Abstract: The present invention contemplates a simple and inexpensive, but effective method for constructing straight walls at a building site without use of nails or other fastening means. Appropriately flanged metal I-beam studs are erected with the flanges in the direction of the wall, and expanded polyurethane foam is applied, such as by spraying, to a desired thickness between the I-beam flanges, thereby acting as a fastener and providing insulating properties. A fiberglass-cementitious mixture is then applied to provide a very hard, smooth, waterproof and durable surface of very high fire rating. The invention is equally applicable to interior walls, exterior walls, and roof panels.