ICFs can replace conventional stud construction for basement and side walls. The forms usually consist of concrete between polystyrene foam, although other form materials such as polyurethane, recycled wood, and cement mixtures are sometimes used. There are three general types of ICF construction: flat ICF wall, where the poured concrete surface is flat; waffle grid, where the concrete has varying thickness; and open grid, where the concrete forms a grid.
Builders have found that structures using ICF systems had higher costs than conventional construction -- raising the sales price between 1 and 5 percent. Construction crews needed some training but became comfortable with the new techniques by the third form-built house. The houses sold readily, and builders expected to continue using this type of construction.