Leaks in your chimney can be the cause of major headaches and a costly business for the protection of your home. Often the chimney can be one of those parts of the home that we simply ignore, taking for granted its workability. And yet, sitting atop your roof and exposed to every kind of weather condition makes a typical masonry chimney prone, over the course of time, to deterioration.

And deterioration leads to problems; problems with leaks in particular. And when this occurs, you have reason to be concerned.

Water damaged chimneys can actually cause a hazard to the health and well-being of your house and all who dwell within. It can create damage to the lining of the chimney, blockages in the flue and issues around masonry which may have come loose or damaged – all of which pose genuine health risks.

Of course, a leaking chimney is akin to any other leak on your roof as well, and a potential cause of water damage or damp problems within your home; all of which is costly and detrimental to overall well-being. So, when looking at the overall maintenance of your roof it’s important not to neglect the chimney, recognising the key areas where leaks and water problems may arise.


Leaks in the Chimney Flashing

Flashing will traditionally be applied around the base area of the chimney where the stack meets the roof structure. It’s installed, as it is across other areas of the roof, to ensure you have a watertight seal on the brickwork. Often there will be gaps in the brickwork between roof and chimney and without the flashing in place then water may well be able to penetrate the roof / chimney and create a fairly serious leak problem.

Now, flashing materials such as lead flashing are very robust and long-lasting materials, offering excellent protection for a chimney stack. However, eventually, time will catch up with it and the flashing will begin to deteriorate which may expose gaps in the brickwork. Also, whilst flashing is a very tough wearing material, that doesn’t mean that it’s completely impervious to everything and impact from a foreign body, debris from a storm for example, may cause damage which needs to be addressed to stop damaging chimney leaks.

Looking for replacement lead flashing? Click here. If your looking for lead alternatives click here.

Leaks through the bricks and mortar


Bricks and mortar are not impervious to water. And, while that makes quite a nice little rhyme, it can be somewhat more serious issue for your chimney and a prime cause of leak problems. The reason for this is often that, whereas the structure itself is solid brick and generally fine, it’s not entirely uncommon to find that the inside of the stack may be comprised of an ad hoc variety of masonry, held together by the mortar. And while this won’t necessarily impact the structure of the stack, it might cause small cracks or tracks in the mortar which can lead to water penetration. Left over time this can seriously build up, saturating the brickwork leading to damp problems.

Over time, all brickwork and masonry will start to deteriorate due to the long-term effects of water and a chimney is no different. Which comes back to the notion that we all too often forget about our chimneys when thinking about the maintenance of our home. Once the masonry cracks and falters, water can seep into the bricks with damp and leakage next to follow.

Cracked Chimney Crowns


On the top of the brickwork lies the chimney crown – generally a cement covering out of which the flue will come. The reason for a chimney crown is to prevent rain, snow and other wintery elements from getting into the chimney and masonry.

Again though, over time this can become damaged, caused from shifts in the structure or shrinkage. The impact of hot and cold weather can cause the crown to expand and contract, causing movements over the years that can lead to small cracks in the surface. And small cracks will eventually become big ones which will let the water in and undermine the crown’s protective qualities.

This again comes back to the notion of incorporating your chimney into any periodic maintenance checks that you may carry out on your roof. By early detection of cracks in the chimney crown you can treat and repair it with an appropriate sealant which will provide added longevity. If, on the other hand the cracks go unnoticed then they will grow to the point that the only resolution is a complete rebuild of the entire crown.

Rain pouring into the chimney itself


Perhaps the most obvious of all chances of a leak in the chimney comes from water accessing the inside of the chimney directly from rainfall. If the top of your chimney is open to the elements then it stands to reason that you are likely to have water leaking in and potentially damaging the interior when it rains.

This is one of the reasons that it pays to ensure that you have a suitable chimney cover in place. Finishing your chimney off with an attractive chimney pot such as the Redbank Roll Top can add to the appearance of your chimney, but adding an appropriate cover to the top adds protection from water and indeed from other elements that can be problematic such as falling debris or even birds that can find their way into the chimney. Such incidences can not only lead to damaging leak problems but also blockages that can cause serious issues such as a dangerous CO2 build-up.


We may be aware of many of the inherent leak risks on a standard house roof, from ventilation to broken shingles and such like. However, it’s equally important to recognise when considering the maintenance and repair work on the roof that the chimney can represent an area in which leaks can become prevalent if left untreated or allowed to fall into disrepair. And a leaking chimney can lead to damage, unnecessary expense and even risks to health.


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