blocks or underpinning on 4 foot center under all 

 outside sills; on 6 foot centers under all exterior 

 sills and girts. Where underpinning on short 

 centers are necessary, add sufficient material to the 

 lumber order list to provide for them. 



Foundation blocks shall ordinarily be of 

 large flat stones of sufficient thickness to raise 

 the sills at least 6" above the ground. The sills shall 

 be placed directly on these stones. If stones of 

 appropriate size are not available, concrete or masonry 

 blocks shall be provided. See the "Concrete Section"- 

 Foundations, of this Circular. A dry waH shall be 

 set up between the foundation blocks under all outside 

 sills. If the building site is not level, and if to 

 grade it level throughout, is impracticable, foundations 

 shall be either of - 



(a).- 6" x 6" heart cedar, redwood or Douglas fir 

 underpinning, set upon substantial flat stones of 

 sufficient thickness to project at least 4 inches 

 above the ground. Wood blocks should never be used 

 for footings under foundation posts. 



(b).- If substantial stones are not available, a 

 masonry footing should be provided. For masonry, use 

 only hard stones, preferably flat ones. All should be 

 carefully imbedded on their broadest faces in mortar 

 of 1 part cement and parts coarse, clean, sharp sand. 

 Each layer should be well filled and flushed up on both 

 sides and firmly bonded together. The tops should be 

 made level to receive the underpinning. See Table 

 No. C-4. 



MATERIALS. 



All structural materials should conform as 

 closely as possible to the specifications given in the 

 builder's list and lumber order list. That minor 

 deviations must sometimes be made is recognized as un- 

 aviodable . 



'10- 



