Abstract: A floor frame assembly, formed principally of wood material, has two load-bearing outer beams and front and rear end members defining a periphery and a plurality of transverse load-supporting trusses connected normal to the outer beam between the end members. In a preferred embodiment, each truss has an upper elongate member, a shorter central elongate member attached parallel thereto by vertical cross-braced elements, and on either side of the central member a braced vertical member spaced therefrom to provide gaps of predetermined height and width. Each truss also has an end portion of the upper elongate member in cantilever form for contact thereat with a load-supporting surface at the permanent location of the floor assembly, so that additional external beams or continuous wall surfaces to support the completed floor frame assembly and any superstructure thereon is rendered unnecessary.