SPECIFICATIONS. 59 



COVERING. 



47. Corrugated Steel.-yCorrugated steel shall generally have 2$ in. corrugations when used 

 for roof and sides of buildings, and li in. corrugations when used for lining buildings. The 

 minimum gage of corrugated steel shall be No. 22 for roofs, No. 24 for sides, and No. 26 for lining. 



The gage of corrugated steel in U. S. standard gage and weight per sq. ft. shall be shown 

 on the general plan. 



48. Spacing Purlins and Girts. The span, or center to center distance of purlins, shall not 

 rxrivd the distance given in Fig. 18 for a safe load of 30 Ib. per sq. ft. Corrugated steel sheets 

 shall preferably span two purlin spaces. Girts shall be spaced for a safe load of 25 Ib. per sq. ft. 

 in Fig. 1 8. 



49. End and Side Laps. Corrugated steel shall be laid with two corrugations side lap and 

 six inches end lap when used for roofing, and one corrugation side lap and four inches end lap 

 when used for siding. 



50. Fastening. Corrugated steel shall be fastened to the purlins and girts by means of 

 galvanized iron straps J in. wide by No. 1 8 gage, spaced 8 to 12 in. apart; by clinch nails spaced 

 8 to 12 in. apart; or by nailing directly to spiking strips with 8d barbed nails, spaced 8 in. apart. 

 Spiking strips shall preferably be used with anti-condensation lining. Bolts, nails and rivets 

 shall always pass through the top of corrugations. Side laps shall be riveted with copper or 

 galvanized iron rivets 8 to 12 in. apart on the roof and I J to 2 ft. apart on the sides. 



51. Corrugated Steel Lining. Corrugated steel lining on the sides shall be laid with one 

 corrugation side lap and four in. end lap. Girts for corrugated steel lining shall be spaced for a 

 safe load of 25 Ib. per sq. ft. as given in Fig. 18. 



52. Anti-condensation Lining. Anti-condensation roof lining shall be used to prevent 

 dripping in engine houses and similar buildings, and shall be constructed as follows: Galvanized 

 wire poultry netting is fastened to one eave purlin and is passed over the ridge, stretched tight 

 and fastened to the other eave purlin. The edges of the wire are woven together and the netting 

 is fastened to the spiking strips, where used, by means of small staples. On the netting are laid 

 two layers of asbestos paper ^ in. thick and two layers of tar paper. The corrugated steel is 

 then fastened to the purlins in the usual way; ^ in. stove bolts with I in. X i in. plate washers 

 on the lower side are used for fastening the side laps together and for supporting the lining; or 

 the purlins may be spaced one-half the usual distance where anti-condensation lining is used and 

 the stove bolts omitted. 



53. Flashing. Valleys or corners around stacks shall have flashing extending at least 12 in. 

 above where water will stand, and shall be riveted or soldered, if necessary, to prevent leakage. 



4 Flashing shall be provided above doors and windows. 



'54. Ridge Roll. All ridges shall have a ridge roll securely fastened to the corrugated steel. 



55. Corner Finish. All corners shall be covered with standard corner finish securely fastened 

 to the corrugated steel. 



56. Cornice. At the gable ends the corrugated steel on the roof shall be securely fastened to a 

 finish angle or channel connected to the end of the purlins, or, where molded cornices are used, 

 to a piece of timber fastened to the ends of the purlins. 



57. Gutters. Gutters and conductors shall be furnished at least equal to the requirements 

 of the following table: 



Span of Roof. Gutter. Conductor. 



Up to 50 ft. 6 in. 4 in. every 40 ft. 



50 ft. to 70 ft. 7 in. 5 in. every 40 ft. 



70 ft. to 100 ft. 8 in. 5 in. every 40 ft. 



Gutters shall have a slope of at least i in. in 15 ft. Gutters and conductors shall be made 

 of galvanized steel not lighter than No. 24. 



58. Ventilators. Ventilators shall be provided and located so as to properly ventilate the 

 building. They shall have a net opening for each 100 sq. ft. of floor space as follows: not less 

 than one-fourth sq. ft. for clean machine shops and similar buildings; not less than one sq. ft. 

 for dirty machine shops; not less than four sq. ft. for mills; and not less than six sq. ft. for forge 

 shops, foundries and smelters. 



59. Shutters and Louvres. Openings in ventilators shall be provided with shutters, sash, 

 or louvres, or may be left open as specified. 



Shutters must be provided with a satisfactory device for opening and closing. 



Louvres must be designed to prevent the blowing in of rain and snow, and must be made 

 stiff so that no appreciable sagging will occur. They shall be made of not less than No. 20 gage 

 galvanized steel for flat louvres, and No. 24 gage galvanized steel for corrugated louvres. 



60. Circular Ventilators. Circular ventilators, when used, must be designed so as to prevent 

 down drafts. Net opening only shall be used in calculations. 



