For a roofer to have this certification, they must have been providing superior roofing services for close to 10 years, with state and local licenses to show for it. They must also be known for reputable business practices, including a satisfactory rating from the Better Business Bureau® (BBB). They should be adequately insured, carrying workers’ compensation and general liability insurance. Lastly, they should commit to ongoing training on GAF’s new products and standards.