Abstract: Methods and apparatus facilitate the construction of a building using prefabricated building units, each having a horizontal upper exterior surface and a plurality of vertical wall surfaces, wherein at least some of the prefabricated building units have at least one hollow column formwork structure. The prefabricated building units are lowered onto a pre-existing base at a construction site. A first story of the building is created by arranging a plurality of the prefabricated building units adjacent to each other on the base. Structural bearing material is applied to fill the hollow column formwork structures to create structural columns connected to the structural deck. Structural bearing material is applied to the horizontal upper exterior surfaces of the adjacent prefabricated building units to create a single structural deck over the prefabricated building units.