Abstract: A system for constructing a building is disclosed which employs various side wall, corner and roof forming elements adapted to be joined in interlocked sealed relation without need for nails or skilled craftsman. The various elements may be made from relatively inexpensive materials, such as reclaimed materials indigenous to the site of construction, generally lighter than conventional building materials such as brick and mortar, and are therefore particularly suitable for use in countries of relatively low economic wealth. Furring clips may be formed on the internal surfaces of the wall and corner forming elements to facilitate attachment of interior wallboards and the like, while the external surfaces of the various elements may be textured to simulate a desired exterior appearance.