[dieseldawg142]

actually when you get your roof done, there is 2 warranty's. one from the shingle manufactor for material defects or shingle failures, and one from your roofer for workmanship.
almost all shingle brands warranty over top...but be aware, 9 1/2 times out of 10 they will claim improper installation if a prob arises, which sadly in my experiance, is true.
like i said, water has very narrow shoulders, it WILL find poor work.
here's an excerpt from GAF shingles;

"The GAFMC Smart Choice limited warranty provides coverage against inherent manufacturing defects in the shingles regardless of their application. Even if your roofing system was not properly installed in accordance with GAFMC's application instructions, the limited warranty will remain in effect against manufacturing defects.
However, the warranty does not cover any damages to the shingles or roofing system resulting from anything other than an inherent manufacturing defect.
It is a standard roofing practice to install shingles over the top of existing shingles. The limited warranty on the shingles affords the exact same coverage for a single or multi layer.
If you have any concerns or questions regarding the application of your roofing system, please contact our Technical services hotline at 1-800-766-3411.
Thank you for choosing GAFMC products, we appreciate your business."

but further into their warranty....

"GAF's studies indicate that more than two-thirds of the problems that people experience with their new roofs are due to the contractor's workmanship, not the roofing materials. This is an important distinction to keep in mind when deciding on warranty coverage."

like i say, unless your a ticketed roofer or are an authorized installer (meaning you took that shingle manufactor's courses on how they want them installed) they will quite often push claims into the workmanship catagory.
we give out between a 5 to 10 yr warranty on our workmanship depending on what the owner decides. if you have a workmanship prob, 99% of the time it will show up within a few yrs, still in your warranty timeframe. and in this business, your reputation is EVERYTHING. nobody ever remembers a good job, but everyone will remember a poor job...