Why is My Brick Chimney Leaking? : A Maintenance Guide


Why is My Brick Chimney Leaking? : A Maintenance Guide

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Having a fireplace and brick chimney built into your home, lobby, restaurant, or lodge is a cozy luxury that humans have enjoyed for hundreds of years. A well-built fireplace is a marvel of medieval technology – keeping out the rain and cold weather while allowing smoke to rise and leave the building safely. However, when you start to see moisture coming down your brick chimney on the inside or water damage that appears near the chimney’s vertical line, you may have a chimney leak.

Why is your brick chimney leaking and ruining your cozy fireside plans? There are seven common causes and at least three different types of services that can help you solve them – depending on the source.


1. Crumbling Brick and Mortar

The single most common reason for an older brick chimney to leak is erosion. Eroding brick and crumbling mortar can leave the upper end of your chimney exposed to the weather, so that water begins to get inside your chimney through the gaps when it rains.

This is why it’s so important to keep an eye on your chimney and take care of routine brick care. Bricks that are maintained each year are less likely to take this severe level of wear-and-tear damage. Once your chimney is leaking from crumbled bricks and missing mortar, it is likely that the upper reaches of your chimney will need to be fully rebuilt to go back to cozy fires without the risk of cold drips.


2. Loose Chimney Flashing

Flashing is a thin metal strip sealed with a flexible sealant like tar or modern silicone that connects the brick to the roof. The flashing ensures that the connection where your chimney extends through the roof shingles does not cause leaks around the outside of the chimney column. However, over time the sealant that keeps flashing from leaking can wear away, which allows water to leak in through your roof around the chimney.

This can cause water to run down the outside of the chimney column brickwork, which is why you may be seeing water damage around the ceiling and walls near the chimney rather than seeing water trickling into the fireplace down the centre of the chimney.

To fix this, you will need your flashing reinstalled. We recommend installing new flashing to ensure top quality and a flawless seal so this problem does not repeat again.


3. Incomplete Gas Fireplace Upgrade

Another reason water might be leaking from your chimney into the fireplace is an incomplete gas fireplace upgrade. Classic brick fireplaces are designed to channel smoke out of the house, and this can be accomplished just with a flue and tightly built brick. However, the vapor from a gas flame actually includes moisture, which condensates on the interior sides of your chimney and then runs down the sides as water back into the fireplace.

If you recently installed a gas line into a classic brick fireplace and chimney system, you may experience what appears to be a chimney leak. Fortunately, the solution is simply to complete your gas fireplace upgrade – with a new chimney liner designed to handle condensate without drips.


4. Chimney is Missing a  Cap or Rain Cover

An open chimney top will, naturally, collect rain and create leaks into your fireplace. Fortunately, the solution was determined a century or two back: the chimney cap. This open-sided hat for your chimney keeps the rain off line an awning while allowing smoke to escape from under the cap. That is why the chimney cap is also called a rain cover.

If your chimney does not have a cap or rain cover – or your rain cover was blown away in a previous storm – then you may experience water getting into your chimney from above, which will seem like a chimney leak.


5. Cracked or Damaged Chimney Crown

The chimney crown is a slab of concrete that tops your chimney. Usually, one or two pipes come out of the cap, narrowing the total space where rain or small creatures can get in. If your cap or your crown are damaged, then you may experience rain leaking down through your chimney.

Over time, the concrete of your chimney crown can crack, which can allow a trickle of water or pieces might even break away for an even larger potential for chimney leaks from above.


6. Porous Brick Seeping

Bricks are naturally porous. In light rains, your brick chimney will absorb a little water, and then the bricks will dry out. However, in cool weather and long or heavy rains, the water cannot escape through evaporation, so it eventually falls down through porous bricks into the chimney itself or your walls near the brick chimney column.

If your chimney and local weather work together to create a chimney leak from water coming through the bricks, this issue can be tricky to fix, but the right professional chimney waterproofing can protect both your chimney and the other building materials nearby.


7. Leaks Deceptively Close to the Chimney

The final common cause of chimney leaks is that something is leaking near your chimney. Roof damage, cracks in your siding, or even a broken pipe inside the walls can sometimes appear near your chimney and appear to be a chimney leak. If a chimney inspection doesn’t reveal the issue, consider looking into the roof and nearby plumbing for sources of the water.


Whether you need a roofer, a mason, a plumber, and/or a water restoration service, it’s important to keep an eye on any chimney in your home or building and have it inspected at least once a year. For more great maintenance and care tips, contact us today.

Regional Services

Regional Services

Regional Services are an experienced commercial and office cleaning company based in London. Regional Services are an award winning and fully accredited cleaning company who provide a full range of facility management services and expertise including cleaning, maintenance, waste removal, pest control, gardening and more.


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