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Concrete / Foam Block Houses


I plan to build a new house or add a large room over a basement. I want super-insulated
walls and extra strength to resist tornadoes and hurricanes. What is the best
construction method for me?

-Paul K.


Concrete/foam block house construction is one of the
best new house construction methods available and it would be an
excellent fit with your needs. It produces super-efficient
airtight walls with insulation values up to R-32 and can resist
tornado- and hurricane-force winds up to 150 mph.

As compared to a similar-sized stick-built house constructed with
2×4 walls, a concrete/foam block house results in a much lower
utility bill, up to a 50% savings. These tremendous monthly
savings can easily pay back any higher initial construction costs
quickly. Since the construction methods are so simple, you can
help with some of the basic setup and reduce the construction
labor costs.

These utility bill savings result from more than just the higher
wall-insulation levels. By their basic design concept, with
interlocking tongue-and-groove blocks, concrete/foam block houses
are very airtight.

A secondary benefit of the heavy concrete and the airtightness is
the noticeably reduced outdoor noise transmission through the
walls. The heavy mass is most effective at blocking the deeper,
low-frequency type of rumbling sounds. Since these houses are so
efficient, they require smaller, less expensive furnaces, air
conditioners, or heat pumps to be installed.

With the heavy concrete structure inside the walls, the energy
savings and efficiency can be even greater in the summer. The tons
of concrete act as a thermal mass to moderate temperature swings
indoors throughout the day and night. This naturally maintains
more even indoor room temperatures and minimizes some of the peak
electricity demand on hot afternoons.

The simplest, and oldest, type of concrete/foam block construction
is the "Legos" method. Basically, the wall is
constructed of large hollow, lightweight (5 to 10 lbs.), expanded
polystyrene foam blocks, similar to common foam coolers. You just
stack up the interlocking foam blocks to make the wall. This is
the part of construction that you can help with.

Once the walls are completely stacked, openings for windows and
doors are easily cut into the foam and the openings are framed.
Next, reinforcing steel rods are slipped inside the hollow block
cavities. A concrete truck, with a pump attachment, pumps the
concrete into the openings at the top of the wall.

To reduce transportation costs of the large hollow blocks to your
building site, many manufacturers are now offering half blocks or
special flat insulating foam panels. These blocks or panels are
assembled into full blocks at your building site and the house is
assembled. Check with your local professional builders’
association for ones that are familiar with these methods.

These half blocks are assembled in various manners. Some true half
blocks have interlocking teeth on the inside of the mating blocks
that slide together. Others use a plastic or metal web to position
and attach the two halves or flat foam pieces together.

The exterior of a concrete/foam block house can be finished with
any traditional finishing material-brick, siding, stone, stucco,
etc. When using the half-block design, the exposed end surfaces of
the connecting webs provide a strong attachment point for interior
drywall and exterior materials.

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