Described is a roof-covering element which can be manufactured inexpensively and which has the appearance, on the outside, of a conventional roof covering, is very light and has an extremely long life, as well as being completely maintenance-free. The element can optionally have excellent insulating characteristics. Its composite design enables a roof covering to be produced which has no thermal-conduction heat-loss points, is impermeable to water and is windproof. It can be laid rapidly, cheaply and extremely accurately in only one operation and can be mounted directly by means of a shaped-section rail on the rafters. Edge elements (verge flashing, eaves) and ridge-head elements, as well as snow-retention bars and mountings for snow elements, rakes can be fitted extremely rapidly and securely. The covering elements are fixed in place by means of a rail with a large cross section, tongue-and-groove design, guide grooves and guide springs, overlaps and 'staggered' laying, thus giving an extremely stable roof covering and adequate strength to resist snow and wind pressure and to be walked on.