Roof materials
Different roof materials and how much rainwater they can collect.
Asphalt shingle
Asphalt shingle can collect about 85% of the precipitation.
Sheet metal
Sheet metal roofs can collect about 90% of the precipitation.
Clay and concrete tile
Clay and concrete tile roofs can collect about 80% of the precipitation.
Slate
Slate roofs can collect about 90% of the precipitation.
Wood shake
Wood shake can collect about 70% of the precipitation.
Roofing felt / bitumen
Roofing felt and bitumen roofs can collect about 80% of the precipitation.