Cost Breakdown Of Waterproofing Your Chimney

A well-constructed chimney will last upwards of 100 years. When it comes to home maintenance, homeowners often overlook their chimney. With proper waterproofing, costly repairs resulting from water damage can be avoided.

A homeowner could spend anywhere from $60 to $300 on this project by waterproofing the chimney themselves. This method is cost-efficient since you pay for materials and not labor. When a professional is hired, the cost ranges a bit higher, varying from $150 to $700.

Not all waterproofing projects are as simple as applying a waterproofing coating. There are a handful of things to consider when it comes to making sure your chimney is water-resistant. What does it mean if there is a leak in the ceiling near the chimney? Do you need a chimney cap, and why is that an important part of waterproofing? How long does a waterproofing service last? These questions and more are answered below, so let’s dive in.

How Much Does It Cost To Waterproof Your Chimney

The most common materials used to waterproof your chimney with have a cost ranging from $60 to $150. If you waterproof your chimney yourself, the materials make up all the costs. If you have your chimney waterproofed professionally, you’ll need to pay an additional $90 to $400 extra for labor.

Waterproofing a chimney is definitely something you can do yourself, but you need to have some knowledge of it. Generally, it’s recommended to have it done by professionals, because if it’s done incorrectly, you can get some serious water damage.

Hiring a professional to waterproof your chimney costs more since you are also paying for labor on top of materials. Professional services vary in range, but usually remain below $1000. Here are some methods of waterproofing your chimney.

The added costs of having it done professionally well outweigh the costs of fixing structural damage and water damage.

The same goes for materials used. Cheaper materials may appeal to your wallet, but will it stand the test of time (and weather)?

Masonry Sealing

The most basic waterproofing is to have the masonry on your chimney sealed. As mentioned above, the materials can be purchased for as low as $60 and applied with a sprayer and brush. For porous masonry (meaning the material absorbs moisture), a liquid-based formula—like a siloxane—works well to block water from entering the masonry.

A siloxane product also allows water vapor to escape. You want the water vapor to escape so that in freezing temperatures, trapped water will not expand and cause cracking.

Different products may be recommended for other types of non-porous masonry, such as stucco or paints rated for use on a chimney.

Chimney Cap

According to HomeAdvisor, replacing or adding a cap on average costs $300.

A chimney cap is essential to keep water out of your chimney. It also keeps the pests out. A chimney cap should always be installed and if your chimney is missing one, call a professional to measure and install one for you. 

Although a chimney cap does not seal the top of your chimney so that no water enters, it does help lessen the amount of rain and snow from entering through the top of your chimney.

Chimney Crown

The average cost of repairing a crown usually is less than $500. 

Chimney crowns are another method of reducing water from entering through the top of your chimney. The crown is the cement at the top of your chimney where the cap meets the brick and mortar.

Chimney Flashing

HomeAdvisor suggests that the average cost of repairing or adding flashing ranges from $200-$500.

Chimney flashing is important because it closes the gap where your chimney meets the roof. If left without flashing, water can seep down into your home. This can lead to leaks in the ceiling near the chimney.

Is Waterproofing A Chimney Necessary?

Waterproofing your chimney is necessary because it ensures that your chimney is protected against damage from water, snow, and ice. As chimneys are made of a porous material, it absorbs moisture over time. This could lead to a myriad of issues.

For instance, an improperly cared for chimney can lead to:

  • Structural damage: When water leaks into the masonry, it deteriorates faster. Likewise, when there is no flashing, water seeps through the roof and can cause damage to the attic or ceiling. Without a chimney cap, water can pool inside the chimney and damage the flue lining.
  • Mold: Water damage to a ceiling or attic can lead to mold issues.
  • Reduced lifespan on the chimney’s masonry: Water that is absorbed into the masonry eats away at the cement or mortar and can also expand inside the brick during freezing temperatures.
  • Pest issues: Without a proper cap or chimney crown, pests can get inside the chimney and cause issues such as birds making a nest or squirrels storing nuts inside.

How Often Do I Need To Waterproof My Chimney?

Proper waterproofing will last upwards of 20 years. Given that the waterproofing product sprayed onto your masonry will wear down over time, it is a good rule of thumb to waterproof the masonry every 10-15 years.

Make sure that your chimney crown and chimney cap are in good condition when you have your routine cleaning done. If your fireplace is used regularly, then it is recommended to have your chimney cleaned annually.

Ask the professional cleaner also to perform an inspection of your chimney. This way, they can alert you if the crown or cap is in bad repair.  

How Is Waterproofing Applied On A Chimney?

The waterproofing material is sprayed directly onto masonry that is porous (brick or cement block). You may also need a brush to apply in hard-to-reach areas. Typically, two coats are recommended, with extra attention given to the top of the chimney where it is most exposed to the elements.

If your chimney is made of a component other than a porous material, then a stucco or paint can be applied to help waterproof the chimney. A certified professional can help you to pick the correct product to use on your chimney.

If you apply the product yourself, make sure the product is non-flammable (since it will be going onto a chimney, you certainly would not want it to be combustible) and that it is of quality and will give you the protection you need.

Dan Westfield

Hi everyone! My name is Dan and I currently have two fireplaces, a wood-burning and a gas one. I cannot live without them and love to share my passion with you all!

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