Chimney Leaks – Finding and repairing chimney leaks – video

How to look for leaks on a chimney

This video explains why the chimney is leaking

Watch this video to see how we wrap it with a membrane to preserve it.

A Chimney consist of three sections:

  • Crown
  • Body
  • Flashing

If you need a checklist of what you will need to repair your chimney you can find it here.

Chimney leaks - Chimney Sections Labeled
Illustration of Chimney Components

The following is a list of materials used on chimneys:

  • Bricks
  • Fieldstone
  • Cement block
  • Wood frame with Siding
  • Metal Stove Pipes
  • Stucco
  • Metal or Copper Flashing


The Crown of a chimney consists of a slab of cement that poured on site. Its purpose is to seal the top, but over time, small cracks develop and water seeps into them.

Body and Crown

Image Description: This cement slab has developed a crack causing a separation of the CROWN and BODY.

Water is free to enter into the chimney. In freezing temperatures, rain expands causing the cracks to become larger. A maintenance inspection is crucial at this stage. Sealing the small cracks can prevent larger cracks during the ongoing freeze and thaw cycles.

Chimney Leaks - When the cement slab separates from the bricks, water then can get inside the chimney busting the bricks during freezing.

Chimney Flashing

Flashing connects brick and mortar to the roofing system. Over time, the seal between the mortar and flashing will deteriorate causing water to seep in.

Skylights have similar flashing then that of chimneys and could also cause leaks. Check this out for skylight leaks. 

A cut-away view of a chimney crown shows what it looks like. When water gets through the cement slab, the bricks absorb the moist and finally will crack during winter.

When a chimney is very far gone and the grout is loose or missing. When a chimney is not an aesthetic part of the building, then it could be better to wrap the entire chimney with a membrane.

This will keep the chimney intact and it’s a very inexpensive solution to the problem.

The cement slab shown in image is what a cement slab should look like. This is not the case with most chimneys.

Watch the video below: How to Inspect your Chimney.

Wrapping a Chimney with Torch Down membrane

It is often the case that a chimney is not part of the aesthetics of a building. In many cases, contractors, handyman and other people have tried to seal the chimney with tar to stop it from leaking. This kind of fix is common and a solution that is very temporary. The reason why covering it with tar does not last is, that the tar will dry and start cracking causing water to be trapped behind the tar. This could lead to ice build up during the winter and cause the brick or cement to crack.

The other problem is, that the transition from the roof to the brick chimney is compromised. Just smearing tar to make a seal will not last. Many times when we clean the old tar off, we will find existing copper flashing underneath all the tar build up. By smearing tar over the chimney made the problem worse.

With tar all over the chimney, we deduced that aesthetics is not that important. In the video, you will see the process of covering the chimney with a membrane. The chimney looks better, and since the rubber membrane will not dry out or crack, water will never leak into it again. This is the most cost-effective way to preserve a chimney without having to tear it down and build it back.

Image of a Chimney in New York

The tar covered chimney is flaking off and cause cracks in the stucco. Instead of tearing down and rebuilding it, we removed the asphalt as much as possible and wrapped it with a torch down membrane.


Close up view reveals cracks

This is a close-up view of the surface of the chimney. Notice the cracks in the stucco. These cracks happened over time when the tar cracked and trapped water behind it. With thawing and freezing, the ice would work its way into the cement and open the cracks further. This type of problem can destroy a chimney rapidly to where it has to be replaced.

Cracks-on-chimney in NY

After loose tar has been removed.

This is just another angle to show the preparation to get it ready for the membrane. Notice the copper flashing at the bottom of the chimney. Although there was copper flashing, the cracks on the side of the chimney caused the water to seep in.

Chimney in New York prepped fro wrapping
Chimney in Brooklyn NY that needed to be sealed

Using a Torch to burn the old tar off

Part of preparing the surface of the chimney is to remove as much as possible of the old tar and debris build up. It makes the membrane stick closer to the surface and it just looks better when the rubber membrane is flat and smooth against the chimney.

Chimney-in-NY prepped for wrapping
Using a propane torch to burn most of the old tar off the chimney

After wrapping the Chimney with Modified Bitumen Torch Down Rubber

This is what it looks like after we completed wrapping the chimney. The rubber will never crack or peel and this chimney was preserved at the fraction of the cost what it would have cost to rebuild it.

Chimney-in-New-York after wrapping it
This is what the chimney looks like after wrapping it with a rubber membrane

This Chimney was completely wrapped

This is an image of another chimney that was completely covered with the rubber membrane.  This photo was taken 10 years after this wrapping was done. It is clear that the membrane is a solution to most chimneys with cracks and tar.

Chimney wrapped entirely with Modified Bitumen torch Down
Entire chimney wrapped in roofing membrane to prevent leaks

Fieldstone Chimneys are pretty butt…

Fieldstone chimneys are common in Connecticut. They are there to enhance the aesthetics of the building. Our experience id that they cause the most problems when it comes to leaks on a roof. The fieldstones that the chimney is built from, have cracks in themselves. Then the cement or mortar does not bond to the stone properly.

A fieldstone chimney that is leaking
Chimney Crown has cracks causing leaks

Cracks in Chimneys built from Fieldstone

No matter how well the chimney is built, there will always be cracks in a fieldstone chimney. Notice how the cement has separated from the stone and how big the cracks are.

Fieldstone chimneys always have cracks in them
Notice the cracks among the stone and cement joints

The most common problems with chimneys is the Crown

The crown is the cement slab on top of the chimney that covers the bricks. The cracks are due to the thin slab of cement that was poured. Most masons will slope the slab down to the edge for water to run off, but this, in turn, will become a bigger issue for that chimney.

Crown of the chimney cracked
The thin cement slab that is the crown, is separated from the bricks. This is common with most chimneys. The easiest fix is with Super Silicone Seal or Turbo Poly Seal

Flashing on Chimneys

Another common problem with chimneys is the flashing. To make the transition from the metal flashing onto the surface is not always that easy. First of all, a groove has to be cut into the surface, then the metal flashing has to be bent to be inserted into that groove. This transition often causes a leak. That’s why you will often find someone has caulked that groove to make a seal between the metal and the chimney surface.

Copper flashing on chimneys
Notice the transition from the copper flashing to the bricks only have a small beat of caulking. The caulking will not last and water will leak in behind the flashing

This is a video showing how we removed cement grout from a fieldstone chimney

Removing the grout form a fieldstone chimney and preparing it for re-pointing

In the images below notice all the chimneys smeared with tar

Tar is used in most cases to seal chimneys. This is not a permanent solution. The tar will eventually dry and crack causing more problems. We wrap our chimneys with a membrane and that way we ensure a maintenance free chimney. Watch the next video that explains it very well.

Most common way to prevent chimneys form leaking is to cover it with tar. Using Turbo Poly Seal or Super Silicone Seal will last much longer

Watch this video to see where to look for a possible leak on a chimney

Below is a video showing what appeared that the chimney was leaking but instead the wall butting up to the chimney
The wall connecting to the chimney is causing the leaks
This video explains how to use a rubber membrane instead of tar to cover it
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