I got a couple of quotes today for an architectural grade composition roof (40 year). Both quotes spec’ed 15# felt as underlayment. I have always understood 30# felt to be standard for roofs. By the way, I am not a roofer. Both quotes came from well regarded companies, not fly by night (at least not by reputation). Location is Seattle, FWIW. What do the roofers out there recommend? Is there a recent change in the quality/durability, is there a “new improved” 15# felt out there?
Thanks for the input
Brad
Replies
I read a great article recently that explained that there are 3 grades of "15# felt":
* material that has no ASTM rating
* material that meets ASTM D 4869 (weighs at least 8lb/100sf)
* material that meets ASTM D 226 (weighs at least 11.5lb/100sf)
"30# felt" comes as:
* ungraded (16 to 20lb/100sf)
* ASTM D 226 (26 to 27lb/100sf)
Hope this helps.
You might look into using one of the newer underlayments, like Triflex or RooftopGard....comes in 10 sq. rolls. A roll weighs about the same as a roll of felt, but it's tough, lays flat, doesn't wrinkle if it sits exposed for a few days.
But to answer your original question, #15 will do, though I think most of us use the heavier #30 if given a choice. 15# and 30# are hard to find off the shelf anymore.