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Chimney Leakage: Common Causes And How To Fix It

Chimney leakage is unfortunate and will cause damage to your roof and inside the home if not repaired. Read below on the causes, what to look for, and how to fix it right away.

Chimney Leakage: Common Causes And How To Fix It - All Climate Roofing

Are you seeing water coming into your home through the chimney? Whether it’s condensation, rain water or another leakage, that water damage is going to cause you problems. If you want to correct it, you’ll need to locate the source of that leak.

Here are the most common causes of chimney leaks, and how you can fix them.

Chimney Leaks That Originate Elsewhere

Firstly, let’s cover chimney leaks that aren’t actually chimney leaks. If you are finding water rolling down the chimney, it’s always a good idea to check the attic. If there’s a bad enough leak in the roof, the water it lets in can make its way into your chimney. The stringer in your roof, the long piece of wood that spaces out the roof trusses, allows water to run down it and end up in your chimney. It’s a good idea to regularly inspect your roof from the inside out, so you can often stop this from happening.

If you’re getting a lot of condensation in your attic, that can also cause water to come down the chimney. It has to be a lot of condensation though, such as from a dryer that’s venting into the attic rather than outside.

Chimneys That Are Open to the Elements

One of the most common causes of chimney leaks is the fact that they’re open to the elements. Does your chimney have a cover on it? Then rain water just falls right into the chimney, leading to water issues. When you have a cover fitted, you’ll stop this from happening.

Also, be aware that a chimney’s greatest benefit is keeping out animals that may choose to nest in your chimney. When they do this, they cause blockages that are seriously dangerous for you. These blockages lead to CO poisoning, which is potentially fatal. Have a cover put on your chimney if you haven’t already, to ensure this isn’t happening.

Condensation Leaks 

Many people have spent thousands trying to fix a leaky chimney, but nothing works. If this is happening to you, that leak can actually be condensation. In these cases, the water isn’t actually coming from outside. The condensation happens because the gas fumes from your fire are low temperature and contain a lot of moisture. When this meets the cold brick of the chimney, it creates condensation.

This could be the cause of your water leak if you have an older home. There are many chimneys and fireplaces that used to be wood or coal burning, but now are set up for gas. If a proper chimney liner hasn’t been installed, then condensation will occur. Having one fitted now will help stop that condensation from happening again.

Cracked Chimney Crowns

The crown on your chimney is the cement top on it, which is designed to stop rain and snow coming in. When these are brand new, they can do the job admirably. After a while though, they will start to develop cracks. These usually come from the building shifting or shrinkage. Once those cracks appear, water can get right through them.

It’s important to address cracks as soon as they appear, even small ones. Over the winter, water will freeze in those gaps and make them larger, allowing even more water in. If you suspect that there are cracks, you’ll want to call on a roofing company to check it out. They will be able to patch any cracks to stop the leak.

Be aware that in some cases, the cracks will be too severe, and the crown will need to be reinstalled to fix the problem. You can avoid this happening again by using a chimney crown coating material. These are designed to prevent small cracks from appearing, allowing the crown to last longer without cracking.

Leaking Bricks

The cause of your leak could be the bricks of the chimney itself. Bricks and mortar are both porous, allowing water to pass through. If the bricks get wet in the summer, they will typically dry out again fairly quickly. The problem is that some bricks can’t dry out. If you live in a wet climate, or the bricks are on a side of the house that doesn’t typically get sunlight, then they’re going to stay wet. That water will need to find a way out, and so will fall down. If it gets inside your house, it’s going to start causing problems.

To stop this from happening, you can waterproof the bricks to ensure they can’t get wet in the first place. If you’re considering this, ensure you’re using the right waterproofing materials. Silicone waterproofing will trap water inside the bricks, and make things worse. A polysiloxane sealant will be best here.

Broken Flashing Around Your Chimney

Finally, a common reason that your chimney is leaking is because the flashing on it is damaged. Flashing is what protects the joints in your roof from water, such as the join between the chimney and the roof. It’s usually made from aluminum and is applied by inserting it between bricks and then laying it on top of the shingles. They’re then sealed into place. This has been done with tar in the past, but it’s not known for being long-lasting. Roofers are now using other materials that have a longer life.

The leaks happen because the sealant has worn away, or the flashing itself has seen damage. This most often happens after storms, where it’s had to withstand high winds or hail damage. To stop the leak, you’ll need to replace the flashing. This is something best left to professionals, as roofing jobs are dangerous. Plus, they have the know-how to install flashing that lasts for a long time.


These are some of the most common reasons for chimney leakage. Look for these issues in your home when you have a leak, as it’s very likely one of them will be the cause. Once you know, the solution is often simpler than you’d expect.