Abstract: A modular house is constructed with Engineered Structural Modular Units (EMSU's) made from Stucturally Engineered Oriented Strand Boards (SEOSB's). Unitized structures are formed from modular units comprising two SEOSB panels with internal webbing for floor, wall, ceiling and roof modules; and adapter units such as corner adapter units, U-channel adapters, alignment connectors, trim adapters, and roof support adapters. Window and door openings can be cut on-site during construction. Any insulation meeting local building code requirements can be installed on-site. Standard electrical, plumbing, and mechanical products and procedures can be used as required by local building codes. All roofing and exterior wall coverings that meet local building codes can be used as required by architectural design.