Stone foundation walls should be at least 8 in. thicker than the wall above, for a depth of 12 ft. below grade or curb level; for each additional 10 ft. or part thereof in depth, they should be 4 in. thicker. Thus, if the first-story walls are 12 in., the foundation should be 20 in. thick if 12 ft. deep, and 24 in. thick if over 12 ft. Stone foundations should not be less than 16 in. thick; a thinner wall 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, the following table will serve as a guide:

Thickness Of Foundation Walls

Height of Building.

Dwellings, Hotels, etc.

Warehouses.

Brick. Inches.

Stone. Inches.

Brick. Inches.

Stone. Inches.

Two stories

12 or 16

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

The table on page 179 is a tabulated summary of the New York Building Law in regard to walls, and may be safely taken as a standard. It applies only to buildings having solid masonry walls, and not to those of skeleton-construction type, in which the walls are carried on the framework.

Thickness Of Walls Required In New York. Dwellings, Hotels, Schools, Etc

Height

Above Curb.

Feet.

* Stone

Foundation.

Inches.

Outside and Bearing Walls.

Up to 35

20

Basement 12"; 8" above.

35- 50

20

† All 12".

50- 60

24

First story, 16"; 12" above.

60-75

24

Lower 25' 16"; 12" above.

75- 85

28

Lower 20', 20"; next 40', 16", above, 12".

85-100

32

Lower 35', 24"; next 35', 20"; above 16".

100-115

36

Lower 25', 28"; next 25', 24"; next 40', 20"; above 16".

‡ Warehouses, Factories, Etc.

Height

Above Curb.

Feet.

* Stone

Foundation.

Inches.

Outside and Bearing Walls.

Up to 40

20

All 12".

40- 60

24

Lower 40', 16"; above, 12".

60-75

28

Lower 25', 20"; above, 16".

75- 85

32

Lower 25', 24"; next 35', 20"; above, 16".

85-100

36

Lower 25', 28"; next 25', 24"; next 25', 20"; above, 16".

*If brick is used, width may be 4" less. For foundations over 10' deep, thickness must be increased 4" for each additional 10' or part thereof.

† Non-bearing partition walls. less than 50' high, may be 8".

‡ If clear span is over 25', all bearing walls must be 4" thicker for each 12 1/2 over 25 span.

For heights greater than those given, the lower part must he 4" thicker for each 25' or fraction thereof in height, the upper 115' or 100', respectively, remaining as given in table.