36 MANAGEMENT OF DAIRY PLANTS 



Engine and Boiler Foundations. These should be built in 

 accordance with details and specifications furnished by the man- 

 ufacturer, and should be made from concrete composed of one 

 part Portland cement, two and one-half parts clean sand, and 

 five parts coarse gravel, broken stone, or tile. The foundation 

 bolts should be placed in gas piping ^ inch greater in diameter, 

 and should extend to within 3 inches of the bottom of the 

 foundation. 



ROOFS 



The size and number of timbers required to support the roof 

 should be carefully figured by an architect. It is considered 

 that timbers should not span over more than 24 feet. If the 

 building is of such construction that longer timbers are required, 

 it may be advisable to use one or more steel beams, thereby 

 shortening the timbers required as well as increasing the strength 

 of the building. 



There are two general types of roofs the flat and the 

 pitched. 



Flat Roof. The flat roof is constructed in much the same 

 manner as a floor except that it has a slight pitch. The most 

 common materials used on this type of roof are gravel, tin, and 

 special prepared roofing such as asbestos, etc. 



1. Gravel Roof. The gravel roof should have a pitch of from 

 5/8 inch to i inch in the foot. It is supposed to protect a wooden 

 roof better than tin, its life being from 10 to 15 years. Its cost 

 will amount to about $7 per square, 1 a square being 100 square 

 feet. 



2. Tin Roof. A tin roof, if properly laid and kept painted, 

 will last from 20 to 30 years. Its cost will vary from $8 to $11 

 per square. 1 



3. Prepared Roofing. Such roofs are constructed in accord- 

 ance with specifications furnished by the manufacturer. The 

 cost of constructing a four-ply asbestos roof at Hartley, Iowa, 

 was $7.29 per square. 2 



1 Figured at pre-war cost of material and labor, 



2 Bui. 139, la. Agr. Expt. Sta., 1913, 



