Abstract: This invention relates to sheet metal buildings of relatively large size and more particularly but not exclusively to processes and apparatus for cold-forming elongate building elements of such buildings and methods of building construction. The invention provides in one aspect cold-forming dies 30, mounted on intermediate transverse members 21 of a frame 1, comprising a set of coextensive generally in register dies between which the strip is received. The set comprises a male die 22 having a concave leading edge 24 and a female die 23 having a convex leading edge 18. The male die 22 and female die 23 are driven towards one another to plastically deform the strip 6 into a channel section. The concave leading edge 24 is provided with a coextensive protrusion 26 and the convex leading edge is provided with a coextensive recess 27.