Your roof may seem incredibly durable with all it is able to withstand over the years, but it won't last indefinitely. There will come a time where the roof needs to be repaired due to wear and tear over the years. These are a few of those problems that it will help to have a certified roofer do the repairs for you to ensure that they are done right.
A roof will leak when there is a part of the roofing material that has cracked and allows water to get underneath the surface. Leaks can start small, but end up growing bigger over time due to neglect and noticing the damage that it is causing. You may notice a part of your ceiling is slowly getting darker due to water damage, or that you start to smell mold in your home.
A roofer needs to investigate this problem to find out how deep the damage goes. Is it only a matter of replacing some of your roofing material, or has the water caused significant damage to your roof deck? A simple repair may eventually turn into roof replacement if a large portion of your roof needs to be removed to fix the underlying problem with your roof deck.
It can be difficult to fix shingles on your own for a couple of reasons. Not only do you likely not have the knowledge of how to do the repair correctly, but there is the logistics of finding shingle material that doesn't stick out on your roof like a sore thumb. If you do not have extra shingles lying around that can be used for roof replacement, you'll need to find the necessary roofing material to make the repair.
This is where a certified roofer comes in. They will have the resources to track down similar looking roofing material so that the roof replacement looks great when it is finished. This is something you may struggle with, especially when you feel limited to the roofing material that you can buy at your local home improvement store.
The water may be getting underneath your shingles due to flashing that has become damaged over the years. The flashing is essentially pieces of metal that go over edges of the roofing material, and prevent water from getting underneath the shingles. It is used around anything that sticks out from a roof, such as a skylight or ventilation pipe. All of the flashing needs to be inspected for damage, replaced if it is damaged, or reattached if it is no longer forming a tight seal to your roof.