Aside from typical problems with damaged shingles, metal roof panels, broken roof tiles, and the sort there are penetrations on your roof that need inspected. There are many types of roof penetrations on the roof and roof penetrations are the main source of water penetration through the roof. Typical roof penetrations that need inspected are, but not limited to, furnace pipes (from water heater or air handler), plumbing vent pipes, chimneys, exposed nailheads, vents, and electrical power poles. I will break down each one of the main roof penetrations:
1) Furnace pipes - These are typically made of a base flashing, collar, and double wall piping. The base flashing in integrated into the roof material, the collar is used to seal the pipe and base flashing, and the double wall pipe functions to exhaust the CO and CO2 from burning gas at the water heater or air handler. These flashings need to be sealed from the back and sides with sealants. These flashings have exposed nailheads that need caulk and the collar needs caulk to seal the base flashing.
2) Plumbing vent pipes - these are the smaller pipes connected to drains on the roof that use rubber, plastic, or lead flashings and are integrated into the roof material. The plastic and rubber flashings tend to dry rot or crack and may need replacing. The lead flashings will last the life on the roof unless you have problems with animals that might want to chew on them. The plastic and rubber flashings are by far the cheapest of these flashings and tend to have the most problems. The plastic and rubber flashings can be identified by a bulge at the base of the pipe where a lead flashing does not have a bulge at the base of the pipe. These flashings need to be sealed from the back and sides with sealants. All these flashings have exposed nailheads that need sealed.
3) Chimney flashings are described at a beginner level in a previous blog - These flashings vary depending on the type of material the chimney is made of but the typical arrangement for the chimney flashings consists of headwall, sidewall, and cricket flashings that are integrated into the roof material. An "L" flashing is in place of a cricket on older homes and not recommended if the chimney width is over 30 inches wide. The "L" flashing does not channel water away from the back of the chimney like a cricket flashing. The chimney flashings have exposed nailheads that need sealed.
4) Exposed nailheads - other than the aforementioned nailheads, there are exposed nailheads in a myriad of places on the roof material, walls, and the like that need to be sealed or they can cause roof leaks.
5) Vents - these are flashings and vents rolled into one and need to be sealed at the back and sides as well as sealing the exposed nailheads. If vents are installed improperly or in areas not recommended by the manufacturer, they can cause roof leaks and require repair.
6) Electrical Power Pole flashings - These are similar to the furnace pipe and plumbing vent pipe flashings in that the back and sides need sealed and they have exposed nailheads that need sealed. The difference in these flashings is that they are on a permanent pole and may need a special flashing if it needs replacing. Consult your roofing expert before making any changes to this flashing.
I have touched on the main roof penetrations on your roof that need to be inspected periodically. If you have not had your roof inspected in a year or so, please have this done because it can greatly extend the life of your roof.