Repairing Chimney Crowns


If you are like most home owners, you’ve probably never paid much attention to your chimney crown. A chimney crown serves as a protective covering for the chimney against harsh weather. The crown serves an important role in protecting the chimney, but most people don’t realize that the crown also needs to be protected. When left unprotected, a chimney crown will eventually crack and deteriorate.


What is Freeze-Thaw Damage?

When you light a fire in your fireplace or wood stove in the winter, it causes the chimney to heat up and cool down. As temperatures drop below freezing, any water that is absorbed into your chimney crown from rainfall will freeze and thaw, creating a process of expansion and contraction. This process eventually causes your crown to crack and deteriorate. With this in mind, it is important to prevent water from absorbing into the chimney crown in the first place.

Depending on the severity of damage to your crown, it will either need to be totally replaced or repaired. Replacement costs often run in the thousands of dollars and should be performed by a qualified chimney sweep (visit for a qualified chimney sweep in your area). If the cracks aren’t too severe to warrant total replacement, the best way to to perform a chimney crown repair it is to use an elastomeric product that will remain flexible over time.


Use an Elastomeric Coating

ChimneyRx Brushable Crown Repair is a product that can be brushed on over the entire crown surface. It protects it from the elements as well as fills in the cracks, preventing further cracking and also waterproofing the crown. The benefit to using an elastomeric product like this one is that it remains flexible over time, preventing further cracks from occurring.

The first step is to take a wire brush to the entire surface of the crown. This will remove any loose particles, mold or debris that may interfere with the adhesion of the product. Next, take some duct tape and apply it around the perimeter of the flue tile about 1″ above the crown. Apply another line of duct tape around the perimeter of the crown base. This will give you a clean edge after you are finished.

If there are any cracks on the crown, use a high quality, exterior silicone or acrylic caulk to fill in any cracks. Allow this to set for 10 or 15 minutes. Don’t worry if it’s not totally cured before moving on to the next step as the caulk will cure beneath the surface.

Take a paint brush (a cheap throw-away brush like the one pictured on the left works well) and apply a thin, first coat of ChimneyRx Brushable Crown Repair to the entire surface of the crown. Allow it to set for about 5 minutes so that it becomes tacky. Next, apply a second heavier coat. If you’re making this chimney crown repair in hot weather, it may start setting up too fast and become difficult to smooth out. If this happens, you can mist the surface lightly with water using a spray bottle. This will make the product easier to spread and a little more workable.

After you’ve covered the crown with 2 coats and have smoothed everything out evenly, remove the duct tape. Clean up your tools with soap and water and your crown is now protected from further deterioration.

Further Reading

One important point to keep in mind is when dealing with chimney leaks and water penetration, there are 3 potential problem areas. The chimney crown is one potential source and it’s important to protect it. The 2 other sources of water penetration are the brick and mortar joints and the flashing. Read more about how to prevent chimney leaks and repairing chimney flashings to find out how to provide total protection for your chimney.


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