GAF Certified means the roofer is factory-certified by GAF, North America's largest roofing manufacturer, and can offer GAF's enhanced System Plus Limited Warranty on qualifying GAF roof systems.
Why it matters to you
Any roofer can buy GAF shingles. A GAF Certified contractor has met GAF's requirements and can register qualifying roofs for an enhanced warranty that goes beyond the standard product warranty.
How to check
GAF lists certified contractors on its website. You can see MDJ Roofing and Construction's GAF listing here.
Ask about the warranty in writing
Before you sign, ask which warranty your roof will get and what it covers. A good contractor puts that in the quote.