Abstract: A room sized building module made up of a three dimensional skeletal frame comprising wall frames and a ceiling frame constructed as a unitary integral structure adapted to be attached or moulded to a floor, the whole frame being constructed in a reinforced concrete matrix material, the frame being formed around and bonded to a premade sheet of lining material strong enough to be self supporting between the frame members, the lining material and the frame combining together structurally to provide a rigid transportable module. The ceiling of the module is preferably domed.