Which roofing material is an organic fiber mat impregnated with asphalt and used as an underlayment?

• A. Fiber Glass Shingles
• B. Exposure
• C. Downspout
• D. Felt

Answer: (D)

Underlayment is the protective layer placed on the roof deck before the finished shingles go on. Felt fits this role because it’s an organic fiber mat (historically made from rag or cellulose) that’s impregnated with asphalt to create a water-resistant barrier. This combination provides a surface for nailing, adds a secondary layer of rain protection, and helps shed moisture if the shingle layer isn’t fully watertight yet. It’s also commonly called tar paper, and it sits beneath the shingles, not on top of them.

The other options don’t serve as underlayment. Fiber glass shingles are a type of roofing shingle, not the underlayment beneath them; “Exposure” isn’t a roofing material; a downspout is part of the drainage system. So felt is the material that matches an organic fiber mat impregnated with asphalt used as underlayment.