Do I need tar paper under my asphalt shingles? AskARoofer was asked this question a while back by a woman and this question comes up very often.
It seems this lady’s house was recently purchased and after the first few spots of winter rain came, the owner developed a leak near a chimney. The owner called the roofer that did the certification and he said after an inspection, “It needed a chimney flashing and was not covered under the warranty” and suggested a sheet metal professional come out and install completely new flashing.
So the new homeowner hired another roofer to get a second opinion. As you can see on the above photo, the chimney appears to not have a lower saddle (chimney flashing) but what is concerning to the second contractor was the lack of any tar paper under the shingles. So, the question was asked. I have seen roofers lay the asphalt shingles directly to the wood deck. I personally always used tar paper or underlayment with an asphalt shingle roofing system. To me it just seems a bit strange not to because of it’s great value to the roofing system. I guess the best questions to ask are – What does your building department require? What does the shingle manufacture require to maintain a factory warranty?
Climate zones will have a lot to do with a contractor using underlayment or not. In heavy snow zones, you need some type of underlayment to be installed whether it's tar paper, felt or synthetic, and even ice shield to protect against ice dams.
Underlayments provide several benefits when used. They can be used to weather-in a roof for a temporary roof covering, while the roof is being installed. If there is a problem that comes up with the asphalt shingles, then having the underlayment as the last stand is very comforting to a homeowner. High winds can cause wind-driven rain to seek out entry into the attic and having this added protection can avoid damaging moisture intrusion. Over the years, even the resins from the wood can have a negative effect on the asphalt. Divorcing the two materials with tar paper resolves this issue. Most important to me, as a contractor, is that it's required by the manufacturers to have felt to have a factory warranty. The cost of using tar paper versus not using tar paper under your shingles is not that much for an average house, and well worth your money.
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