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INSULATED CONCRETE FORMS
As the saying goes, "Build a better mousetrap and the world will
beat a path to your door." The emerging popularity of building
Typical ICF
corner form |
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homes with Insulated Concrete
Forms (ICFs)
seems to be proving the old adage true. Of course, for home builders,
erecting forms and pouring concrete walls is nothing new, at least
below grade. But the advent of lightweight, stackable, interlocking
forms which also incorporate interior and exterior insulation has opened
the market for ICFs for virtually all exterior wall applications. The
list of major homeowner benefits is impressive:
- Strength: ICF
walls benefit from concrete's inherent structural qualities, particularly
important in regions affected by severe weather.
- Lower Utility Bills: The
combination of a continuous concrete wall plus the integral interior
and exterior insulation provides superb energy efficiency.
- Indoor Environmental Quality: ICF's
energy efficiency translates into more even, consistent temperatures
throughout the home. Outdoor pollutants can be kept to a minimum
- particularly important to allergy sufferers. A fresh air exchanger
(strongly recommended) helps regulate humidity in the home for
maximum comfort.
- Soundproofing: With
several inches of concrete sandwiched by foam insulation, ICF homes
are typically quieter than neighboring homes built conventionally.
Adapting
home plans to ICF Construction
Design 2326 built with Insulated Concrete Forms. |
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ICF
construction is compatible with virtually all home designs. Once
built, ICF homes are indistinguishable from their traditionally-framed
counterparts. Yet, there are some differences in building homes
with ICFs.
The most obvious difference is the increased wall
thickness. Due to the thicker exterior walls, the overall width,
depth, and square footage of a home is usually increased in order
to not crimp on room sizes.
Due to increased overall dimensions, the roof system
will get bigger for an ICF home. Typically, the roof geometry will
stay basically the same, but the ridge heights will increase. Of
course, the foundation changes as well. Additionally, wall thickness
varies among ICF manufacturers. Check with the original home plan
designer or architect with regard to modifying a particular set of
plans to work with ICFs. Or, ask your ICF manufacturer about modifying
plans for ICF construction. Many of the manufacturers have a network
of designers or architects familiar with ICF building who can modify
your plans. Expect to spend between $750 and $1500 to modify the
plans or your local ICF distributor may be able to modify the plans
for you.
Factors To Consider
Basement waterproofing materials for an ICF basement may need to be different
(i.e., petroleum-based tar would melt the exterior foam on the ICF form.)
Windows and doors will need to be ordered with wider jamb extensions to
accommodate the increased wall thickness. Another major factor is the level
of manufacturer support, including training, on-site and technical support,
and marketing materials.
Cost
Industry estimates suggest ICF homes may cost 0 to 10% more to build,
depending on the manufacturer and other factors impacting local building
costs. Importantly, the increased construction costs may be offset
by lower utility bills. For example, a $200,000 30-year mortgage at
7% translates to $1330 per month (P&I). If building the home using
ICFs added $8,000 to the cost of the home, the monthly payment would
increase to $1,383. If the energy efficiency of the ICF home reduced
heating and cooling costs by an average of $53 per month, the lower
utility bills cancel out the increased construction costs.
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