Multi-Purpose Primer

Effective at increasing the bond of: 

  • acrylic 
  • polyure- thane 
  • butyl 
  • silicone 

Coats over most new or existing roof, deck, and wall substrates, as well as existing coatings.


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GAF Multi-Purpose Primer is a two-component, water-based epoxy, 9 to 1 ratio primer. It is effective at increasing the adhesion of acrylic, polyurethane, butyl, and silicone coats over most new or existing roof, deck, and wall substrates, as well as existing coatings. GAF Multi-Purpose Primer is easy to use and clean up.


Concrete, asphaltic, aged single-ply membranes, and existing coatings. It can also be used on non-ferrous metals, galvanized, aluminum, galvalume, and coated (including Kynar) steel.


1-gallon kit Part A: 0.9-gallon (3.41 liter) can Part B: 0.1-gallon (0.38 liter) can 5-gallon kit Part A: 4.5-gallon (17 liter) pail Part B: 0.5-gallon (1.89 liter) can


PRODUCT STORAGE TEMPERATURE: 50°F - 90°F (10°C and 32°C). Do not open containers until ready to use the material. Do NOT allow the product to freeze. SHELF LIFE: 12 months if unopened containers, if stored properly


Roof must have positive drainage and be clean and dry with no trapped moisture. Repair damaged membrane, flashings, and penetrations. See Liquid-Applied Roofing Manual at


GAF Multi-Purpose Primer is a two-component material. Mix Part A individually, then add Part B into Part A and mix until a uniform consistency is achieved. Once mixed, the usable pot life is approximately 2 hours at 75°F (24° C). Do not use any material that has been mixed for more than 4 hours. Avoid overmixing, as product will thicken.


GAF Multi-Purpose Primer may be applied by brush, roller, or spray at the rates specified to the right. Call GAF Technical Support Services for spray recommendations. GAF Multi-Purpose Primer is not designed to form a heavy surface film. Over-application will reduce adhesion strength. Allow primer to dry. Primer MUST be top-coated within 48 hours of application or the top coat will not achieve a chemical bond with the Multi-Purpose Primer.