Method of constructing a prefabricated room element and a building of a plurality of said elements

A method of constructing a building from a plurality of transportable prefabricated room elements comprising prefabricating each of a plurality of room elements by preparing a floor panel member having a horizontally extending channel therein, preparing a vertical structure having a vertically extending channel therein, preparing a load-bearing frame comprising a horizontal load-bearing beam and a vertical load-bearing beam, and assembling the floor panel member, the vertical structure and the load-bearing frame with the horizontal beam engaged in the horizontally extending channel and the vertical beam engaged in the vertically extending channel at a location remote from a building site to produce a transportable prefabricated room element, transporting the plurality of room elements to a building site, and mounting the elements in face-to-face relation to form a building.