A building element (10) is formed from sheet material having opposite major surfaces (11, 12) that extend between longitudinal edges (13, 14). Margins of the sheet adjacent the longitudinal edges are turned out of a mid-plane of the sheet to form opposite profiled sections (15 and 16). The major surfaces (11, 12) of the building element have different surface characteristics, and one profiled section has one of the major surfaces as its outer surface, and the other profiled section has the other major surface as its outer surface.