through, transferring the loads to all other studs, and in floor construction, to the fact that the floor is bridged frequently and that the double flooring acts as a fire retardant and is strong enough to span over four or five joists, should they completely disappear. IU5 APPENDIX V UNDERWRITERS’ LABORATORIES’ STANDARD EQUIPMENT AND PANELS FOR TESTS OF IN- TERIOR WALL, AND PARTITION FINISH ON WOOD SUPPORTS. GENERAL CHARACTER: The equipment for the tests of partitions consists of the apparatus used for the Fire and Stream Tests and the apparatus for the tests of materials. The standard test panels consist of at least one panel of standard size for each of the tests, made of the materials under investigation and seasoned until in normal condition. The equipment, with the exception of some of the apparatus used in the tests of materials, is located in a building of fire resistive construction specially designed for work of this char- acter and known as building No. 3. The building is heated during cold weather and the tests are not unduly subject to out- side weather influences. FIRE AND HOSE STREAM TESTS The equipment used in these tests consists of the apparatus for handling the test panels, the furnace in which the test panels are subjected to fire, the apparatus for measuring the tempera- tures in the furnace and the transmission of heat through the panels, the apparatus- for measuring the deflections of the panels, the gauge for measuring the fire pressures in the furnace, and the hydrant and nozzle by means of which the stream of water is applied in the Fire Stream Tests. The equipment is located in the first story of the building. STANDARD TEST PANELS: The standard test panels are 10 ft. wide and 11 ft. high, and consist of a standard frame of wood studs covered on one or both sides with the materials under investigation, installed as nearly as possible in the manner advocated by the *Submittor. The panels are mounted in the openings in the movable walls forming the front of the test furnace. The standard frame consists of eight 2 by 4-in.‘ yellow pine studs spaced on 16-in. centers except at the sides where they are spaced 4 in. so as to completely fill the 10-ft. wall opening. The studs are nailed to single 2 by 4-in. yellow pine plates and sills extending across the top and bottom, respectively. The side studs are nailed to wooden inserts set in the side walls at 24-in. intervals, and the frame is made tight against the masonry at all points with mortar. 106 EQUIPMENT EOR WALL TESTS APPARATUS FOR HANDLING TEST PANELS: This apparatus consists of the movable walls in which the test panels are mounted, a system of overhead step beams from which the movable walls are suspended, a traveling crane by which the movable walls are transferred to various ceiling beams, the trolleys by which the movable walls are conveyed along the ceiling beams to the traveling crane and into the test furnace, and an electric hoist by which the movable walls are drawn from the furnace at the end of the fire tests. The movable walls consist of heavy steel sections assembled in the form of rectangles and the masonry necessary to protect the steel from heat during the tests and provide openings for the standard test panels. The rectangular steel frames are designed to carry all loads and resist the expansion in the test panels during the periods they are exposed to fire. Each mov- able wall is provided with two trolleys attached to the steel work at the top. The overhead beams are attached to the ceiling on each side of the middle bay in which the traveling crane moves. One end of each beam registers with a similar beam at the bottom of the traveling crane. The overhead beams provide for the handling and storage of fifteen movable walls in addition to one in front of the furnace and one for the installation of a new test panel. The traveling crane is specially designed to handle the mov- able walls in which the test panels are mounted. It is operated from the oor by a hand chain and serves to transfer the movable walls between the storage beams and the test furnace. The trolleys are securely but loosely attached to the top of the movable walls and travel on the lower flanges of the over- head beams. They are operated from the floor by hand chains and serve to support the movable walls and convey them to and from the traveling crane and into position in front of the test furnace. The hoist has a capacity of four tons, is provided with two drums and is electrically driven. It is used to draw the remov- able walls carrying the test panels from the furnace at the end of the fire tests, a steel cable being attached to the steel frame of the wall. The hoist is located at one side of the test furnace on the second story of the building. STANDARD TEST FURNACE: The furnace employed in the tests of partition panels is known as furnace No. 2. The furnace proper consists of a shallow combustion chamber approximately 12 ft. wide, 14^ ft. high and 16 in. deep, communicating at the bottom with a pit 107 APPENDIX V— UNDERWRITERS’ LABORATORIES about 3 ft. in depth. The combustion chamber is enclosed by a solid brick wall at the back and one end, and by movable brick walls in steel frames at the front and the other end. The mov- able walls are suspended from overhead steel beams by trolleys, the wall forming the front of the furnace being provided with an opening of the size of the panel to be tested. The top of the furnace consists of heavy fire clay blocks containing six vents leading to a stack. The vents are provided with dampers made of fire-resisting material. Each end wall of the furnace is pro- vided with four observation holes glazed with mica and so arranged that all parts of the interior of the combustion chamber and the exposed face of the test panel may be observed. Obser- vation galleries outside of the furnace afford access to the upper observation holes. The furnace is heated by means of six 4-in. blast burners mounted in the back wall of the furnace at the bottom of the combustion chamber. The burners are supplied with gas and air through mixing tubes which enter the furnace at the back. Additional air is supplied directly to the combustion chamber through fifty secondary air inlets uniformly spaced over the back wall of the chamber. The flow of gas and air to each burner and to each secondary air inlet is regulated by individual valves provided with graduated scales so that the valve settings may be duplicated accurately. Gas is supplied to the furnace through a 6-inch pipe connected directly to the street mains. Air is supplied to the burners and to the secondary air inlets by a blower driven by an electric motor. The entire gas and air supplies are each controlled by valves in the main connections. The apparatus for measuring the temperatures within the furnace consists of five thermo-couples symmetrically 'distributed over the exposed surface of the test panel, the instruments for indicating the temperatures, and a switchboard and connections for placing any of the thermo-couples in circuit with the instru- ments. The thermo-couples are inserted through openings in the back wall of the furnace and located 6 in. from the face of the test panel. The connections are such that the position of the couples can be maintained in case of deflections in the test panel. Mercury thermometers are suspended near the cold junctions of the thermo-couples for use in ascertaining the corrections to be made in the temperature readings. APPARATUS FOR TEMPERATURE MEASURE- MENTS: The apparatus for measuring the temperatures on the unex- posed face of the test panel consists of five mercury thermom- 108 EQUIPMENT FOR WALL TESTS eters symmetrically distributed over the surface of the test panel opposite the thermo-couples in the furnace. The bulbs are in contact with the surfaces of the test panel and are protected from outside influences by uniform plaster of Paris shields cemented to the surface of the test panel. The temperatures are read directly or by a telescope mounted at a convenient distance back of and opposite the middle of the test panel. APPARATUS FOR DEFLECTION MEASUREMENTS: The apparatus for measuring deflections on the unexposed face of the test panels during the fire tests consists of three wires stretched horizontally across the face of the panel and firmly attached to the channels. The wires are symmetrically spaced, one being at the middle and' one half way between on either side of the middle wire. The position of the sample with respect to the wires is noted at the middle of the top and bottom wires and at three points on the middle wire, the points being symmetrically located from the middle of the panel and occu- pying the same relative position in each case. The readings are taken from a platform 'constructed in front of the panel with a rule graduated to 1/16 inch. APPARATUS FOR FURNACE PRESSURE MEAS- UREMENTS: The apparatus for measuring the fire pressures within the furnace consists of a differential draft gauge connected to the combustion chamber by piping. The gauge is provided with a scale reading in 1/100 in. water column. APPARATUS FOR APPLYING HOSE STREAMS: The apparatus used in the hose Stream Tests consists of a specigil hydrant at the back of and to one side of the test furnace, a flexible play pipe and nozzle attached to the hydrant, a gate valve for controlling the stream, and a pressure gauge at the base of the nozzle. The tip of the nozzle is located 20 ft. from the test panel when it is pulled out from the test furnace. The hydrant is connected to a water main in a trench under the floor and is supplied by three 4,500-gal. pressure tanks, or by an electrically-driven fire pump having a capacity of 500 gal. per min. located in another building. 109 APPENDIX VI UNDERWRITERS’ LABORATORIES’ STANDARD EQUIPMENT FOR TESTS OF FLOOR AND CEILING CONSTRUCTION. GENERAL CHARACTER: The equipment for the tests of floors and ceilings consists of the apparatus used for the Fire and Fire and Hose Stream Tests. The standard test panels consist of at least one panel of stand- ard size for each of the tests, made of the materials under inves- tigation and seasoned until in normal condition. The equipment with the exception of some of the apparatus used in the tests of materials, is located in a buildijig specially designed for work of this character and known as West Floor Furnace. FIRE AND HOSE STREAM TESTS The equipment used in these tests consists of the furnace in which the test panels are subjected to fire, the apparatus for measuring the temperatures in the furnace, and the sample, the transmission of heat through the panels, the apparatus for measuring the deflections of the panels, the gauge for measuring the fire pressures in the furnace, and the hydrant and nozzle by means of which the stream of water is applied in the Fire and Hose Stream Tests. STANDARD TEST PANELS: The standard test panels are 13 ft. 7 in. wide and 17 ft. 11 in. long in which the materials under investigation are installed as nearly as possible in the manner advocated by the submitter. The panels are mounted in the restraining frame of the test furnace. STANDARD TEST FURNACE: The furnace proper consists of a shallow combustion cham- ber approximately 12 ft. wide and 16 ft. long and 38 in. deep. The combustion chamber is enclosed by a solid brick wall along each end and by two removable gypsum walls at each side. The removable walls are suspended on a steel beam. Each end of the furnace is provided with two vents leading to two stacks. Each end wall of the furnace is provided with three observation holes and each removable gypsum wall with two observation holes glazed with mica and so arranged that all parts of the interior of the combustion chamber and exposed face of the test panel may be observed. no EQUIPMENT FOR FLOOR TESTS The furnace is heated by means of 39 blast burners ^mounted in the floor of the furnace chamber. The burners are supplied with gas and air through mixing tubes. The flow of gas and air to each burner is regulated by indi- vidual valves provided with graduated scales so that the valve settings may be duplicated accurately. The gas is supplied to the furnace through a 6 in. pipe con- nected directly to the street mains throu'gh a meter. Air is supplied to the burners by a blower driven by an electric motor. The entire gas and air supplies are controlled by valves in the main connections. APPARATUS FOR TEMPERATURE MEASURE- MENTS: The apparatus for measuring the temperatures within the furnace consists of six thermo-couples symmetrically distributed under the exposed surface of the test sample, the instruments for indicating temperatures, and a switchboard and connections for placing the thermo-couples in circuit with the instruments. The thermo-couples are inserted through openings in the brick floor of the furnace and located 6 in. from the face of the test sample. Provision is also made for measuring temperatures in the sample. APPARATUS FOR DEFLECTION MEASUREMENTS: The apparatus for measuring deflections on the unexposed face of the test panel during the test consists of vertical targets symmetrically distributed over the unexposed face of the test sample and a surveyors level located at one side of the sample. The targets are about 36 in. in length provided with a scale graduated to 1/10 of an inch and project at right angles to the unexposed surface of the test sample to which they are rigidly attached. The surveyors level is located at a convenient- dis- tance from the panel so that all scales in the targets are within the range of the telescope ; it is lined up so that the telescope reads about 2 in. above the bottom of the scale on the targets. APPARATUS FOR FURNACE PRESSURE MEAS- UREMENTS: The apparatus for measuring the fire pressures within the furnace consists of a differential draft gauge connected to the combustion chamber by piping. The gauge is provided with a scale reading 1/100-in. water column. _ 111 APPENDIX VI— UNDERWRITERS’ LABORATORIES APPARATUS FOR APPLYING FIRE STREAMS: The apparatus used in the Fire Stream Tests consists of a special hydrant at the back of and to one side of the test furnace, a flexible play pipe and nozzle attached to the hydrant, a gate valve for controlling the stream, and a pressure gauge at the hydrant. The tip of the nozzle is located 12 ft. from the test panel. The hydrant is connected to a water main and is supplied by three 4,500-gal. pressure tanks, or by an electrically-driven Are pump having a capacity of 500 gal. per min. located in another building. ) APPENDIX VII STANDARD SPECIFICATIONS for FIRE TESTS OF MATERIALS AND CONSTRUCTION CONTROL OF FIRE TESTS 1. The conduct of fire tests of materials and construction shall be controlled by the standard time-temperature control curve shown in Fig. A. The points on the curve which deter- mine its character are: 1,000° F. at 5 minutes 1,300° F. at 10 minutes 1,550° F. at 30 minutes 1,700° F. at 1 hour 1,850° F. at 2 hours 2,000° F. at 4 hours 2,300° F. at 8 hours TIME TEMPERATURE CURVES UNDERWRITERS’ LABORATORIES 113 APPENDIX VII— TEST SPECIFICATIONS 2. (a) The temperature fixed by the curve shall be deemed to be the average true temperature of the furnace gases as obtained from the readings of several thermo-couples (not less than three) symmetrically disposed and distributed in such a manner as to show the temperatures of the gases near all parts of the sample. (b) The temperatures shall be read at intervals not exceeding 5 min. during the first hour, and thereafter the intervals may be increased to not more than 15 min. CLASSIFICATION AS DETERMINED BY TEST 3. (a) Fire-resistive materials and construction shall be classified in accordance with the degree of protection they af¥ord when measured by a fire test conducted in conformity with the standard time-temperature control curve as : 4-hour Protection 2-hour Protection 1-hour Protection ^-hour Protection ^-hour Protection (b) Other classes may be interpolated or added as needed. TEST STRUCTURES 4. (a) The test structure may be located at any place where all the necessary facilities for properly conducting the test are provided. (b) Entire freedom is left to each investigator in the design of his test structure and the nature and use of fuel, provided the test requirements are met. TEST SAMPLES 5. The material or construction constituting the test sample shall be truly representative of the regular practice. CONDUCT OF FIRE TESTS 6. The fire test on the sample with its applied load, if any, shall be continued until failure occurs, or until it has withstood the test conditions for a period equal to times that for wnich classification is desired. 7. A second test with duplicate sample shall be made to determine the effect of a hose stream on a sample under fire test, the water being applied at the end of a period equal to three-fourths of that for which classification is desired, but not later than one hour after the beginning of the test; except that for classification periods of one-half hour or less the fire stream test may be omitted. 8. The size of nozzle, water pressure and time of water 114 FIRE TESTS application shall be as indicated in Table I. The hose stream shall be first directed at the middle of the sample and then at all parts of the exposed faces, changes in direction being made slowly. 9. For any material or construction intended to carry load other than its own weight, the full rated safe working load shall be applied during the entire fire test, also during the fire stream test. After completion of the fire stream test, the sample shall be subjected to excess loading as prescribed under specifications for the different structural parts. FLOOR AND ROOF TESTS 10. For floor and roof tests the sample shall be of such a size that the minimum span of the supporting beams of the floor arch shall be 12 ft., and the supporting beams and girders shall have a clearance of at least 8 in. from the walls of the test structure. 11. The floor or roof may be tested as soon after construc- tion as desired, but within 40 days. Artificial drying will be allowed if desired. 12. If the construction is to be plastered in practice, the sample shall be plastered in the same manner. 13. The floor or roof shall be loaded in a manner to develop in each member of the construction stresses equal to the maxi- mum safe working stress allowed in the material of the member. 14. The test shall not be regarded as successful unless the following conditions are met: (a) The floor or roof shall have sustained safely the full rated safe working load during the fire test without passage of flame, for a period equal to lj4 times that for which classification is desired. (b) The floor or roof shall have sustained safely the full rated safe working load during the fire stream test as prescribed in Sections 7 and 8, without passage of flame, and after its com- pletion shall sustain a total load equal to the dead load plus 2^/2 times the live load for which the construction is designed. NON-BEARING PARTITION TESTS 15. For partition tests the area of the sample shall be not less than 100 sq. ft. and no dimension less than 9 ft. 16. Temperatures on the outer surface of the partition shall be read by not less than five thermometers, symmetrically dis- posed and placed against the surface of the partition with their bulbs properly protected against radiation of heat. 17. The distance of the nozzle from the partition during the application of water shall be not more than 20 ft. when the hose stream is applied approximately normal to the surface of the 115 FIRE TESTS partition, which distance shall be reduced by 1 ft. for each deviation of 10 deg. of angle from the normal when the hose stream is applied at an angle to the surface of the partition. 18. The test shall not be regarded as successful unless the following conditions are met: (a) The partition shall have withstood safely the fire test for a period equal to 1^ times that for which classification is desired. (b) The partition shall have withstood the fire stream test as prescribed in Sections 7 and 8. (c) No flame shall have passed through the partition during the prescribed fire period. (d) Transmission of heat through the partition during the prescribed fire period shall not have been such as to raise the temperature on its outer surface in excess of 300° F. (e) The partition shall not have warped or bulged or disinte- grated, under the action of fire or water to such an extent as to be unsafe. TABLE I Size of Water Time of Parts of Structure Type of Protection Hose Nozzle Pressure Appli- Nozzle cation In. Lb. Min. 4-hour 50 10 2-hour IVs 50 5 Floor and Roofs i 1-hour m 50 2.5 ^-hour 1/8 30 1 ' ^-hour 1/8 , 15 1 4-hour 1/ 50 5 Walls, Columns and ,2-hour 1-hour 1/ 1/ 1/8 30 3 30 2.5 Partitions y^-houv 30 1 34-hour 1/8 15 1 116 SECTION V RECOMMENDATIONS TO THE FIRE COUNCIL OF UNDERWRITERS’ LABORATORIES: We recommend promulgation of the following notices to subscrib- ers and the action indicated thereby; Guide No. 40 UC. 16. 3 (Corridor Partitions) August 10, 1922. 40 UC. 16.18 (Room Partitions) Lab. File R. 1355. 40 UC. 16.22 (Vertical Communications) Associated Metal Lath Manufacturers, Chicago, 111. National Lumber Manufacturers Association, Chicago, 111.. Washington, D. C. Metal Lath and Gypsum Plaster on Wood Studs: Interior Bearing, Corridor, and Room Partitions and Walls and Vertical Shaft Enclosures. ^ Submitters Bearing partitions, walls or enclosures of wood studs, 2 by 4 in. or larger, spaced 16 in. centers effectively fire stopped, finished on each side with in. diamond mesh expanded metal lath, cut from not less than No. 26 U. S. gauge steel, and weighing not less than 2.5 lbs. per sq. yd. attached to supports by not less than 1^ in., 4 penny nails or in., 14 gauge wire staples spaced not to exceed 6 in. on center; and ^ in. three-coat wood fibered or sanded gyp- sum plaster. Metal lath lapped at all joints with walls, ceilings or other partitions; wood or metal trim and standing finish se- cured to spot grounds. Intended for use on the inside of buildings of frame or ordinary con- struction with live loads carried by this construction up to 50 lbs. per sq. ft. and when permitted by local rules. Inspection departments having jurisdiction to be consulted before in- stallation. CLASSIFICATION Rlhr. Listed — Fire. REEXAMINATION SERVICE. 117 RECOMMENDATIONS Guide No. 40 UC. 16. 3 (Corridor Partitions) August 10, 1922. 40 UC. 16.18 (Room Partitions) Lab. File R. 1355. 40 UC. 16.22 (Vertical Communications) Associated Metal Lath Manufacturers, Chicago, 111. National Lumber Manufacturers Association, Chicago, 111. Washington, D. C. \ Metal Lath and Gypsum Plaster on Wood Studs: Interior Non- Bearing Corridor, and Room Partitions and Walls Vertical Shaft Enclosures. Submittors Non-bearing partitions, walls, or enclosures of wood studs, 2 by 2 in., 2 by 4 in. or larger, spaced 16 in. centers; effectively fire stopped and finished on each side with ^ in. diamond mesh expanded metal lath cut from not less than No. 26 U. S. gauge steel, weighing not less than 2.5 lbs. per sq. yd. attached to supports by not less than in., 4 penny nails or in., 14 gauge wire staples spaced not to exceed 6 in. on center; and ^ in. three-coat wood fibered or sanded^ gypsum plaster. Metal lath lapped at all joints with walls and ceilings or partitions, wood or metal trim and standing finish secured to spot grounds. Intended for the sub-division of floor areas in buildings of frame or ordinary construction and in buildings of superior constructon in which partitions having combustible supports are allowed. Inspection departments having jurisdiction to be consulted before in- stallation. CLASSIFICATION Rlhr. Listed — Fire. REEXAMINATION SERVICE. 118 RECOMMENDATIONS Guide No. 40 UC 9 August 10, 1922 — Laboratories’ File R. 1355. Associated Metal Lath Manufacturers, Chicago, 111. National Lumber Manufacturers Association, Chicago, 111. Washington, D. C. Metal Lath and Gypsum Plaster on Wood Supports: 'Interior, Single, Wall, Partition and Ceiling Finish. Interior finish of the built-up type, consisting of ^ in. diamond mesh expanded metal lath cut from not less than No. 26 U. S. gauge steel, weighing not less than 2.5 lbs. per sq. yd. for walls and par- titions and not less than No. 25 U. S. gauge steel weighing not less than 3 lbs. per sq. yd. for ceilings, attached to joists by not less than 2 in., 6 penny nails spaced not to exceed 6 in. on center, or by equivalent staples, or to studs by not less than lJ /2 in. 4 penny nails or 1^ in., 14 gauge wire staples spaced not to exceed 6 in. on center; and in. three-coat wood fibered or sanded gyp- sum plaster. Intended for use on walls, ceilings, and partitions on the interior of buildings of frame or ordinary construction. Inspection departments having jurisdiction to be consulted before in- stallation. CLASSIFICATION: Single finish on walls, partitions, and ceiliners R30m (rating applies only when exposed from the finished face). Listed — Fire. Submitters REEXAMINATION SERVICE. Guide No. 40 UC 6 August 10, 1922 — Laboratories’ File R. 1355. Combustible Floors The great value in safeguarding life and property of floors as fire stops, preventing the vertical spread of fire within buildings makes it essential that all floors be of materials, design and construction developing a high degree of fire resistance, and with partitions of a similar resistance, fire can frequently be confined to the room of origin. Floors should have a minimum number of vertical open- ings and^ these should be protected by standard retardants of a rating suitable for the exposure. The “R” (fire retardant) ratings for floor constructions given in the following cards are based upon the performance of these construc- tions under the Standard Fire Endurance and Fire and Hose Stream Tests which are judged equivalent to severe fire exposure conditions. Only floors rated not lower than the probable fire exposure should be used. Inspection authorities having jurisdiction should be consulted in all cases. , 119