Abstract: A metal building has panelled walls and roof, being based upon a frame incorporating a water barrier, to guide any water leakage outwardly of the building. The panelling for a major area such as the roof consists of roll-up prefabricated panels in permanently connected relation by way of knuckle joints, each panel portion having a plurality of corrugations to facilitate ready rolling and unrolling of the predetermined length of panel. This type of panelling may also serve as wall panelling, as well as for the roll-up door of the building. Where planar type (non-corrugated) wall panels are used, the panel end or ends may have a flange portion, to preclude bowing of the panel. The wall panels, in combination with corner piers of the building, are load bearing, to support the roof and applied snow loads. The corner piers may consist of two planar panels for easy shipping.