There are two main types of chimney leaks: those that occur due to issues with the chimney itself and those that are a result of roof problems around the chimney. Roof problems are typically easy to fix once they have been properly diagnosed. A roofer will typically perform these repairs, as opposed to a chimney service.

Common Causes

The flashing is typically the source of a roof leak at the chimney. Chimney flashing is roughly shaped like an "L." Part of it sits flush to the roof surface and the other is flush to the chimney brick. Both seams are sealed down with a roofing tar or epoxy, and then shingles overlap the lower part to finalize the seal. The seals can age and crack over time, which will lead to a leak.

Damage to the flashing itself can also lead to leaks. Most flashing is made from aluminum or a similar metal. Wind can warp the flashing or weathering can lead to small holes and cracks that allow water in. Flashing can have a shorter lifespan overall compared to the rest of the roof.

Signs of a Leak

Roof leaks from around the chimney are most often noticed first inside the home. The moisture tends to flow down the sides of the chimney as it goes through the walls. It will saturate the wallboards on one or both sides of the chimney. Drywall and plaster can become soft and doughy to the touch, or the paint may begin to bubbly and peel. You may also notice water stains on the ceiling near the chimney.

External signs aren't as obvious. The shingles overlapping the flashing can begin to curl due to the moisture seeping underneath. You may also notice damage like holes or warping on the flashing itself.

Repair Options

Fortunately, chimney roof leaks are typically repairable so you won't need a completely new roof installation. For minor damages, such as failed sealant, the repair may require nothing more than putting in a new layer of tar or epoxy sealer along the flashing seams. 

More extensive damage to the flashing will mean replacing the chimney flashing with new material. Often a few shingles around the chimney will also need to be replaced due to water damage suffered when the moisture seeped in around the damaged flashing. 

Contact a roof repair service if you suspect water is leaking around your chimney.