If your roof is over 10 years old, it is time for a thorough inspection and potentially investing in an entirely new roof altogether, especially if your roof was laid over a previously installed roof.
Next, take a flashlight with you to your attic or to the space where the interior of your roof is visible and look for signs such as beams of light, leaks, or streaks or stains on the inside of the roof.
Then move to the exterior of the roof. When inspecting the outside, be sure to look for any cracks, dents, missing or warped shingles.