Insulating Concrete Forms (ICFs) have been around since the late 1960s, but have garnered more attention over the last several years as an increasing push for green building and energy-efficient homes has taken hold in the construction industry.
Insulating Concrete Forms (ICFs) have been around since the late 1960s, but have garnered more attention over the last several years as an increasing push for green building and energy-efficient homes has taken hold in the construction industry. As their name indicates, ICFs are forms for constructing cast-in-place concrete walls, floors and roofs. Made of expandable polystyrene (EPS) foam, the forms are hollow and modular, with an interlocking structure that allows them to be stacked without the use of mortar as a binder. Steel rebar is placed at regular intervals, running both horizontally and vertically, to add support and strength. Concrete is then poured inside the hollow forms. Left in place after the concrete cures and dries, the forms serve as excellent thermal and acoustic insulation. They also allow space to run electrical wiring and plumbing pipes.
When compared to traditional wood or metal frame construction, ICFs offer numerous advantages:
- Flexible design – the modular nature of the forms allow for unconventional shapes to be constructed
- Thermal Resistance – the multi-layers of materials, with concrete sealed between two layers of foam, provides exceptional insulation
- Sound absorption – only about one-third of the noise that would pass through a wood or steel frame wall makes it past the concrete forms
- Energy efficiency – ICFs reduce heating and cooling costs
- Strength – The steel rebar and concrete combination allows for extra resistance against forces of nature, including hurricanes and earthquakes
- Durability – The forms allow for a variety of finishes, inside and out, including stucco, brick and vinyl
- Reduced building time – the modular construction and integrated insulation allows for speedy construction
Costs (and disadvantages)
The cost of adding the steel rebar is the catch in what otherwise is typically an economical construction. Cost estimates range anywhere from $1.00 to $5.00 per square foot in additional expense. Proponents of ICFs point out the extra initial expense can be offset by future energy savings. Renovation can also be a costly drawback, as structural changes such as adding or moving doors and windows incur extra effort and expense.