SPECIFICATIONS 



393 



P = capacity of truss in pounds per square foot of hor- 

 izontal projection; 



L = span of the truss in feet; 



A = distance between trusses in feet. 



14. Weight of Covering. The weight of corrugated Corru K ated 

 steel shall be taken from Table I. 



TABLE I. 



WEIGHT OF FLAT, AND CORRUGATED STEEL SHEETS WITH 

 2^ -INCH CORRUGATIONS 



When two corrugations side lap and six inches end lap 

 are used add 25 per cent to the above weights ; when one cor- 

 rugation side lap and four inches end lap are used add 15 per 

 cent to the above weights to obtain weight of corrugated steel 

 laid. For paint add 2 pounds per square. The weight of cov- 

 ering shall be reduced to weight per square foot of horizontal 

 projection before combining with weight of trusses. 



15. Slate laid with 3-inch lap shall be taken at a weight 

 of 7^/2 pounds per square foot of inclined roof surface for 3-16" 

 slate 6" x 12", and 6 l / 2 pounds per square foot of inclined roof 

 surface for 3-16" slate 12" x 24", and proportionately for other 

 sizes. 



1 6. Terra-cotta tile roofing weighs about 6 pounds per 

 square foot for tile I inch thick; the actual weight of tile and 

 other roof coverings not named shall be used. 



17. Sheathing of dry pine lumber shall be assumed to 

 weigh 3 pounds per foot and dry oak purlins 4 pounds per 

 foot board measure. 



1 8. The exact weight of sheathing, purlins, bracing, ven- 

 tilators, cranes, etc., shall be calculated. 



Steel. 



Slate. 



Tile. 



Sheathing 

 and Purlina. 



Miscellaneous 

 Loads. 



