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Foundation Walls
Foundation Walls
Introduction:
In most home construction today the
foundation is poured concrete foundation built on a
concrete footing to support the wall. The house
foundation wall supports the weight of the building
by carrying the load through the footing to the
earth beneath it. Prior to poured concrete
foundations, foundation walls were build using
stone or cement block. There are many older homes
that are still standing that are built on
foundation walls made from stone.
Stone foundations were difficult to build simply
because of the amount of labor involved gathering
the stone and cementing them in place. In more
expensive homes the stone was cut from nearby
granite quarries but this did not ease the burden
of labor. Many of the granite quarried stone
weighed as much as a quarter ton.
Concrete blocks were first used in construction
during the early Roman period but were not used in
the west until the middle of the 19th
century when after the process became mechanized by
using a hand operated press to form the blocks.
Concrete block foundation walls are still used
today by builders to construct foundation walls
although there use is labor intense as compared to
a poured concrete wall.
The concrete block only weighted a fraction of the
weight of stone and was much easier to handle.
Concrete blocks today are made in many different
sizes and styles. Many have a prefinished side that
forms the outside finish of the building.
The down side of a concrete block foundation is
that they are not as strong as poured concrete
foundations and easily crack under shear loads
caused from the shifting earth or strong winds
against the house. However, they are very good at
carrying compression loads especially when the wall
is reinforced with rebar. The standard size of a
concrete block used is 8X8X16 inches and weighs
approximately fifteen pounds
with an insulation R-Value of just 1.11.
A poured concrete foundation wall is usually eight
inches in weight although six inch walls are not
uncommon. For homes that are finished with a brick
or stone veneer the walls are usually ten inches
wide to accommodate the veneer finish.
The insulation R-value of an eight inch poured
concrete wall is approximately 2.0, much better
than a concrete block foundation. In terms of labor
the poured foundation is much less. A standard
eight inch wall that is eight feet high cost
approximately 20% less to construct than a concrete
block wall. With various additives and steel
reinforcement, poured concrete can withstand
tremendous loads, both compression and sheer and
last for decades without cracking.
If you are planning a new home I recommend that you
insist on having a poured concrete foundation. It
is cheaper to build and is stronger than
a concrete block foundation.
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