Abstract: This specification discloses an improved structural section for use as a beam or rafter and comprising two similarly profiled metal sections joined together so that their profiles define a central box-section and a plurality of spaced stiffener members located within the box-section to render the box-section substantially rigid. The box-section may be of any preferred shape. For example, two metal sections with V-shaped profiles may define a central square box-section or two metal sections with trapezoidal shaped profiles may define a generally hexagonal box-section. The specification also discloses the use of a connector plate for transferring horizontal loads applied to the section to the box-section and comprising a cut-out on one side of the plate having a shape corresponding to the profile in one of the metal sections. The plate is shaped to engage the top of the section to positively locate the plate in position.