Insulated Concrete Forms (ICF) are stay-in-place interlocking foam block products that work by sandwiching a pad of concrete and steel reinforcement to provide both structure and insulation for a home. In most cases the product is manufactured with expanded polystyrene (EPS) in a process where precision molds are filled under pressure. With cement, steel reinforcing and two-inches of EPS on each side the result is a war, airtight sound-proof wall that is not affected by water, weathering and insects.
What Are ICF's?
The vast majority of ICF products have an interlocking system somewhat like interlocking childrens blocks. There are web centers that hold the outside foam pieces. There are also specialty pieces like for corners, junctions and to provide a platform for floor joists. The size of the webs decide the spacing of the concrete: 6”, 8” etc.
The plastic spacers not only provide an equal cavity for the concrete they also hold the steel rebar in place during the pouring of the concrete. Once the concrete cures ICF’s provide more than great insulation and sound barrier qualities but the plastic spacers provide anchors for interior drywall and, on the outside, stucco, siding or brick.
High R-Value
In a study by the Insulated Concrete Form Association, four inches of ICF foam encompassing a five-inch concrete wall is rated at or above R-17. R-value is the measurement of how well a product resists the transference of heat to the outdoors. In addition, air leaks are almost non-existent because of the solid block created by the foam insulation and the concrete. Unlike tradition walls there are no places for warm air to escape and no convection currents within the walls that are found in many older, frame-built dwellings with fiberglass insulation Another quality of ICF construction is thermal mass. This means that the interior of a home is protected from the extremes of outdoor temperature, either heat or cold.
Money Saving Walls
With the combination of very high R-values, an efficient thermal mass and very low air leakage insulated concrete walls can save the homeowner from 25% to 50% over wood or steel-framed structures. You then choose the type you want by price, style, design benefits and/or availability.
The cost of installed insulated concrete walls is around 10% more than a weather-tight, stick-framed home. This means that the home has been framed in and the roof, doors and windows put in. However, this can be made up in under five years just with energy savings. Then there are the considerations of having a comfortable, low-maintenance home.
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