250 ROOF COVERINGS 



When roofing slates are laid on sheathing they are fastened by 

 two nails, one in each upper corner. When supported directly on sub- 

 purlins the slates are fastened by copper or composition wire. Gal- 

 vanized and tinned steel nails, copper, composition and zinc slate roofing 

 nails are used. Where the roof is to be exposed to corrosive gases cop- 

 per, composition or zinc nails should be used. 



Slate roofs when made from first class slates well laid have been 

 known to last 50 years. When poorly put on or when an inferior qual- 

 ity of slate is used slate roofs are comparatively short-lived. Slates are 

 easily broken by walking over the roof and are sometimes broken by 

 hailstones. Slate roofing is fireproof as far "as sparks are concerned, 

 but the slates will crack and disintegrate when exposed to heat. Local 

 conditions have much to do with the life of slate roofs ; an ordinary life 

 being from 25 to 30 years. 



First class slate 3-16 to ^4 inches thick may ordinarily be obtained 

 f . o. b. at the quarry for from $5 . oo to $7 . oo per square ; common 

 slate for from $2.00 to $4.00 per square; while extra fine slate may 

 cost from $10.00 to $12.00 per square. 



An experienced roofer can lay from i l /2 to 2 squares of slate in a 

 day of 10 hours. In 1903 slater's supplies were quoted as follows: 

 Galvanized iron nails, 2^/2 to 3 cents per Ib. ; copper nails, 20 cents per 

 Ib. ; zinc nails, 10 cents per Ib. ; slater's felt, 70 to 75 cents per roll of 

 500 square feet; two-ply tar roofing felt, 75 cents per square; slater's 

 cement in lo-lb. kegs, 10 cents per Ib. 



Trautwine gives the cost of slate roofs as $7.00 per square and 

 upwards. The costs of slate roofs per square is given in the reports of 

 the Association of Railway Superintendents of Bridges and Buildings, 

 as follows: New England, $9.00 to $12.00; New York, $9.00 to 

 $10.00; Virginia $4.10 to $5.00; California, $10.00 to $10.50. 



Tile Roofing. Baked clay or terra-cotta roofing tiles are made 

 in many forms and sizes. Plain roofing tiles are usually 10^2 inches 

 long, 6^4 inches wide and ^ inches thick ; we*igh from 2 to 2^2 pounds 

 each and lay one-half to the weather. There are many other forms of 



