Roofing felt is a vital part of roofing for houses with pitched roofs. It sits below the actual roof tiles themselves and above the rafters. Roofing felt is important because it provides the actual waterproofing of the roof. The material repels water that penetrates the roof tiles. However, there is a limit to the amount of water that certain types of felt can repel, so it tends to not work on houses with flat or very low pitched roofs.
Roofing felt is particularly useful because of its versatility. In a pinch, if the roof tiles are damaged and a gap is opened roofing felt can still maintain the waterproofing of the house temporarily. A variation of roofing felt called shed felt can be used as the main outer layer for structures like outhouses or sheds.
What are the different types of roofing felt?
There are several different varieties of roofing felt. One is called Breather Membranes are very permeable, and can aid in the ventilation of the roof. However, breather membranes should still be used in conjunction with roof vents as opposed to being used instead of roof vents. ERoofing stocks many brands of breather membranes including Permavent Black and Cromar Vent 3.
Then there are non-breather membranes which are impermeable. This means that they are less conducive to ventilation. Non-breather membranes are primarily used for “cold roof” houses, where the roof itself is not insulated and instead the highest ceiling is. They are less useful in standard “warm roof” houses.
Shed felt is designed to look pleasing to the eye for the top layer of a structure, as opposed to a second layer as in the other types. Shed nails are important for securing shed felt. At ERoofing, we recommend the Galvanised extra large head nails, available in either 25 mm or 20 mm.