What is underlayment felt paper and why use it?
A. Underlayment felt paper is an asphalt-saturated felt installed between the roof deck and the roof shingles. Underlayment is primarily used to separate the roof shingles from the roof deck. It helps to shed water during shingle installation, helps in meeting Class A and Class C shingle fire ratings, helps protect from resins that may come from wood board sheathing, helps prevent “picture framing” which is the visible outline of deck panels, cause by roof irregularities in the decking thickness, provides secondary weather protection during a wind-driven rain storm and in some cases protects your home when your shingles are blown off during a storm.
