FlashSeal Elastomeric Flashing Sealant 1 Gallon - LongLasting Leak

Our review of FlashSeal Elastomeric Flashing Sealant finds it best for homeowners and roofers who need a durable, flexible fix for leaks at chimneys, stacks, vents, and skylights; the single biggest reason to buy is that it forms a waterproof, permanently flexible membrane that bonds to shingles, metal, and brick for long-lived repairs. It is presented as a practical alternative to tar-based patching, with soap and water cleanup and a 1 gallon size that covers about 28 sq. ft., making it a sensible choice when a custom-fit flashing boot is required without a full roof replacement.

Key Features

• 7 Year Warranty: Provides peace of mind when used with FlashSeal Fabric, covering the product for long-term performance.
• Flexible Waterproof Membrane: Dries to a flexible, watertight layer that accommodates thermal movement and settles without cracking.
• Broad Adhesion: Bonds permanently to asphalt shingles, metal flashings, brick, and common roofing materials for versatile repairs.
• Easy Application: Applied with a brush for targeted repairs around chimneys, vents, stacks, and skylights, making installation straightforward for pros and experienced DIYers.
• Clean Cleanup: Soap and water cleanup removes uncured material, avoiding strong solvents and simplifying jobsite cleanup.
• Coverage: One gallon covers approximately 28 sq. ft., allowing estimation of quantity for typical chimney and flashing repairs.

Who It's For

FlashSeal is aimed at homeowners dealing with recurring leaks around chimney bases, roof penetrations, and skylights who want a permanent, flexible repair without resorting to tar or full flashing replacement. Roofing contractors and maintenance professionals will value the product for its adhesion to multiple materials and the 7 year warranty when paired with reinforcement fabric.

It is less suitable for those who need a complete roofing overhaul or for users expecting an all-in-one kit, since the product is sold separately from FlashSeal Reinforcement Fabric and the application brush is not included. Novices should be comfortable with roof work or hire a professional for safe, effective installation.

Pros & Cons

Pros

• Creates a durable, flexible membrane that resists cracking and outlasts tar-based sealers.
• Adheres to a wide range of roofing materials, making it useful for many flashing issues.
• Soap and water cleanup is convenient and safer than solvent-based alternatives.

Cons

• Brush is not included, and reinforcement fabric is required to qualify for the 7 year warranty, adding cost and planning.

Specifications

Product	FlashSeal Elastomeric Flashing Sealant
Size	1 gallon
Coverage	Approx. 28 sq. ft. per gallon
Suitable Substrates	Asphalt shingles, metal flashings, brick, roof materials
Cleanup	Soap and water
Application	Brush application (brush not included)
Warranty	7 year when used with FlashSeal Reinforcement Fabric

Our Verdict

FlashSeal is a practical, cost-effective choice for repairing leaks at chimney bases, skylights, and other flashings because it bonds to common roofing materials and remains flexible over time. For homeowners and contractors seeking a long-lasting flash repair that avoids tar, it offers good value when paired with the recommended reinforcement fabric.

Frequently Asked Questions

Does this product require reinforcement fabric to work?
It will form a flexible waterproof membrane on its own, but the 7 year warranty applies only when used with FlashSeal Reinforcement Fabric sold separately.

What surfaces will FlashSeal adhere to?
It is formulated to adhere to asphalt shingles, metal flashings, brick, and typical chimney and roofing materials.

How do you clean up after application?
Uncured material cleans up with soap and water, so no strong solvents are required for cleanup.