Contractor spraying Hydrostop on roof

Premium Acrylic HydroStop® System

The HydroStop® roof coating system is an affordable solution to extend the life of structurally sound metal roofs.

A fully-reinforced roof coating system assembly that meets FM 4470*

Components of Hydrostop system

Count on the HydroStop® System for recover, reroof, and new roof applications.

This easy-to-apply roof system offers excellent adhesion to a variety of substrates, including metal, structural concrete, TPO, PVC, Hypalon®, EPDM, polyiso, gypsum roof board, and asphaltic roofs, for a combination of reinforcement and toughness.
*Refer to FM RoofNav for Actual assemblies

Products in the HydroStop® System

See all roof coating solutions
Premium Acrylic Hydrostop Top Coat

GAF Premium Acrylic HydroStop® Top Coat

A professional grade, water-based, acrylic elastomeric coating that is part of the GAF Premium Acrylic HydroStop® Coating System. Get documents
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Premium Acrylic Hydrostop Base Coat

GAF Premium Acrylic HydroStop® Base Coat

A water-based acrylic base coat. Used in conjunction with the Premium Acrylic HydroStop® Top Coat and the Premium Fabric, it creates the GAF Premium Acrylic HydroStop® System. Get documents
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Learn about warranty and guarantee coverage

Warranty info

HydroStop® System Case Studies

Aerial view of Shoe Show, Inc. Distribution Center

Shoe Show, Inc. Distribution Center

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Aerial view of Texas A & M University with new GAF roof coatings

Texas A&M University

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Front view of the Alamo Shrine with new GAF roof coatings

The Alamo Shrine

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5 simple steps to metal roof restoration

with the HydroStop® System
Contractors preparing roof for coatings

1. Qualify and prep the roof

  • Ensure the roof is clean, dry, and tight
  • Conduct adhesion test to ensure proper coating adhesion
  • Make any necessary repairs to the sheet metal and secure or replace all loose or missing fasteners
  • Power wash roof using GAF Cleaning Concentrate
  • Install sheet metal crickets behind rooftop units, if needed
Contractor priming rusty areas of metal roof

2. Prime rusty areas

Roofing contractor treating seams

3. Treat seams and fasteners

  • Seal horizontal seams, ridges and rake edges using a roof brush with GAF Premium Brush-Grade Acrylic Flashing and 12” GAF Premium Fabric (Three-course at a rate of 30 linear feet per gallon)
  • Vertical seams: Seal with GAF Premium Brush-Grade Acrylic Flashing
  • Fasteners: Encapsulate all fasteners using GAF Premium Brush-Grade Flashing
Roof contractor detailing penetrations

4. Detail penetrations

Apply GAF Acrylic Base Coat to help improve adhesion of the GAF Acrylic Top Coat and mitigate any asphaltic bleed-through- Apply Acrylic Base Coat per the specifications for a 10/15 year warranty, can be brushed, rolled, or spray-applied
Roofing contractor coating roof with HydroStop

5. Coat the roof

Download the complete installation steps

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Additional Resources

Use these links to connect with the products and people you need to get the job done.

Roofing supply near me

Find distributors that carry GAF low-slope products and systems.
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Coatings support

Call us at 1-855-478-5041 or email us below
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Building a better GAF Commercial around you

Contractors

We’re building new plants for greater capacity, and better systems for faster response and higher visibility.
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Architects

We’re building better, faster, more accurate access to the information you need.
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Property Owners

Whether you manage one property or 1,000, we’re building the products and programs you need to reroof, restore, or maintain your investment.
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We’re building a better GAF Commercial around you

We’re building a better GAF Commercial around you, with more manufacturing capacity, dedicated teams, more focused training, optimized product lines and more — because you have options, and we’re ready to earn your order.