Exterior, House Building Type, Flat RoofLine, and Prefab Building Type Opting for a lightweight, super stable design that eschews traditional weighty materials, the architects created steel-reinforced panels of expanded polystyrene foam (EPS)to form each of the addition’s seven modular parts. They now top a preexisting concrete garage that the architects had previously converted into a three-bedroom home.  Photo 4 of 11 in Across the Ocean