Abstract: A modular unit for use in constructing a framework of a building consisting of a plurality of modular units in connected relationship having a floor portion with longitudinal and lateral perimeter members. The longitudinal and lateral perimeter members are joined by joists interconnecting the perimeter members and welded thereto with a corrugated metal decking overlying the joists. The joists are made from a sheet steel configuration which has been bent into a Z shaped configuration with upturned lateral portions. Plywood sheeting overlies the corrugated metal decking. The entire structure incorporates wheel wells for the enplacement of wheels so that the modular unit can be towed into place. Trusses in the roof are support the roof and are attached at the cord sections to upright structural columns. The modular unit are held together by bolts which can be later secured by welding between the perimeter members, the columns, and the truss areas.