GAF Silicone Mastic Sealant, White (3.5 Gal)

Professional-grade, thick silicone mastic designed for flashing and detail work. Low-odor, fast moisture-cure formula adheres strongly to a wide range of roofing substrates.

Key Features:

• High-Build Silicone Sealant: Thick consistency for robust coverage on seams, penetrations, and flashing details
• Easy Application: Low odor and smooth tooling help speed installs on the jobsite
• Fast Moisture Cure: Cures quickly to reduce downtime and return roofs to service faster
• Strong Multi-Surface Adhesion: Formulated to bond to a variety of common roofing substrates
• Tested Performance: Meets ASTM D1644, D2697, and D2370 standards

Specifications Table:

Frequently Asked Questions (FAQ):

Q: What is the color of this silicone mastic?
A: White.

Q: How much product is in the container?
A: 3.5-gallon pail.

Q: What standards does it meet?
A: ASTM D1644, ASTM D2697, and ASTM D2370.

Q: Where is it typically used?
A: For flashing, seams, penetrations, and detail repairs on compatible roofing systems.

Q: Does it have strong odor?
A: No—it's a low-odor formula for easier application.

Sculpted Protection with a Clean, Architectural Finish

This silicone mastic draws a crisp, modern line around roof penetrations and edges, bringing order and polish to functional details. I love the dense, high-build body—it lays down with confidence and dries into a sleek, resilient skin. Use it to frame flashing and seams with a refined, white accent that feels intentional. It’s a quiet essential—performance-forward and luxuriously reliable.

Seal critical roof details with confidence—choose this GAF Silicone Mastic for fast-curing, durable adhesion that lasts.