Roofing felt is frequently used on flat or very slightly sloping roofs. It is a relatively inexpensive way to make the roof watertight. Moreover roofing tiles are not suitable to make watertight flat roofs and bitumen roofing felt, therefore come into consideration as a possible solution.
Roofing felt is supplied in large rolls that are melted on the roof to each other and to the surface (depending on the type used). This creates the distinctive pattern of long strips on the roof.