Insulating Concrete Forms (ICFs) are a formwork for concrete that stays in place as permanent building insulation for energy-efficient, cast-in-place, reinforced concrete walls, floors, and roofs.
The forms are interlocking modular units that are dry-stacked (without mortar) and filled with concrete. The forms lock together somewhat like Lego bricks and serve to create a form for the structural walls or floors of a building. Concrete is pumped into the cavity to form the structural element of the walls. Usually reinforcing steel (rebar) is added before concrete placement to give the concrete flexural strength, similar to bridges and high-rise buildings made of concrete (see Reinforced concrete). The forms are filled with concrete in 1–4 foot "lifts" to reduce the risk of blowouts like with other concrete formwork. After the concrete has cured, or firmed up, the forms are left in place permanently. The benefits of these EPS forms are:
- Minimal, if any, air leaks, which improves comfort and less heat loss compared with walls without an air barrier
- Thermal resistance (R-value) typically above 3 K·m²/W (in American customary units: R-17); this results in saving energy compared with uninsulated masonry (see comparison)
- High sound absorption, which helps produce peace and quiet compared with framed walls
- Structural integrity for better resistance to forces of nature, compared with framed walls
- Higher resale value due to longevity of materials More insect resistant than wood frame construction
- When the building is constructed on a concrete slab, the walls and floors form one continuous surface; this keeps out insects.
- Concrete does not rot when it gets wet
- Reduces HVAC operating costs from 30%-70%
- Construction methods are easy to learn, and manufacturers often have training available
- ICF structures are much more comfortable, quiet, and energy-efficient than those built with traditional construction methods.
- Designing and Building with ICFs help your construction project attain Leadership in Energy and Environmental Design (LEED) Green Building status.
- Insulating Concrete Forms create a monolithic concrete wall that is 10 times stronger than wood framed structures.