Roof covering by making use of flat or curved slabs or stiff sheets with special cross-section, e.g. with corrugations on both sides, with ribs, flanges, or the like of plastics, fibrous materials, or asbestos cement
Roof covering by making use of flat or curved slabs or stiff sheets with special cross-section, e.g. with corrugations on both sides, with ribs, flanges, or the like of plastics, fibrous materials, or asbestos cement