5 Common Reasons For Moisture In A Chimney

Water in your chimney is a problem that should never be ignored. It indicates that something is wrong with the chimney itself or with the nearby roofing structure. The problem can quickly progress to the point of major damage and expensive repairs, as well as dangerous mold growth, if it isn't addressed quickly.

1. Crown and Cap Issues

The top part of the chimney consists of the concrete crown and the chimney cap. A crack can form in the crown as it ages, which will only get larger due to thermal pressures and moisture. Water can then seep into the crack and down the chimney. Caps can be knocked askew or blown off completely, which will leave the chimney crown and opening exposed to the elements. Replacing the crown or the cap solves the problem.

2. Cracked Bricks

Cracks in the bricks that make up your chimney are more than just a cosmetic issue. Water will seep into these cracks, slowly making its way into the chimney via capillary action. Over time, the cracks will get bigger, especially if the water inside expands during freezing weather. Not only does this lead to water in the chimney, but it can also weaken the chimney to the point of possible collapse.

3. Crumbling Mortar

Another issue that causes water issues and can lead to collapse is crumbling mortar. The mortar that seals the bricks together isn't quite as tough as the bricks, so over time the mortar may begin to crumble as it ages. At the first sign of crumbling, it's a good idea to schedule a mortar replacement. This will rejuvenate the chimney and limit the chances of a leak.

4. Peeling Flashing

Flashing is typically made of thin metal. It creates a waterproof seal around the seam between your roofing shingles and the chimney. If the flashing fails, water seeps into this seam and begins leaking into your home around the chimney protrusion. Replacing the flashing and seals is the only way to stop this type of leak.

5. Severe Condensation

Condensation is more common in gas fireplaces, as the combustion of the gas leads to moisture production. It can also happen in wood burning fireplaces if you burn damp or green wood often. Your chimney service can check the chimney for proper ventilation and improve ventilation if needed. They may also advise installing a metal chimney liner to cut down on the amount of moisture that is absorbed by a brick or clay liner.

Contact a residential chimney repair service if you suspect a leak.