| Dear Ms. Builder: My husband and I are in the planning stages of
our new house. We are considering using a precast concrete foundation. The
builder says that it is better and can be built faster. Is this correct? -
Karen J.
Dear Karen: It sounds as though you have a very progressive builder
who understands the advantages of using precast concrete panels. This is
particularly true if you plan to have a basement that you will finish for
living area. Precast concrete panels can also be effective for aboveground
walls in warmer areas with no basements.
Precast concrete panels have been used for many years in commercial and
industrial construction, but it is a newcomer to residential construction. New
construction methods are always much slower to diffuse into residential
construction. This is due to reluctance of many builders to accept new methods
and to the hesitance of inspectors to change building codes.
Make sure that your builder has had some experience with this construction
method. It is not difficult to erect the precast panels, but in order to
realize all the advantages of this construction method, they must be level,
aligned and properly sealed.
When you think about it, it makes sense to use precast concrete panels. They
are made in a factory with strict quality standards and controlled conditions
not subject to rain, hot and cold or builder errors. Most of the panels use
superstrong 5,000 psi (pounds per square inch) concrete instead of 3,500 psi
concrete commonly used in poured foundations.
Another advantage of using precast concrete is that it has steel reinforcing
rod in all directions, not just horizontally around the band. Poured concrete
foundations often have only a couple of pieces of reinforcing rod at the top
and at the bottom.
In poor soil conditions, this can lead to future problems with cracks and
leaks. If you and your builder do choose a poured foundation instead, ask for
vertical reinforcing rods too.
You may have to do a little research to find a supplier of precast concrete
panels in your area. They are very heavy and bulky, it does not make economic
sense to ship them over long distances. Since your builder recommended them, he
or she probably has a source for the panels.
If you have a problem finding them, contact these two major manufacturers of
precast concrete panels - Superior Walls of America (800-452-9255) and
Thermal-Krete (716-434-6157). They license many concrete companies across the
country to cast their panel designs for them. Hopefully you can find one nearby
to minimize transportation costs.
Even though precast panels cost somewhat more, there can be substantial
labor savings. Once the foundation is dug and the crushed gravel base is laid
(concrete footers are not always used) the entire foundation can be erected in
one day. Crushed gravel formed a very stable base that distributes the weight
of the house over a large area.
In contrast, concrete cannot be poured in the rain and construction delays
can get costly. If a standard concrete foundation is poured in less than
optimal conditions, the strength of the concrete can be compromised. There can
also be cold joints where one pour of concrete begins to set before more is
poured against it.
Even if you do not finish your basement or if you are using a crawl space,
closed cell foam insulation panels on the inside of the panels will save energy
year-round. Cavities between the formed concrete ribs provide space for wiring
and plumbing. For additional insulation, the cavities can be filled with
additional fiberglass insulation before finishing.
Many precast concrete panels, designed for residential foundations, have
pressure-treated lumber nailers on the inside of the walls. This makes
finishing it with drywall very easy. Owens Corning (800-438-7465) also makes a
professionally installed wall insulation/finishing system for concrete walls.
Send your questions to Ms. Builder, 6906 Royalgreen Dr., Cincinnati, OH 45244 or
visit www.dulley.com/msbuilder.
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