a dry mortar and the backing then placed; washed with 

 a grout, stuccoed, tooled or chemically treated. Mineral 

 colors not over 10% by volume can be used. A % In. finish 

 (never less) can be applied to a structural floor by means 

 of a joint made by scrubbing the floor with acid. Cork 

 floats are used in rubbing walls. 



Maximum Span for Ceiling Joists (Kidder.) 

 Total Load, 20 pounds per square foot. 



Total Load, 24 pounds per square foot. 



CRACKS SHRINKAGE. 



Cracks are due to the cement being unsound, concrete 

 setting in air, mortar flushed to the surface by troweling, 

 and changes in temperature. When large areas are con- 

 sidered, contraction joints should be provided. Concrete 

 thoroughly reinforced with metal can elongate .0018 before 

 It cracks, or a fall of temperature of 250 deg. Concrete 

 at 200 Ib. in tension and elastic limit of steel at 65.000 Ib. 

 then the area of steel required would be 1-275 of the num- 

 ber of square inches in the wall. 



