There are several Insulated Concrete Form (ICF) block systems on the market. Most use Expanded Polystyrene (EPS) blocks or panels that are laid up, installed with rebar, and poured with concrete. Other systems use recycled foam and a concrete mix to create the blocks or waste wood that is shredded and combined with a concrete mix to create the blocks. Concrete-filled ICF block walls are very strong and earthquake-resistant. They also have high insulation values and are airtight and moisture resistant.