Insulated Concrete Forms

Written by Nicholas Kamuda
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One building system that has received considerable attention in the homebuilding arena of late is the ICFs, or insulated concrete forms, building system. Insulated concrete forms are Styrofoam blocks that are used as concrete forms in the production of cast-in-place concrete walls. Once cast, the Styrofoam remains in place, acting as a shield for the concrete during curing and as insulation once the concrete has set.

ICFs have been popular in Europe for over 30 years, and have been used for both residential and commercial applications. Despite their considerable success overseas, they remain relatively unknown in the United States, having only been introduced here around 15 years ago. Thanks to the efforts of supporters of ICFs in the building community, however, awareness of the system and use is growing rapidly.

One organization that has been promoting ICFs in the United States since early on is the ICFA, or Insulated Concrete Form Association. Two former Portland Concrete employees formed the ICFA when they recognized that, despite massive potential, ICFs were slow to catch on in America. The ICFA has been involved in training, promotions, and efforts to standardize codes for insulated concrete forms since 1995.

Some Benefits of Using Insulated Concrete Forms

There are many benefits to ICF construction over standard, traditional home framing techniques. For example, building with insulated concrete forms allows builders to combine the framing, sheathing, and insulating stages of homebuilding into a single stage. Experienced teams can construct the exterior walls of an ICF home even quicker than a wood-framed house.

From the homeowner's perspective, the primary attraction of ICFs may be their large R-value. R-values of building materials and walls describe the thermal insulation properties of the material. The higher the R-value, the greater the thermal insulation that the wall offers--for example, one fiberglass blanket may have an R-value or R-11, whereas two layers of the blanket will produce a value of R-22.

Walls constructed with insulated concrete forms have an average of twice the R-value of wood-frame walls. In addition, the thermal mass of the concrete (the ability of the concrete to disperse heat energy, allowing it to act as a buffer during temperature swings) and the airtight quality of the walls increase their R-value ever more. Some houses use ICF construction for both below-grade and above-grade walls, allowing builders to create a solid external shell, forming a tight thermal envelope around the house and greatly reducing energy expenditures.

Amazing Durability

Houses that are constructed with insulated concrete forms are also amazingly durable, often sustaining little structural damage over decades of use. The concrete may be able to withstand hurricane-force winds, making the southeastern U.S. a popular place for ICF construction. The concrete and foam components of some brands of ICFs also have high fire ratings, sometimes topping three hours.

Building With Insulated Concrete Forms

One of the strengths of ICF construction over traditional concrete construction is the ability that customers have to modify their designs to make them as elegant as possible. Insulated concrete forms are usually light enough that they can be handled easily, and can bed cut to make complex forms such as radius walls and large window openings. Moreover, many companies have built businesses on further simplifying the already straightforward installation of ICFs, offering specialty pieces and installation materials.

Some popular products include finishes, and window and door systems. Usually, ICFs require little finishing, especially on the interior, where a good coat of plaster may be all that is needed. Homeowners can decide on any of a number of exterior improvements, however, including hard coatings, color, and textured finishes. Windows and doors must be blocked out with customized bucks, so prefab packages including bucks, the windows, and sealing materials may greatly simplify the building process.

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