This job can be dangerous. Consult or hire a pro to be safe.
Time to complete
4 hours
Cost
$100–$500
This DIY requires supplies and safety equipment
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What you'll need:
TOOLS
Ladder
Safety harness
Work gloves
Drill
Measuring tape
Caulk gun
Wire brush
Goggles
Dust mask
Hose
Scraper
Marker
Bucket
Water
SUPPLIES
Chimney cap
Masonry drill bit
Masonry screws
High-heat silicone sealant
Brick-and-mortar cleaner
Although it may seem like a minor exterior detail, a chimney cap has an important purpose. It is a mighty shield that prevents rain, snow, leaves, and critters from entering your chimney while improving ventilation. Knowing how to install a chimney cap is the first step to ensuring your chimney stays safe and functional for years, whether you decide to install it yourself or hire a pro.
The first step is to measure for a chimney cap. If your chimney has a square or rectangular flue, measure the outside length and width. For round flues, you'll need to measure the inside and outside diameters to ensure the cap fits properly. Remember, selecting the right size cap is essential for proper airflow and protection—these measurements should be as accurate as possible.
Safety is everything when working on a roof. Wear shoes with a good grip and use a ladder with a stabilizer. If your roof has a steep slope, especially over 35 degrees, hire a professional to handle the installation. If this is not possible, you should wear a safety harness attached to a weight-bearing anchor point to prevent a dangerous fall.
Purchase Your Chimney Cap
Chimney caps are either single-flue caps, which fit individual flues, or multi-flue caps, designed to cover multiple flues at once.
When choosing the right cap, consider the material. Stainless steel is durable and rust-resistant and works well in most climates, while copper adds decorative appeal but requires more maintenance.
Additionally, you may consider a cap with a mesh screen to keep out animals and debris. If you live in an area with heavy rain or snow, a cap with a solid top is ideal for preventing moisture from entering your chimney.
Clean Your Chimney Crown
Photo: gabort / Adobe Stock
It is essential to clean then chimney crown thoroughly before installing a chimney cap. Use a wire brush to remove loose debris, leaves, and soot. A scraper is helpful for tough spots. For extra sooty conditions, you can scrub using a brick-and-mortar cleaner. Just dilute some of the cleaner in a bucket filled with water.
Afterward, grab your garden hose to rinse off the crown, then allow it to dry completely. This necessary step prevents moisture from being trapped under the cap.
While cleaning, look for cracks or damage that need to be repaired before proceeding. Having your chimney swept and inspected by a pro is also a good idea to ensure you do not miss structural damage.
Test the fit of your chimney cap before installation, following the manufacturer's instructions. The steps may include checking for stability and clearance between the top of the cap and the flue opening, so smoke and gases can exit while preventing downdrafts. Once you ensure a good fit, hold the chimney cap and mark your pilot drill holes.
Install the Chimney Cap
Use your drill and a masonry bit to create pilot holes in the chimney crown. These holes will guide the screws and ensure a secure fit for the cap. Once the pilot holes are ready, fasten the chimney cap in place using masonry screws or mounting brackets, depending on the manufacturer’s instructions.
Remember to drive the screws or brackets firmly into the masonry. Securing the cap tightly is essential to prevent it from shifting or coming loose during high winds and other weather conditions, which can test its durability over time.
Apply the Sealant
Grap your caulk gun and carefully apply a generous bead of chimney-appropriate sealant around the entire base of the chimney cap, focusing on the areas where it meets the chimney structure. This will create a watertight barrier that helps prevent moisture from seeping into any small gaps and blocking drafts that could compromise your chimney's efficiency.
Be sure to apply the sealant evenly to ensure maximum coverage and protection. Most sealants need adequate time to cure before they become fully water-resistant. This process typically takes 8 hours in low-humidity conditions but may take longer in more humid environments.
Test Your New Chimney Cap
To test your chimney cap, inspect it for secure installation, ensuring there are no visible gaps or loose parts. Next, check for proper airflow by lighting a small fire in the fireplace and observing the smoke. It should rise and exit through the chimney, indicating that the cap allows ventilation.
When rain is forecast, observe how the cap performs in keeping moisture out and inspect afterward for any water seepage inside the chimney. Remember, annual chimney inspections will help ensure the cap is functioning effectively.
Cost to Install a Chimney Cap
The average cost to install a chimney cap is $300, but you can expect to pay between $75 and $500. Material plays a big part in the cost, with galvanzied steel being the least expensive at $15 to $200 and copper costing up to $900, depending on shape and size. As with most products, the larger the cap, the higher the price tag, and an oddly-shaped chimney may require a costly custom cap.
DIY vs. Hiring a Pro
While installing a chimney cap as a DIY project can be cost-effective, you must have relevant experience, be comfortable with heights, and own the necessary safety equipment. It's also wise to have a buddy spot you while working. We don’t recommend attempting this project yourself as any kind of roof work can be dangerous.
A local chimney cap installer will ensure great results that meet local guidelines. Remember, pros have the proper equipment, experience, and knowledge to install the cap securely, and they can spot any issues with your chimney that might require attention.
Frequently Asked Questions
Chimney caps last 10 to 20 years, depending on the material and local weather conditions. Stainless steel caps are highly durable and resistant to rust, often lasting 20 years or more. Copper caps also have a long life span but may require more maintenance to retain their appearance. Galvanized steel caps are less durable, often lasting around 5 to 10 years before rusting or corroding. Regular inspections and maintenance can help extend the life of your chimney cap.
Yes, a chimney cap is an excellent idea for several reasons. It prevents debris, rain, or snow from entering your chimney, which can cause moisture damage or blockages. A cap with a mesh screen also keeps animals like birds, squirrels, and bats from nesting in your chimney—or worse, getting into your abode. Additionally, chimney caps help prevent downdrafts, which can push smoke and harmful gases back into your home. Lastly, by installing a chimney cap, you will improve safety and enhance the overall efficiency of your fireplace.
Chimney caps offer many benefits, but there are a few potential downsides. A poorly fitted cap can restrict airflow, leading to poor chimney performance or draft issues. Caps with mesh screens can occasionally become clogged, requiring regular cleaning to maintain proper ventilation. Additionally, cheaper or low-quality materials, such as galvanized steel, may rust or corrode quickly, leading to frequent replacements. Despite these cons, choosing a well-made cap and correctly installing it outweighs any drawbacks, improving chimney safety and efficiency in the long run.
Yes, gas fireplaces benefit from chimney caps just like wood-burning fireplaces. While gas fireplaces produce fewer byproducts, a chimney cap still helps prevent rain, debris, and pesky critters from entering the chimney, which can cause blockages or damage. It also prevents downdrafts that could push harmful gases like carbon monoxide back into your home. Even with the cleaner operation of gas fireplaces, a chimney cap adds a layer of protection and helps maintain proper ventilation.
Deirdre is a seasoned DIYer and home improvement writer. She believes in the transformative powers of deep cleaning and painting to revitalize any space. Her articles have appeared in HomeLight, The Spruce, Realtor, and more.
Deirdre is a seasoned DIYer and home improvement writer. She believes in the transformative powers of deep cleaning and painting to revitalize any space. Her articles have appeared in HomeLight, The Spruce, Realtor, and more.
The homeowners guide to Chimney Caps
From average costs to expert advice, get all the answers you need to get your job done.
