When it comes to protecting the “high-traffic” water channels of a roof, standard underlayments often fall short. G.A.P. Valley Seal, distributed nationwide by A1A Wholesale Supply, is a specialized solution that combines the strength of fiberglass with the self-healing and flexible properties of SBS modified asphalt.

Unlike metal valley flashing, which can be difficult to form and prone to corrosion, or thin “peel-and-stick” products that may be hard to reposition, Valley Seal is designed for maximum “workability.” It stays flexible in cold weather and stable in high heat, ensuring it conforms perfectly to the “V” or “U” shape of a valley without buckling or puckering. Because it meets the rigorous ASTM D1970 moisture vapor permeability standards, it effectively “locks out” water while allowing the roof system to perform as intended.

Product Details

• Manufacturer: G.A.P. Roofing, Inc.

• Composition: Glass fiber reinforced core with dual layers of SBS polymer-modified bitumen.

• Thickness: 55 mils (Professional Grade).

• Roll Width: 36 inches.

• Coverage: 100 sq. ft. (1 Square) per roll.

• Weight: 36 lbs per roll.

• Logistics: 42 rolls per pallet / 30 pallets per truckload.

Features & Benefits

• SBS Modified Pliability: The polymer-modified asphalt ensures the roll remains easy to bend and shape, providing excellent conformity to roof transitions.

• Superior Debris & Water Resistance: Passes the ASTM D4869 Liquid Water Transmission test, ensuring total protection in high-volume water flow areas.

• Lay-Flat Technology: Specifically formulated to resist wrinkling and curling, saving time during installation and providing a smoother surface for shingles.

• Vapor Protection: Meets ASTM D1970 standards for moisture vapor permeability, acting as a high-performance barrier against internal and external humidity.

• Versatile Compliance: Meets or exceeds standards for ASTM D226 (Type I & II) and ASTM D4601, making it a “multi-tool” for various roofing specifications.

• Ease of Use: Significantly easier to cut, fit, and install than traditional metal valley liners.

Applications

• Valley Lining: The primary choice for waterproofing open or closed valleys in asphalt shingle systems.

• Roof-to-Wall Transitions: Ideal for providing a reinforced moisture barrier at vertical intersections.

• Eave & Gable Protection: Provides extra-thick defense against wind-driven rain at the roof’s perimeter.

• Critical Flashings: Used around chimneys, skylights, and large vents where extra thickness and flexibility are required.

Technical Specifications & Logistics