GAF shingles must be installed on slopes of 2:12 or greater.Use minimum 3/8” (10 mm) plywood or OSB decking as recommended by APA-The Engineered Wood Assn.
Wood decks must be well-seasoned and supported, having a maximum 1/8” (3 mm) spacing using a minimum nominal 1” (25 mm) thick lumber and a maximum 6”(152 mm) width, having the adequate nail-holding capacity and a smooth surface.
Do NOT fasten shingles directly to insulation or insulated deck unless authorized in writing by GAF. Roof decks and existing surfacing material must be dry prior to the installation of shingles.
Underlayment is required by many code bodies and is required to maintain the shingles’ UL Class A fire rating. When using FeltBuster High-Traction Synthetic Roofing Felt as underlayment, it MUST be installed over one layer of VersaShield Fire-Resistant Roof Deck Protection in order to maintain a Class A fire rating for GAF asphalt shingles.
Use only zinc-coated steel or aluminum, 10 – 12 gauge, barbed, deformed, or smooth shank roofing nails with heads 3/8” (10 mm) to 7/16” (12 mm) in diameter.
Fasteners should be long enough to penetrate at least 3/4” (19 mm) into wood decks or just through the plywood decks. Fasteners must be driven flush with the surface of the shingle.
Overdriving will damage the shingle. Raised fasteners will interfere with the sealing of the shingles and can back out. Plastic film strips are present either on the back or face of each shingle.
The film strips are to prevent shingles from sticking together while in the bundle. Do not remove the film strip before or during the installation.
Use asphalt plastic cement conforming to ASTM D4586 Type I or II. These shingle have a special thermal sealant that bonds the shingles together after installation when exposed to sun and warm temperatures.
If shingles are damaged by winds before sealing or are not exposed to adequate surface temperatures, or if the self-sealant gets dirty, the shingles may never seal. Failure to seal under these circumstances results from the nature of self-sealing shingles, and is not a manufacturing defect.
If shingles are to be applied during PROLONGED COLD periods or in areas where airborne dust or sand can be expected before sealing occurs, the shingles MUST be hand sealed.
See Nailing Instructions/Hand Sealing. Proper underdeck ventilation is essential to reduce moisture build up and prevent mold. Ventilation must be designed to meet or exceed current F.H.A., H.U.D., or local code minimum requirements. For more information on ventilation requirements, see gaf.com.