How to Repair Chimney Leak

Mar 24, 2020Roofing0 comments

How to repair chimney leak

damaged chimney

Well, folks, we have survived another winter! Well, some parts of the country are still in winter mode, but for the most part, it is over, and summer is barreling down on us like a rodeo bull. So why are we talking about chimney repair?

Who uses their chimney during the spring or summer? Probably nobody, and that makes it a good time to do things like chimney repair and cleaning. Only after you have done chimney repair and inspection though should you worry about cleaning it.

There are benefits to be had by capping an unused chimney:

  • It keeps water from coming into the house every time it rains. Besides having a fireplace full of rain, the moisture that gets inside your house and attic isn’t good for the ceilings, floors, walls, and if anyone has breathing issues, that moisture makes it hard.  When the chimney gets too moist too often, the structure gets weak and then you need chimney repair service by a professional.
  • Without a cap on the chimney, you’ll experience downdrafts that will fill your house with smoke.
  • On a windy day, or in areas that are windy most of the time, a capped chimney cap helps with energy efficiency by keeping those cold blasts of air out.
  • Chimney caps with netting prevent animals and critters from getting in the chimney and into your house. Or worse, getting stuck in your chimney and dying, then you have an odor to deal with. Another time that you must call a professional chimney repair service to come to retrieve the dead animal and attempt to remove the odor.
  • The wire mesh that comes with chimney caps will keep sparks from flying out when you’re burning your fireplace.

Does a capped chimney need to be vented?

Yes, you need to vent your capped chimney so it can breathe, even if you aren’t planning to use the fireplace anymore. Moisture is a big problem with chimneys that aren’t maintained properly.  They get moisture trapped in them which causes them to deteriorate the structure of the chimney, then you need professional chimney repair service. That moisture also gets into the house, creating mildew, mold, and more problems. 

Seal your chimney either at the bottom or the top, but not both.  Air needs to pass through to keep that moisture to a minimum. Installation does well in sealing a chimney or a hydrophobic mineral wool insulation, a trading name is Roxul, used by almost all professional chimney repair contractors, which dries out should it get wet, as regular insulation will not.

How do you seal a chimney?

A chimney may be one of the most neglected parts of a home. Most homeowners won’t even think about maintenance and upkeep until they have a problem, then they are in a rush to find a chimney repair contractor. Like your roof, the chimney is exposed to the climate and elements 24/7. From rain to snow to sunshine, then back to ice. So, it is important to make sure it has a good sealant to keep it stable and strong. 

You can purchase the sealant materials and do the job yourself. Keep in mind, the chimney is higher than the roofline, so if heights are not your thing, sealing the chimney may not be.  This penetrating sealer is an excellent protector for chimneys from severe weather like rain, snow and hot sun rays. It also provides some protection from moisture. 

This siloxane-based sealer also creates a protective barrier around the chimney surface to prevent moisture without changing the chimney’s appearance. A bonus, it prevents mildew and mold from forming in the chimney too.

How do you repair a chimney mortar?

Mortar is the material that holds the bricks of your chimney together, and when it is fresh and new, it is smooth and solid. As time goes by, the mortar takes a beating and starts crumbling. A professional chimney repair contractor can fix this for you, or you can attempt to do the job yourself. Remember, the chimney is taller than the roof! 

We refer this chimney repair service as repointing and comprises scraping the crumbling mortar out then placing a new mortar in its place. These are the basic steps:

  1. With a joint raker, scrape out all the loose mortar.
  2. For difficult crumbling mortar, use a chisel and hammer and gently tap till it comes out.
  3. Using a wire brush, clear out any remaining bits and pieces of mortar.
  4. Spray the chimney with the garden hose, then wait 30 minutes.
  5. Mix a batch of mortar until you have a stiff peanut butter type of consistency.
  6. Using a pointing trowel, press the mortar you made into areas where you removed the old mortar, making effort to get to match the existing mortar.
  7. With the tuck-pointing tools, smooth the joints.


To fix chimney repair for a brick chimney, you want to determine what caused it to crumble and if it was moisture, fix that before you do anything else. Using the same steps that we described above for replacing mortar, do the same around the crumbling bricks.

After you have all the old mortar cleaned out and removed all the crumbling bricks, spread a layer of mortar where the bricks came out, then a layer on one side of a brick and put in place. Continue this process, staying in the same pattern as the existing bricks until done.

chimney in great condition


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