97. A very good rule to fix the thickness of stone foundation walls is, that they shall be at least 8 inches thicker than the wall next above them, for a depth of 12 feet below grade or curb level; and for every additional 10 feet or part thereof in depth, they should be increased 4 inches in thickness. Thus, if the first-story walls are 12 inches thick, the stone foundation walls would have to be 20 inches thick for 12 feet in depth, and 24 inches thick if the depth is increased beyond 12 feet. When of stone, the wall should not be less than 16 inches thick, as a thinner wall than this does not bond well, only small stones can be used, and it cannot be carried to any height.

The thickness of foundation walls in all the large cities is controlled by the building laws. Where there are no existing laws, Table 2 will serve as a guide:

Table 2. Thickness Of Foundation Walls

Height of Building.

Dwellings, Hotels, etc.

Warehouses.

Brick. Inches.

Stone. Inches.

Brick. Inches.

Stone. Inches.

Two stories.......

12 or 1G

20

16

20

Three stories......

16

20

20

24

Four stories.......

20

24

24

28

Five stories.......

24

28

24

28

Six stories........

24

28

28

32