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*

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 toughness1.

Products in the HydroStop® System

HydroStop® System Case Studies

Real life roof coatings projects using the GAF Premium Acrylic HydroStop® system

5 simple steps to metal roof restoration

with the HydroStop® System

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

2. Prime rusty areas
• Treat rusty areas with GAF Metal Roof Primer1

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 Flashing2

• Fasteners: Encapsulate all fasteners using GAF Premium Brush-Grade Flashing

4. Detail penetrations
• Treat all curbs, penetrations, and drains with GAF Premium Brush-Grade Acrylic Flashing and 12” GAF Premium Fabric

• Three-course at a rate of 30 linear feet per gallon

5. Coat the roof
• Apply two coats of GAF Premium Acrylic HydroStop® Top Coat per the specifications for a 10/15/20-year limited warranty or guarantee

• GAF acrylic can be brushed, rolled, or spray-applied

• Option for additional surface coating with GAF Kymax Coating

Additional Resources

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


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

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Call us at 1-855-478-5041 or email us below


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