When replacing a roof with new asphalt shingles, is it best to take off the layer of old felt with the old shingles? Is it better to lay new felt over the old felt before putting new shingles on? Why do some companies take off the old felt, and some leave it on?
I get this question many times and it is my opinion that the old felt should be removed and not covered over. I don’t know why some roofers say “leave it on”. I seem to me if you are going to the trouble of removing the shingles, you now have a chance to do repair on the roof deck by removing all the old felt. Dry rot can occur with leaks and now with the roof totally off it can be inspected and be repaired. This includes the framing that could be damaged. I see no value in leaving felt paper that is all ripped up, and full of nail holes. It is more effort to not remove the felt than it is tearing it off. There could be, with an aged roof, many nails in the sheathing deck that back up. With removing the felt these nails can be seen and re-driven down and thus making a nice surface for the brand new felt and shingles. The key to a good shingle installation is a prepared roof deck. Having that will promote a long life for your roof.
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Orangevale, CA 95662
Lic # 719925