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A
home’s foundation is in direct contact with the ground and
joins the buildings structure with the underlying zone of
soil or rock. The foundation’s job is to transfer the
structures load to the underlying soil or rock, without
excessive settlement or movement. Movement of the soil
beneath a home can severely damage the foundation. That’s
why the soil beneath your home is often referred to as your
second foundation.
 Slab-on-grade
foundation
Slab-on-grade foundations are shallow foundations that are
most often constructed of reinforced concrete. Slab-on-grade
foundations can be built quickly and are relatively
inexpensive to build. The function of a slab-on-grade
foundation is not to resist or limit the amount of heave
that might occur beneath a slab foundation, but to move up
and down with the shrink and heave. Slab-on-grade houses do
not have basements.
Shallow foundations are susceptible to seasonal movement
from rainfall, drought, freeze/thaw cycles, and temperature
changes and transpiration of moisture thru the roots of
large plants and trees.
Pier
and beam foundation
 Pier
and beam foundations, as the name suggests, are a concrete
footing and pier which support wood beams and floor joists.
These foundations usually have crawl spaces underneath the
home.
Basements are most often constructed in northern climates
where freeze thaw conditions occur and the footing depth
must extend beneath the frost line- often four or more feet
below the surface. In many of these cases, builders will go
ahead and excavate for a basement and build basement walls
that provide the support for the house. The bottom of the
basement is typically below the depth over which the
majority of the soil’s shrink or swell due to climate
occurs. Basements can suffer basement floor heave and
lateral wall movement, however.
Deep foundations reach depths that are not normally affected
by seasonal environmental changes and are considered to be
out of the zone of influence.
There are a multitude of other types of both shallow and
deep foundations.
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