What is Roofing Felt?
Roofing felt, also referred to as tar paper, adds an added layer of protection from the elements and is a necessary layer of your roof. It is the material sandwiched between the roof itself and the layer of roofing material below.
Most often, roofing felt protects your roof in the instance that shingles blow off your roof during a storm. It serves as a barrier between the wood sheathing and the other layers of roofing material.
Should moisture from precipitation be driven beneath the shingles, the layer of roofing felt prevents this moisture from infiltrating deeper layers of roofing material and leading to a leaky roof. It is made by soaking polyester and fiberglass fleece in a waterproofing agent.
Why is it Needed?
Roofing felt is required to construct a properly installed roof because it protects the roofing deck from rain before the roof is finished being installed.
As stated previously, it protects the other layers of the roof in case shingles are lost.
It can serve as additional protection in the case of a fire. It protects the shingles from resins in the wooden sheathing. It provides cosmetic benefit by disguising uneven segments of the roof.
Shingle manufacturers often will require that roofing felt be included in the roof as part of the warranty.
In many places, roofing felt is required to meet building code.
How is it Installed?
Roofing felt is most often sold in rolls that are 36 inches wide. It should be applied in strips at the bottom edge of the roof and worked upwards from there. Care should be taken to be sure that the paper overlaps as the felt is applied and that there are no gaps in coverage or wrinkles in the paper itself.
The felt must be smooth and have proper overlap to be certain that, should moisture work its way under the shingles, it will run down the roofing felt easily and will not drop into any of the seams on its way to the gutter.