Page 219 - Masonry and Concrete

Footings, Foundation Walls, Basements, and Slabs
218 CHAPTER SIX

mum slope, area drains or earth swales
must be provided to ensure drainage
away from the structure. Like basement
floor slabs, slabs-on-grade are often sup-
ported on gravel drainage beds. Because
3 1 /2" MIN. the footings are shallow and the slabs set
above grade, soil moisture is usually not
a problem except on poorly drained sites
or where the water table is very close to
the ground surface, but water vapor dif-
fusion from the soil must be considered,
GRAVEL
DRAINAGE BED and perimeter insulation may be neces-
sary in colder climates. Soil moisture,
FIGURE 6-27
insulation, and vapor retarders are dis-
Basement slabs.
cussed below.

6.5 Drainage and Waterproofing

Water moves through the soil by gravity flow and capillary action and
exerts hydrostatic pressure against basement walls and slabs which

INTERIOR
BEARING WALL

3 1 /2" MIN.

W

W MONOLITHIC SLAB
WITH INTEGRAL FOOTING
FIGURE 6-28
Slabs on grade. (from Council of American Building Officials One and Two-Family Dwelling Code,, Falls Church, VA).

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