Abstract: In a metal wall comprising prefabricated modules joined together by double lap joints, an insulating strip, provided on each prefabricated module, is clamped between opposed transverse flanges which connect a laterally extending internal web of the joint to one of the faces of the module. The insulated strip extends from between the flanges into a space between the laterally extending internal webs of the joint, and thereby provides insulation between the opposite faces of the module, as well as between the module and its adjoining module. A screw fastener is used to secure the internal webs together, and a space between adjacent edges of faces of the adjoining modules is situated opposite the internal webs so that the fastener can be introduced through the space and concealed by a tamper-resistant caulking material introduced into the space.