Having a roof leak is not a lot of fun and can be very expensive to fix. One way to prevent roof leaks is to regularly have your roof checked by a roofing professional. This helps to catch the leaks before they get to become bigger leaks.
Algae and Mold/Ice Dams

Algae and mold being seen on your roof could indicate a problem. This happens most often in warmer and more humid climates, such as the southeastern portion of the United States and presents as black stains. Ice dams are the issue in most of the colder climates. These can happen in as little as an inch or two of snow. If your roof is leaking when the warmer days of winter hit, this is probably the problem.

Buckling Shingles 

This may be caused by a variety of reasons, such as improperly applied felt or movement of the roof deck. This, as well as other single oddities, are a good indicator of a roof leak.Curling ShinglesMay be caused by water absorption or hot air in the attic. Ineffective in protecting against leaks. You will probably need to reshingle, as this also indicates aging shingles.

Damaged Flashing

If your roof is new, it may have just been improperly done. But in older roofs damaged flashing is caused by drying and cracking. This can sometimes be repaired without replacing the entire roof. If you see water spots on exterior walls, this is a good indicator that the flashing is damaged and needs to be repaired or replaced.

Granule Loss

This indicates that you need to replace your roof. Some granules will come loose on new roofs. On older roofs, this indicates that your shingles are nearing the end of their lifespan or they are otherwise deteriorating. The shingles may even have bald spots in extreme cases, otherwise, they will just look exposed.

Lack of Attic Ventilation

This will cause your roof shingles to bake from the trapped hot air in your attic. The heat will cause your shingles to age faster and start to curl.

Missing Shingles

These are generally caused by storms and high winds, and generally, indicate that the shingles were not put on correctly or that the sealant strip is damaged. It can also be caused by critters getting onto your roof. Missing shingles have to be replaced to maintain the integrity of the roof.

Roof Rot

This is more common with organic-based shingles. Indicates water absorption into the mat. This means your roof needs to be replaced.

Ceiling Or Roof Spots

This indicates that water is already getting into your home. You will see water stains on your ceilings or roofs. Leaks are commonly spotted around chimneys and vents. Leaks are also known to travel down the rafters and show up quite far from the original source. It can also travel down anything you have in your attic as well. While there are other reasons for ceiling spots to occur, if they show up after a good rain you may have a problem on your hands.Finding the source of leaks can be very hard to do, which is why it is recommended to have a roofing contractor inspect your roof regularly. No one wants to completely have their roof redone as it is expensive.