Abstract: A prefabricated constructional component formed by a flat self supporting panel bent in a V shape and adapted to form a vertical section of the assembly formed by an outer wall of the construction and by the roof pane extending this wall upwardly is characterized in that it is in the form of a wooden chassis (37) with closed contour defining two flat panes connected together in a V shape, this frame being defined laterally by bonded laminate beams (38) bent into a V shape whose opened out length is greater than 5 meters, and each pane being closed by two flat parallel facings (43) of which at least the one disposed on the outside is formed from plywood.