Many builders or homeowners may be interested in insulating concrete forms or insulating the existing concrete in their homes. Though concrete has great thermal mass, is isn't much of a thermal insulator, and often has relatively low R-values. By supplementing the concrete with inexpensive but effective insulators such as foam, however, builders and homeowners can drastically reduce the amount of heat or cool lost though concrete walls.

Thermal mass is the ability of a material to store heat energy during a shift in temperature. It does so by absorbing heat or cool throughout, spreading the energy evenly though its mass and retaining that energy. Insulating the concrete (or, when pouring, insulating concrete forms) can give the it good thermal insulation properties to that take advantage of its high thermal mass. This can raise the R-value, or quality of the thermal insulation, of the wall as a whole.

Building Systems that Use Insulating Concrete Forms

Some concrete forms are designed to be insulators. These insulating concrete forms, usually called ICFs, are meant to be stacked on top of one another along the perimeter of a foundation to form the walls of a building. Once in place, they are reinforced with scaffolding, steel, and rebar, and then filled with concrete.

The forms protect the concrete while it's drying, allowing it to reach its full structural strength. In some projects, ICFs are used to build from the foundation up, including above-grade walls and even second-story walls. They can be customized to form radius walls and ledges, and can be modified to incorporate large windows and doorways more easily than standard concrete forms.