Liquid Rubber Waterproof Sealant for Flat & Low Slope Roofs - 5 Gallon

In this review the Liquid Rubber Waterproof Sealant is presented as a practical solution for homeowners and contractors who need a flexible, long-lasting barrier against leaks. The bottom line: if you want a water-based, low-odor alternative to roof tar that bonds to metal, concrete and most building substrates, this product delivers a robust waterproof membrane and professional coverage when applied properly. It is especially useful for patching RV roofs, chimneys, gutters and low slope roofs where elasticity and adhesion matter most.

Key Features

• Industrial strength bitumen formula: Forms a seamless waterproof membrane that resists water infiltration on flat roofs, gutters, foundations and concrete surfaces.
• Superior flexibility: With high elongation the coating maintains adhesion through building movement and temperature swings to reduce cracking and peeling.
• Professional coverage: Brush, roll or spray application provides clear coverage guidelines so installers can build a 30-80 mil membrane depending on surface and coats.
• Water-based advanced formula: Low-odor, no VOCs and safe for use near foam insulation and in confined spaces where solvent products are impractical.
• Engineered waterproofing system: Works with seam tape or geo-textile to bridge joints, vents and skylights for a comprehensive leak repair approach.

Who It's For

The product suits homeowners, property managers and contractors tackling roof leak fixes, basement and foundation waterproofing, or repairs around chimneys and RV roofs. Its water-based, low-odor formula makes it a good fit for projects where solvent fumes are a concern and for DIYers comfortable with multiple coats and surface preparation.

Those who need a walkable surface, a decorative topcoat, or a ready-made patch for heavy foot traffic should look elsewhere, because this coating can remain tacky after curing and is not rated for reliable pedestrian wear like decks or patios.

Pros & Cons

Pros

• Creates a durable, flexible rubberized membrane that adheres to metal, concrete and wood.
• Water-based, low-odor formula that cleans up with water and is safer around foam insulation.
• Clear professional guidance for coverage per gallon and multiple application methods: brush, roll or spray.

Cons

• Can remain tacky after curing and is not suitable for regular foot traffic surfaces.
• Some users report adhesion issues in a few cases, so proper surface prep and optional seam tape are important.

Specifications

Our Verdict

The Liquid Rubber Waterproof Sealant is a solid value for projects that require a flexible, industrial-strength membrane without solvent fumes. Pros and DIYers who apply the recommended multiple heavy coats and use seam tape where needed will get long-lasting protection on low slope roofs, foundations and metal surfaces. Avoid for high-traffic surfaces, but for leak repair and preventative waterproofing it offers professional-grade performance at a practical price.

Frequently Asked Questions

Can this be applied over existing roof tar?
Yes, it can be applied over many existing bitumen surfaces after cleaning and ensuring good adhesion, but test a small area first.

Is it safe for foam insulation?
Yes, the water-based formula does not harm foam insulation and is suitable for confined spaces.

How many coats are needed for a reliable membrane?
For flat roofs aim for 3-4 heavy coats to achieve a 60-80 mil membrane; vertical surfaces typically need 2-3 heavy coats for a 30 mil membrane.