Roofing felt, or felt paper, is a type of protective barrier roofers will put between shingles and your home's roof deck. While there is fairly wide acceptance of this form of roof protection, there are several theories that suggest this felt paper is unnecessary and at times even harmful for a roof. Here is how this roofing underlayment works and whether it is right for your home.
Uses of felt paper on a roof
In many instances, workers replacing a roof will use felt paper as a protective barrier before installing shingles on a roof. This coating serves as protection against moisture and may upgrade the fire resistance of a roof if left in place. If there were a leak coming from the roof, felt paper would be able to trap moisture before it moved inside your home. Manufacturer warranties and building codes may even call for felt paper to be installed on a roof under the shingles.
Still, moisture protection is only possible when the roofing felt is whole, which is unlikely when shingles are nailed into the roofing deck below. For this reason, some inspectors and roofing professionals are skeptical about the essential nature of felt paper. Chances are a professional roof installation would be fine without the use of felt paper if other measures were taken, though any job would be safer for roofers if felt paper were part of the project.
Issues with overheated roofs
The same issues that arise with overheated roofs could come up with the use of felt paper as roof underlayment in the Atlanta area. Roofing felt may serve to trap heat between the roof deck and shingles, which will decrease the life span of a roof and limit the value of your investment in a new roof. Protection from the elements is always a good thing with a roof, but creating another problem (a way of trapping heat in the roof) would have an overall negative impact on your home.
Roofers that offer to help save you money by installing a second layer of shingles over an existing layer will create the same problem for your home. Besides putting off the work of removing shingles until a later date, the second layer of shingles traps heat on your roof and may void the warranty for new shingles. Fixing leaks could be more problematic with multiple layers of shingles as well.
While roofing felt paper may be a practical solution during shingle installation or other roofing projects, it is unlikely you need this product for functional purposes. Ask a roofing professional about the best solution for your particular home during the next inspection.