Abstract: A building module for housing purposes comprises a rigid, rectangular, three-dimensional truss formed with four steel end columns and steel beams extending between the columns. The modules may be combined with similar modules to form building structures. Each module includes a floor panel extending between the four end columns, wall panels, and a roof panel extending from two of the end columns, parallel to the forward column and terminating a spaced distance from the two end columns. A first rectangular folding panel has one end hingedly attached to the edge of the roof panel termination and a second rectangular folding panel, larger than the first rectangular folding panel, has one end hingedly supported between the two end columns.