Building With Insulated Concrete Forms

Green Architect

We love things that can serve more than one purpose, and one building material—nsulated concrete forms—do just that. Insulated concrete forms are rigid foam forms that hold concrete in place during curing and remain in place to insulate the concrete walls. The lego-like foam blocks are a simple construction material that provides an energy-efficient, durable building.

The Difference
Traditional foundation walls are made by pouring concrete in temporary forms. These forms are removed and then insulation is added to the interior of the foundation walls, if an insulated foundation is desired. Insulated Concrete Forms (ICFs) eliminate the need for the temporary forms and separate insulation system, because the ICFs are an all-in-one system — simply pour the concrete between the ICF forms, and the result is a continuous insulated foundation. ICFs can not only replace traditional foundation walls, they can also be used to replace traditional stick or block exterior walls, to build the entire exterior envelope.

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Construction
Typically ICF walls consist of two parallel boards of rigid foam insulation. ICFs are stacked like lego blocks to form the exterior walls of a home, and then are reinforced with steel and filled with concrete. ICFs can be installed as just the foundation walls, or they can be used from foundation to roof rafters to create all the building walls. Used this way, the ICFs can provide essentially a seamless, fully insulated, reinforced concrete wall building. Window and door openings are simply blocked out where needed, and can be created in any size. The exterior and interior can be sheathed with any traditional material, and once construction is complete, the building looks just like any other normal home.

Advantages
The walls of a properly-constructed ICF home are resistant to high wind loads and can be designed for most seismic zones. ICF constructed buildings are highly durable and long-lasting because they are structurally very strong, more resistant to rot, moisture, termites and other pests. Because of the high mass and insulation, ICFs also help contribute to an overall quieter building. Construction costs can be higher than traditional building, however many experienced construction teams often prefer ICFs because they are much faster and easier to build.

Disadvantages
However, these thick walls mean a sizable floor area is lost to the footprint of the thicker walls. Additionally, it is possible to get a just as insulated and air-tight building with ICFs use only for foundation walls, and traditional insulated stick-frame above grade walls. ICFs can have a higher upfront cost than traditional wall construction; however, this may be offset by lower energy use as a result as a more efficient building envelope.

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(Images: Above the Jump: Nathan Kipnis Architects; Below the Jump: PolySteel UK)