Every year, GAF trains and certifies thousands of roofers in high-quality installation methods using the latest technologies. Our criteria require all roofing companies to provide proof of government license (if required) and insurance, and prove that they have a good reputation with the Better Business Bureau. GAF Factory certified contractors can offer a variety of GAF-backed extended warranties, so you can choose the right contractor and level of coverage for your project.* If you choose a GAF Timberline roof® for your repair or replacement, you`re in good company. More Americans have relied on GAF Timberline® shingles than any other brand. With more than a century of experience and know-how, GAF has the products, technologies and solutions adapted to your roofing needs. .