2 6o ROOF COVERINGS 



and afterwards coated with a hard solution of the same material, there- 

 by making the roofing at once light in weight as well as strong, dur- 

 able and elastic. It is thoroughly acid and alkali proof, is not affected 

 by coal gas or smoke and can be laid on either pitched or flat roofs, 

 proving equally effectual in both cases. Inasmuch as it contains no tar 

 or asphalt the roofing is not affected by extremes in temperature." 



Ruberoid is made }^-ply weighing 22 pounds per square; i-ply 

 weighing 30 pounds per square; 2-ply weighing 43 pounds per square; 

 and 3-ply weighing 51 pounds per square. The 2-ply and the 3~ply 

 roofing are commonly used for factories and mills. The roofing is put 

 up in rolls 36 inches wide, containing two squares (200 square feet), 

 with an additional allowance of 16 square feet for two-inch laps at the 

 seams ; sufficient tacks, tin caps and cement are included with each roll. 



Ruberoid roofing costs from $2.75 to $3-75 per square laid on the 

 roof. 



Ferroinclave. This is a patented roofing made by the Brown 

 Hoisting Machinery Co., Cleveland, Ohio, and is described in a letter 

 to the author as follows: "Ferroinclave roofing is made by coating a 

 special crimped or corrugated iron or steel on both sides with a mixture 

 of Portland cement and sand, after which it is painted on the upper 

 side. The sheets are made of No. 22 or No. 24 sheet steel, and full 

 sized sheets are 20 inches wide and 10 feet long. The steel is crimped 

 or corrugated with corrugations about 2 inches wide and J^ inch deep, 

 the width of the corrugation on the outer side being less than on the 

 inner side, thus forming a key to hold the cement mortar in place. The 

 sheets are laid in the same manner as corrugated steel, and a coating 

 of Portland cement mortar, composed of I part Portland cement and 

 2 parts sand, is plastered on the upper and lower surfaces to a thick- 

 ness of y% of an inch above and below the corrugations, making the 

 total thickness of the roofing ij4 inches. The weight of No. 24 sheet 

 steel Ferroinclave is about 15 Ibs. per square foot when filled with cem- 

 ent mortar as above. A test of a sheet of Ferroinclave made as above, 

 showed failure with a uniformly distributed load of 300 Ibs. per square 

 foot with supports 4' 10" apart, the cement having set ten days. The 



