282 FLOORS 



Earth and cinder floors are very cheap and are adapted to forge 

 shops and many other places where concrete and brick floors are now 

 put down. Floors of this class should be well tamped in layers and 

 should be carefully drained. Tar-concrete and asphalt floors are more 

 elastic and conduct less heat than any of the floors above mentioned, but 

 the surface is not sufficiently stable to support machinery directly, and 

 floors of this class are very much improved by the addition of a contin- 

 uous wooden wearing surface. 



(3) Floors of wood or with a wooden wearing surface appear to 

 be the most desirable for shops, mills and factories. Wooden floors are 

 elastic, non-heat conducting and are pleasant to work on. They are 

 cheap, easily laid, repaired and renewed. They are easily kept clean and 

 do not give rise to grit and dust. 



The most satisfactory wearing surface on a wooden floor is rock 

 maple % to ij^ inches thick and 2^2 to 4 inches wide, matched or not 

 as desired. The matched flooring makes a somewhat smoother floor and 

 is on the whole the most satisfactory. The wearing floor should be 

 laid to break joints and should be nailed to planking or stringers laid 

 at right angles to the surface layer. The thickness of the planking will 

 depend upon the foundation and upon the use to which the floor is to 

 be put. 



The different classes of floors will now be briefly discussed and illus- 

 trated by examples of floors in use. 



Cement Floors. The construction of cement or concrete floors is 

 similar to the construction of cement sidewalks, the only difference 

 being that the floor usually requires the better foundation. The foun- 

 dation will depend upon the use to which the floor is to be put, and upon 

 the character of the material upon which the foundation is to rest. The 

 excavation should be made to solid ground or until there is depth 

 enough to allow a sub-foundation of gravel or cinders. Upon this base 

 a layer of cinders or gravel 6 to 8 inches thick is placed and thoroughly 

 rammed. The cement concrete base, made of I part Portland cement, 

 3 parts sand and 5 to 6 parts broken stone or gravel, is then placed on 



