“Standard 30# asphalt ” felt vs “ASTM 30# asphalt felt” (ASTM D-266)
I’m in a hot humid climate. Using plywood wall sheathing with 30# felt as the WRB, then a gap and then brick veneer. I was looking for a “better quality” 30# felt. The supplier tech support advised that most lumber yards stock what is referred to as “standard 30# felt” (actually ASTM 4869 at 16# per square). They also make what is referred to as “ASTM 30# asphalt felt” (actually ASTM D-226 at 26# per square). So here’s the question—-Is this D-266 similar to the 30# felt made and used decades ago, and thus better to use? My main question is the perm rating—-I’ve not been able to find that number. I don’t think it should be an issue, but I’m paranoid about accidentally putting in a vapor barrier in the wall of a hot humid climate. Any help out there would be appreciated.