The Complete Guide to Chimney Cap Installation

There’s nothing better than sitting by a warm fireplace, surrounded by your family and friends. But even though they may seem useless, you’ll want to make sure you have a functioning chimney cap to keep your home safe. 

Chimney caps perform an important function – these protective coverings prevent water and pests from getting into your home through the fireplace. The fireplace’s flue, or the tube which acts as a vent, can quickly become filled with water, damaging your fireplace and roof. Plus, nests from birds or rodents inside the flue can become a fire hazard, putting you and your family at risk! Avoid all of these potential issues by installing a chimney cap. 

If you’re comfortable doing so, you can always install a chimney cap yourself. However, we highly recommend calling a professional if you aren’t comfortable climbing a ladder and working on a roof, if your home has a steep or slippery roof, or if you lack the proper safety equipment needed. Either way, here’s everything you need to know about chimney cap installation. 

Benefits of Chimney Caps

While it may seem pointless, a chimney cap is actually pretty important to your home. In fact, chimney caps help keep your home safe and functional by:

  • Reducing Moisture. Water will inevitably get into your chimney at some point, especially if you live in an area where it rains excessively. However, you’ll want to keep out as much of this moisture as possible for several reasons. First, moisture in your chimney can create a breeding ground for mold and mildew. You might not even know it’s there at first, but eventually, it can make you or your family sick and create an unpleasant smell throughout your home. Plus, water in your chimney might damage the dampers, liners, or mortar joints – all of which are costly to repair or replace. Finally, a moist chimney can increase humidity levels in your home, making your space less comfortable over time. 
  • Keeping Out Unwanted Pests. When it’s warm outside and you aren’t using your chimney as much, birds, rodents, and other animals might get the wrong idea about the space. If they can easily get inside, they’ll use your chimney as a nest. More often than not, nesting material is highly flammable and can cause a fire the next time you light your fireplace. Plus, unwanted pests can crawl through the chimney and enter your home. You don’t want to deal with that! A chimney cap can prevent animals from getting into your chimney in the first place. 
  • Blocking Drafts. A chimney is like a perfect tunnel for airflow. If left uncovered, a draft can flow through it and enter your home, lowering the temperature significantly. Plus, if you have a fire going, a draft at the perfect angle can blow your fireplace and potentially lead to a house fire if you aren’t careful. 
  • Eliminating Sparks. Just like a bonfire outside, your lit fireplace will produce embers and sparks. Sometimes, these embers will travel up through your chimney and make their way outside. It only takes one spark to start a fire – either on your roof or on the surrounding foliage. Don’t take this risk. Your chimney cap should have a spark arrestor which will stop any embers from making it outside and starting a fire. 
  • Preventing Blocked Flues. Just like your gutters, your chimney can become clogged with foliage, dirt, and other debris in a matter of minutes. When you light your fireplace, a house fire can easily start if your chimney is filled with debris. Even if a fire doesn’t start, the clog can block smoke and carbon monoxide from exiting your home, causing it to travel right back inside of your home. You won’t want to deal with these unpleasant and dangerous fumes. 

So, as you can see, chimney caps are for more than just aesthetic appeal. They perform several important, and sometimes life-saving, tasks. Don’t wait to deal with the consequences of not having a chimney cap installed.

What Type of Chimney Cap Do I Need?

Before you begin to think about installation, you’ll first need to decide on what type of chimney cap you need. There are many different options, sizes, and materials to choose from. Keep reading to learn the differences.

Different Types of Flues

Some chimneys have multiple flue openings, while others just have one. You’ll want to purchase a chimney cap that fits however many flues your chimney has. Furthermore, your chimney flue might be square, round, or oval-shaped. This will also impact what kind of cap you’ll need to purchase. Finally, your flue or flues might be directly mounted to the crown of your chimney, or they could be flushed to the side. If it is flush, you’ll want to use a top-mount chimney cap to cover the entire crown. 


The most common materials for chimney caps are galvanized steel, aluminum, stainless steel, and copper. They vary in efficiency and cost. 

Galvanized steel will be the cheapest option, but they are the most flimsy and most likely to corrode. Aluminum is another more affordable option. While these chimney caps are less likely to corrode, they still aren’t very durable. Both of these options are effective if you have a tight budget, but they won’t last as long as some other caps would. 

If you’re able to spend more money and get a more durable chimney cap, then you should look into stainless steel or copper. Stainless steel is where you’ll get the best bang for your buck. Although they are pricier than galvanized steel or aluminum, stainless steel caps will last much longer and are resistant to corrosion. On the other hand, copper caps are the sturdiest option on the market. However, you’ll pay nearly four times more than you would for a galvanized steel cap. But, a copper cap will last the longest and look the best on your roof. 


Before you purchase a chimney cap, you’ll need to determine a size. There are different ways to measure, depending on the shape and number of flues. 

For a square flue, measure the length and width of the outside of your chimney. For a round flue, you’ll measure the diameter of the inside and outside of your chimney. If there are multiple flues, you’ll want to measure the height of the tallest flue along with the width needed to cover all flues at once. 

How to Install a Chimney Flue – DIY Guide

If you feel capable and comfortable installing your chimney flue, be sure to follow all safety guidelines to avoid any unnecessary risk. 

  • Don’t use an A-frame ladder. Instead, use an extension ladder with a ladder stabilizer. Extend the top rungs of the ladder at least three feet above the gutters.
  • Never work on your roof alone. You should always have a partner who is available to hold the ladder for you and pass equipment to you. Climbing a ladder and working on your roof can be incredibly dangerous. Always use caution!
  • Consider wearing a safety harness or helmet for extra protection. It’s better to be safe than sorry!

After you’ve reviewed the safety guidelines and purchased the appropriate chimney cap, follow the steps below to DIY and install your new chimney cap:

Single-Flue Chimney Cap Installation

  1. Position your extension ladder on stable ground and have your partner hold it in place. Climb the ladder and mount the roof. Have your partner pass the following tools to you: your chimney cap along with provided screws/clamps, a screwdriver, and high-temperature sealant or other construction adhesives.
  2. Lower your chimney cap onto the flue, positioning it at least 6 inches from the top of the flue to allow room for fume exhaustion.
  3. Screw the provided self-tapping screws through the holes along the cap’s rim and into the flue. Tighten the screws until your cap is held firmly in place.
  4. Some caps have a clamp that you’ll need to attach as well. 
  5. Apply a high-temperature sealant or other construction adhesives to fully secure your new chimney cap. 

Multi-flue Chimney Cap Installation

  1. Position your extension ladder on stable ground and have your partner hold it in place. Climb the ladder and mount the roof. Have your partner pass the following tools to you: your chimney cap along with provided screws/clamps, a power drill, a screwdriver, and a caulk.
  2. Lower your chimney cap onto the flue and over the crown.
  3. Fit a power drill with a masonry bit that is 1/8 inch smaller than the installation screws and drill pilot holes into the crown through the holes on the cap.
  4. Remove the cap and run a bead of caulk around the crown’s edges.
  5. Put the chimney cap back in place again, now over the caulk.
  6. Place the installation screws in the pilot holes and tighten them with a screwdriver.

If you follow these steps carefully, installing your chimney cap will be a breeze! However, if you don’t feel safe or confident doing it yourself, you can always call and hire a professional to take care of it for you. By choosing the latter option, you can avoid risking your safety or potentially damaging your home. 

Whether or not you decide to DIY, you’ll want to install a chimney cap before it gets cold outside. Not only will a chimney cap prevent unwanted pests from entering your home, but it will also prevent fires and drafts, reduce moisture, eliminate sparks, and keep your flue clear and free from debris. You can save yourself time and money in the long run by installing a chimney cap today!