The workmanship guarantee
This is mine. It covers the way the roof was installed: the flashings, the nailing, the underlayment laps, the valleys. If the roof leaks because of something my crew did or did not do, I come back and fix it at no charge for the term written in your contract.
It excludes damage from things nobody can control, like a tree through the roof, a wildfire, or someone else cutting into it to fit a satellite dish.
The manufacturer's product warranty
Shingle, tile, membrane and metal manufacturers warrant their material against defects for a stated period. Some extend that if the whole system, underlayment included, comes from the same maker and is installed by a contractor they have certified. I will tell you what the product you chose carries and register it where that is required.
Read the exclusions; most product warranties do not cover workmanship, which is why mine exists.
Why the inspection at the end matters
Before I sign off a re-roof, a second set of eyes walks it: every flashing, every ridge, every penetration, the eave closures on tile, the sealant on the exposed fasteners. That final check is how I can put my name on a guarantee without worrying about it.
The city inspector checks it too, but they are looking at code minimums, not at whether the counterflashing is cut in neatly.
What voids a warranty
Foot traffic from other trades is the usual culprit: solar installers, HVAC technicians, painters and satellite crews walking on tile and cracking it. Pressure washing a shingle roof strips granules. Unapproved coatings or additions can void a product warranty outright.
If someone else needs to work on the roof, let me know and I can either supervise or check it afterwards.
Warranties on repairs
Repairs carry a shorter guarantee on the specific area fixed. I cannot warrant a thirty-year-old roof against leaking somewhere else, and anyone who says they can is not being straight with you.
What I can promise is that the spot I repaired stays repaired, and that if it does not, I return.
Keeping the paperwork
You get a copy of the workmanship guarantee, the manufacturer's registration confirmation where one exists, and the final inspection photos, all in one envelope or one email. Keep them with the house documents; a buyer's inspector will ask for them, and so will an insurer after a storm.