Why Is My Chimney Leaking?


If you discover a leak in your roof, it’s often a problem with the chimney stack. Chimneys can leak for lots of reasons, general wear and tear and age, being one, but chimneys can also leak if they have not been installed properly. Many older chimneys in particular will not have been built with the waterproofing that is needed to withstand rainfall.

Some chimney stacks are simple to waterproof and repair. Some are a little more challenging and call for specialised knowledge. Additional safety measures against leaks and water damage must be implemented when performing various chimney repairs. Some chimneys develop leaks quickly due to the manner the masonry was built. When these chimneys were first installed, there were no precautions to guard against porous brickwork damaging the house. It’s Bristow & Reeve’s job to put in place additional waterproofing precautions!

How To Waterproof A Chimney

Firstly, there’s some deconstruction to be done! Below the roof line, the chimney stack has to be entirely demolished. Then, two water trays constructed of lead (and that are completely watertight) are put in place. Weep-vents are then added to the brickwork so that water gathering in these water trays can exit through the chimney stack rather than saturating the brickwork. If the bricks become wet and are no longer able to hold water, rain might enter your home’s ceiling and attic. Because there is no water tray to collect the water, the wet bricks simply let in all the rain.

If you have any concerns or questions about using lead on your roof or chimney, see our article on how we use lead safely while roofing.

After the water trays are put in place, lead flashing is put in beneath each one to enable water to quickly drain off the roof and not to pool at the foot of the chimney.

In view of the recent bout of rather rainy and snowy weather, you must make sure that your chimney is watertight and that additional protections, such as a water tray, flashing, and weep-vents, are in place.

If you own a listed building, it’s particularly important to waterproof old masonry, so traditional brickwork doesn’t get damaged, but also to prevent your house from becoming damp through the chimney and causing more problems! For more ideas about how to renovate and maintain your listed building, see this article on How To Care For Listed Buildings.

Why not get in touch with us to learn more about the fixes we can make if your chimney leaks?