A leak in the chimney can cause major issues inside your home, including a heightened risk of a chimney fire or dangerous gasses leaking into your living spaces. Leaks can be caused by age, outside damages such as from shifting ground, or from cracks in the chimney or liner. Know the signs of a leak so you can have the problem repaired before it becomes a danger.

1. Firebox Moisture

Your firebox, the part of the fireplace where you place the wood, should never show any signs of moisture. Condensation on the walls of the firebox indicates that moisture is somehow seeping into your chimney. You may also notice rust on the firebox liner if it is made of metal, or on metal components like the flue or damper. In some cases, ashes left in the box may also become wet. Any moisture is cause for concern, so schedule an inspection before using the fireplace again.

2. Masonry Efflorescence

Efflorescence is the name of the white residue that forms on brickwork. Some efflorescence can be normal, especially if the masonry is less than a few years old. Efflorescence that suddenly shows up on older masonry can be a red flag that moisture is seeping into the brickwork somewhere. You may even be able to spot damage, such as cracked bricks, crumbling mortar, or a chimney pulling away from the house.

3. Mold and Mustiness

Mold growth or a severe musty odor from your chimney is another sign that moisture could be making its way inside. In this case, the leak may be high up the chimney, where you can't easily spot moisture seeping in from the firebox. Always consider a musty odor a warning sign of a leak and have it checked out by a professional so you can be sure your chimney is safe to use.

4. Wet Wall Boards

Leaks in the chimney brickwork can compromise more than the fireplace. In some cases, the moisture will also make its way into the walls or ceiling surrounding the fireplace. The wallboards may become soft, develop water spots, or the paint may begin to bubble and peel. Any water damage to the walls surrounding the chimney means there is likely damage that needs to be repaired promptly.

5. Indoor Smokiness

Your fireplace and flue is designed so that smoke and gasses should always be routed safely up and outside. If smoke is leaking back into your home or if your carbon monoxide detector keeps going off, you may have a chimney leak that is allowing these harmful substances to remain indoors.

Contact a fireplace maintenance service if you suspect that there may be a chimney leak.