Roofing materials
Roofing material is the outermost layer on the roof of a building, sometimes self-supporting, but generally supported by an underlying structure. A building's roofing material provides shelter from the natural elements. The outer layer of a roof shows great variation dependent upon availability of material, and the nature of the supporting structure. Those types of roofing material which are commercially available range from natural products such as thatch and slate to commercially produced products such as tiles and polycarbonate sheeting. Roofing materials may be placed on top of a secondary water-resistant material called underlayment.
The weatherproofing material is the topmost or outermost layer, exposed to the weather. Many materials have been used as weatherproofing material:
Reed thatch on the island of Sylt
Slate, England
A church roof under repair with terracotta tiles
Bitumen, United States
Corrugated iron, Australia
Sheet metal roof
PVC roof
Air-supported polyester roof, Michigan, USA
Copper clad roof, MIT, United States
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