Roofing Felt Not Necessary

Editor’s Note: In the Jan. 17 “Ask the Inspector” column, a misspelling of the roofing term “underlayment” may have confused readers. The question and correct answer are reprinted here:

Question: The home we’re buying has two layers of composition shingles, and the seller assures us that the new layer is only one year old. When the home inspector checked the roof, he found that the new shingles were installed without a layer of felt. He also found a water stain on the living room ceiling and recommended that the roof be stripped and replaced with new shingles. The seller says these water stains occurred before the new roof was installed, but the inspector believes the lack of felt is a serious roof defect. Whom should we believe? Is felt really that important, and what is roofing felt anyway?

Answer: Roofing felt is a layer of tar paper installed beneath the shingles to provide a backup waterproof membrane in case of leakage.

Felt, otherwise known as underlayment, is required when asphalt shingles are installed as a first layer of roofing or when they are applied over wood shingles or a built-up roof.

Some contractors and home inspectors believe underlayment is required when second or third layers of asphalt shingles are installed, but there is no basis for this opinion in the Uniform Building Code. In these instances, the felt beneath the older shingles is regarded as adequate.

As to the ceiling stain in the living room, this may have occurred before installing the new shingles. If you have serious doubts about the integrity of the new roof, a second opinion should be obtained from a licensed roofing contractor.

But don’t let the lack of underlayment become a major issue for you, because it is simply not required for a second layer of composition shingles.