[Answer] [misc.consumers.house] [Newsgroups]
Most likely they used two layers of 15# felt. (actually it's required inof
Ohio because for ice protection at the eaves.) The felt is double layered
and cemented together up to a point 24in. in from the exterior walls. If
the roof slope is 2:12 up to 4:12 (low-slope) a double layer is still
required for the rest of the roof (otherwise 15# will be code).
About the only way you can tell is to look under the shingles at the edge
the roof. You may be ably to see if it's one or two layers. (Look about
mid-roof).
News-Portal was written by Florian Amrhein.