Unfortunately, the lateral stability of these lightweight foundations is not as good as concrete and extra-wide framing, spaced narrowly apart, is required to resist the strong hydrostatic pressure exerted from the expansive clay outside the foundation. Too often I have seen these wood foundations noticeably bowing due to undersized framing or improper lateral support at the top of the foundation. If these wood foundations are not properly attached to and braced by the main floor joists and beams, inward bowing is almost a certainty.

Concrete is installed in these forms much the same way as with removable plywood forms, but the difference is that these forms remain in place after the concrete has set. Re-bar is still required for installation with the concrete for strength. Little else is required once the forms are set in place, except temporary bracing to prevent movement of the forms from the heavy, wet concrete.

Just like either of the other two types of foundations explored, ICF foundations still require the application of damp-proofing or a membrane on the exterior to prevent moisture intrusion. All in all, ICF foundations appear to be a very good choice for modern homes due to their excellent insulation qualities while still incorporating the strength and durability of concrete.