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G.A.P. 15# Asphalt Felt Roofing Underlayment, ASTM D226, 4 Squares per Roll
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G.A.P. 15# Asphalt Felt Roofing Underlayment, ASTM D226, 4 Squares per Roll
G.A.P. 15# Felt is an organic asphalt-saturated felt underlayment applied over the roof deck before asphalt shingles are installed. Each roll covers approximately 4 squares and meets ASTM D226. It is recommended for use under 20-year asphalt shingles.
Key Features:
- Deck Protection: Applied over the roofing deck before shingle installation to provide a secondary layer of protection under asphalt shingles.
- ASTM D226: Manufactured to meet ASTM D226, the standard specification for asphalt-saturated organic felt underlayment.
- 4 Squares per Roll: Each roll is sized at 4 squares, covering roughly 400 sq. ft. of roof deck.
- Shingle Pairing: Recommended for use with 20-year asphalt shingles.
- Proven Material: Traditional 15-pound felt remains a widely used, economical underlayment choice for residential roofing.
Specifications Table:
| Specification | Details |
|---|---|
| Brand | G.A.P. |
| Sell unit | 1 roll, 4 squares |
| Product line | G.A.P. Felt 15# |
| Material | Asphalt-saturated organic felt |
| Nominal size | 15# (15-pound) felt |
| Coverage per unit | 4 squares per roll (approx. 400 sq. ft.) |
| Approvals | ASTM D226 |
| Dimensions | 4 Square/Roll |
| Intended use | Underlayment beneath asphalt shingles on residential roofs |
| Available sizes | 4 Square/Roll |
Coverage & How Much You Need:
One roll covers 4 squares, or about 400 sq. ft. of roof deck. Estimate rolls by dividing total roof area in squares by 4 and adding extra for laps at eaves, ridges and overlaps.
Fit and Compatibility:
Designed for use under asphalt shingles, particularly 20-year grade shingles, and is installed over the roof deck prior to shingle application. Shingles, fasteners and drip edge are sold separately.
Frequently Asked Questions (FAQ):
Q: What is included with one order?
A: One roll of G.A.P. 15# felt underlayment, sized at 4 squares per roll and meeting ASTM D226.
Q: How much area does a roll cover?
A: Each roll covers approximately 4 squares (400 sq. ft.) of roof deck; plan for overlap at laps when estimating.
Q: When is this felt installed?
A: It is applied over the roofing deck before installation of asphalt shingles.
Q: Is it rated to a standard?
A: Yes, this felt is produced to ASTM D226.
Q: What shingles does it pair with?
A: It is recommended for use with 20-year asphalt shingles.
Expert Verdict — Reviewed by the SuperArbor Pro Desk
Fifteen-pound felt is the workhorse underlayment for standard-duration asphalt shingle roofs. Deck it out dry and lap horizontal courses at least 2 in. with 4 in. at end laps, and install it the same day you shingle where possible to limit exposure. For premium or long-duration shingle systems, consider a synthetic underlayment instead.
Felt underlayment becomes slippery, especially when wet or dusty — wear fall protection and appropriate footwear when working on the roof.
Order G.A.P. 15# Felt Underlayment today and give your shingle roof a proven deck-level layer of protection.
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