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How To Install a Chimney Cap

Preparing to install a new chimney cap? Read our guide to learn about the different types and how to securely install yours.

Default Author Icon Written by Angela Bunt Updated 05/20/2024

A chimney cap is a steel or mesh covering that protects your chimney from external elements. Without a chimney cap, birds, snakes, or small animals such as raccoons can enter your chimney and build a home. Moisture, as well as debris like twigs and leaves, can also pose serious issues, leading to flue damage and the potential for chimney fires. If your home has an operating chimney, then you need a chimney cap. 

Chimney cap installation is a project you can complete yourself if you’re comfortable working from a ladder and getting on your roof. You can install a new chimney cap or replace an existing one by following a few simple steps. Read our guide to learn about the different types of chimney caps, the steps for installation, and when to hire a professional.

Types of Chimney Caps

Chimneys come in different shapes and sizes. Some have extended flues or multiple flues, and some have a flue that is flush with the chimney’s crown. Finding the right fit and a cap that meets your needs is essential. Regardless of the type, chimney caps tend to be made from copper, stainless steel, or galvanized steel. Here are some common chimney cap types to choose from: 

  • Full-coverage cap: These caps provide complete coverage over the top of your chimney. They’re easy to customize and are designed to match your home’s aesthetics.
  • Multi-flue cap: These caps are similar to single-flue caps (see below) but are big enough to cover more than one flue. You should top-mount multi-flue caps regardless of whether the flues are extended. 
  • Outside mount cap: These caps are designed to extend beyond the edges of the chimney to provide additional protection against moisture. You should install them directly on top of the chimney crown. They are available in single- and multi-flue options. 
  • Round chimney caps: Venting wood-burning stoves sometimes air out into round metal chimneys. Chimney caps for these chimneys either fasten to the flue exterior or slip into the flue. 
  • Single-flue cap: These caps are designed to cover a single flue and come in a variety of shapes to match different flues. Single-flue caps are designed so that you can either attach them to an extended flue or use legs or brackets to attach them to a chimney with a single flue that is flush with the crown.  
  • Specialty cap: Various specialty caps are designed for unique situations in which the chimney cap needs to help the chimney perform a specific job. For example, draft-increasing chimney caps and wind-resistant caps can help prevent downdrafts. Spark arrestor caps are ideal in areas prone to wildfires, and some other specialty caps are designed with decorative features to match your home.

Tools and Materials Needed

Before you purchase and install a chimney cap, you’ll need to obtain the necessary tools and supplies and measure your chimney. Be sure to pick up these supplies:

  • Brush: Used to clean the chimney crown
  • Caulk gun: Used to apply adhesive
  • Chimney cap: Your new chimney cap
  • Construction adhesive: Used to secure the chimney cap in place
  • Extension ladder with stabilizer: Used to safely climb to the roof and access the chimney
  • Marking pen, marker, or pencil: Used to mark bolt and screw placement as needed
  • Masonry screws: Used to attach the cap to your chimney flue or crown (metal screws may be required for round metal chimneys)
  • Measuring tape: Used to take accurate chimney measurements
  • Power drill: Used to secure screws in a metal flue
  • Safety harness: Used for safety when working on the roof

Steps to follow

You’ll need to follow the proper installation process to ensure your chimney cap fits and performs its best. You’ll need to measure your chimney for an accurate fit and take precautions to ensure your chimney cap is properly secured. 

Measure the Flue Opening

Getting the right fit is crucial to your chimney cap’s performance. Get your measuring tape, pad of paper, pencil, and safety harness before setting up your extension ladder and climbing onto the roof. Use your measuring tape to get specific measurements depending on your chimney type: 

  • Flush flue: Measure the length and width of your chimney crown.
  • Multi-flue: Measure the length and width of both flues, the height of the tallest flue, and the length and width of your crown.
  • Round flue: Measure the outside and inside diameter of the flue. You’ll use the outside measurement for a cap that bolts to the outside and the inside measurement for a cap that slides inside the flue.
  • Single-flue chimney: Measure the outside length and width of the flue and the height of the flue emerging from the chimney. 

Purchase Your Chimney Cap and Supplies

Armed with your measurements, visit your local hardware or home improvement store to find a cap that will fit your chimney and match your needs. Single-flue chimneys need a cap that matches the length and width of the flue. Multi-flue chimneys need a cap that fits both flues without going over the crown. 

Seek the following qualities for a good match.

  • Choose a cap that’s at least 6 inches taller than the flue’s height.
  • Look for a cap with side mesh that’s about three-fourths of an inch per opening.
  • The cap should be within one-half to 1 inch of your flue’s length and width or diameter.

Clean Your Chimney Crown

Before installing your new chimney cap, get rid of any debris that could get trapped between the crown and the new cap. Secure your ladder in place, and climb onto the roof. Remove the old chimney cap if there is one, and use a stiff-bristled brush or chimney brush to clean the crown.

Place the Chimney Cap

The manufacturer’s instructions will help you place your cap correctly. Some caps have support systems that screw into place. Others slide into the flue and have metal fasteners or no attachments at all. 

For an extended flue chimney, slide the cap over the flue and press down on it until it’s fully seated. If you have a flush flue chimney or are using an outside mount cap, you’ll need to center the cap on the crown and mark the locations of the screw holes and the outside perimeter of the cap. Use the markings to drill pilot holes with a drill and masonry bit.

You should not use caps with minimal or no fasteners in areas with high winds. Clay flues can be brittle, and screws can damage them. If you’re inexperienced, you may need to consult a professional for guidance. 

Secure Your Chimney Cap

You’ll most likely need to secure your chimney cap with appropriate bolts for the materials and adhesive for a firm fit. Check the manufacturer’s instructions to determine whether you need to apply adhesive before placing the cap or after the screws are in place. 

  • Clay flue: Anchor the cap by placing masonry screws into drilled pilot holes that match the cap.
  • Flush flue: You’ll need to screw the cap into place by inserting masonry screws into the pilot holes you drilled during the fitting process.
  • Metal flue: Use a power drill to secure the cap with its designated screws.
  • Round flue: Some round flues come with clamps instead of screws. These clamps wrap around the cap’s base, after which you’ll need to tighten them with a screwdriver. 

When To Hire a Professional

Chimney cap replacement is a job that requires you to work on the roof and make changes to your chimney. While it’s a feasible do-it-yourself (DIY) job for some homeowners with experience, it’s not a job everyone will feel comfortable completing. 

If you’re not comfortable with heights or working on your roof, hiring a professional is the best option. Even if you plan to complete the job yourself, there are times when a pro is better equipped for it. If you think you could damage your flue or you don’t understand how to secure it properly, then consult a professional. 

When hiring a professional, look for a licensed chimney cap installer with several years of experience in the industry. Ask questions to learn what’s included in the service, and seek out reviews from satisfied customers before choosing the right company for your professional chimney cap installation. 

Maintenance Tips

Since chimney caps are typically made from stainless steel and copper, they require little maintenance. However, you should examine your cap on a regular basis for damage or obstructions. 

  • Check your chimney cap twice annually for holes in the mesh, debris that could obstruct airflow and creosote buildup. 
  • Hire a local chimney sweep to help maintain your chimney and chimney cap.
  • Repair any damage and replace any damaged mesh before starting a fire in the cool season.

Our Conclusion

A chimney cap helps keep debris, moisture, and critters from entering your chimney. If you’re planning a DIY chimney cap installation, make sure you understand what tools you’ll need and how to ensure a proper fit and a secure installation. 

But if you’re uncomfortable dealing with heights, working on the roof, or unsure about the mechanics of installing a chimney cap, hiring a professional is the best option. In many cases, you may be able to bundle chimney cleaning and cap-changing services to get a better deal.

FAQ About Chimney Cap Installation

Is a chimney cap necessary?

Chimney caps are necessary for homes with operating chimneys. They prevent sparks from leaving the chimney and objects from entering it. They also keep out moisture, debris, and wild animals.

Can I install a chimney cap myself?

You can install a chimney cap yourself if you’re comfortable working from ladders and climbing on your roof. If you’re afraid of heights or unsure about your ability to install a chimney cap, you should contact a professional.

Do chimney caps keep rain and snow out?

Chimney caps keep out rain, snow, ice, and moisture from dew and humidity. This helps avoid corrosion and flue cracks.

How long does a chimney cap last?

Stainless steel and copper chimney caps can last over 50 years. However, severe weather, wild animals, and standard wear can all damage your chimney cap. You should inspect your chimney cap during your annual chimney inspection and replace it if it becomes rusty, broken, or sustains other damage.

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