E04D3/00—Roof covering by making use of flat or curved slabs or stiff sheets
E04D3/36—Connecting; Fastening
E04D3/361—Connecting; Fastening by specially-profiled marginal portions of the slabs or sheets
E04D3/362—Connecting; Fastening by specially-profiled marginal portions of the slabs or sheets by locking the edge of one slab or sheet within the profiled marginal portion of the adjacent slab or sheet, e.g. using separate connecting elements