Do I Need a Chimney Cap? (Chimney Safety 101)
To most people, a chimney cap might just look like an aesthetic addition to one’s chimney. However, a chimney cap serves various important functions, the most important of which is providing protection against water damage.
In the following article, we discuss why it is important to get a chimney cap installed, different types of chimney caps, sizing your chimney for chimney cap installation, chimney cap maintenance, and much more. All in all, this article will give you all the information you need regarding chimney caps.
So, let’s start with the basics.
What Is a Chimney Cap?
Sitting on top of a chimney crown is a metal covering called the chimney cap. The cap contains a mesh that allows smoke, Carbon Monoxide (CO) gas, creosote, and other by-products of combustion to escape from the chimney while keeping squirrels, birds, debris, and other unwanted guests outside of it. Over the mesh is a cap that covers the chimney flue opening, keeping rainwater and snow out of it.
Do I Need a Cap on My Chimney?
A chimney can function without a chimney cap. But that doesn’t mean you shouldn’t have one installed.
That’s because a chimney cap plays a paramount role in keeping your chimney functional and increases its life by keeping it protected from water damage, clogging, and rust.
Let’s talk about the benefits and importance of a chimney cap in more detail.
Benefits of Having a Chimney Cap
Prevents Water Damage
Your chimney is a hollow structure with an opening at the top from where smoke and other by-products of combustion can escape. However, water, snow, dust, and a myriad of other things can enter your chimney from the same opening.
If water in the form of rain or snow enters your chimney, it can be disastrous. Water penetration can deteriorate the mortar joints and crack the chimney bricks. This, if not prevented, can lead to structural damage in the form of bricks falling off from inside the chimney.
Also, from these cracks on the chimney bricks, water can even get inside the neighboring walls and cause damage. Apart from that, various chimney parts e.g. chimney damper, firebox, etc. can catch rust which will not only impact their efficiency but also decrease their lifespan.
A chimney cap provides a cover over the chimney that prevents rainwater and snow from the sky above from entering your chimney. Therefore, a chimney with a cap is protected against water and safe from the multitude of problems that it could have caused.
Prevents Clogging
A chimney’s primary function is to provide appropriate airflow, maintain an inflow of outside air (to provide oxygen for burning), and an outflow of smoke, CO gas, etc. That function is hindered if a chimney is clogged.
Since your chimney has an opening at the top, small animals such as squirrels, bats, raccoons, and birds can get inside for shelter. They do so to protect themselves against predators and also a warm place to nest.
These animals, having nested inside your chimney, clog it and prevent the process of airflow. Squirrels have even been known to enter homes through the chimney and ruin furniture and break ornaments.
However, animals are not the only ones to blame, dust and debris also enter the chimney from the top opening and clog it.
Since a clogged chimney has restricted airflow, there’s not enough oxygen for proper combustion. Which makes it harder to ignite a fire. Also, a clogged chimney is dangerous because it doesn’t allow exhaust gasses such as smoke and CO gas to escape.
Smoke and other gasses backdrafting into your home not only ruins your furniture (as soot starts to buildup on it) and causes discomfort but it’s also a serious health concern (CO gas is known to be fatal upon prolonged exposure.)
A chimney cap comes with a steel or copper mesh which keeps small animals, birds, and dust outside, while allowing smoke and other harmful gasses from the chimney to exhaust. Thus, a chimney cap prevents chimney clogging and ensures that your chimney is working efficiently.
Prevents Downdrafts
Downdrafts are problematic, especially if you live in a windy area. Oftentimes the direction of the wind is such that downdrafting occurs. If you’ve got a fire lit, downdrafting can push back the smoke inside the room. But even if the fire isn’t lit, a downdraft is an issue because it brings the outer colder air into the room, decreasing the temperature.
Downdrafting often brings with it dust, debris, soot, etc. all of which not only ruin your living space but are also known to be skin irritants and hazardous to health.
Getting a chimney cap installed is a great solution to downdrafting. That’s because it blocks the winds and, thus, the downward drafts.
Protects Your Rooftop
It’s common for hot embers to hop out of the chimney and fall on the rooftop. As you can imagine, it’s seriously detrimental to the rooftop. If, however, you have a chimney cap installed, your rooftop is protected. Because a chimney cap’s mesh, apart from keeping debris, small animals, and birds from clogging the chimney, also deflects hot embers and keeps them from damaging your rooftop.
Saves Money
Since a chimney cap prevents your chimney from getting clogged and protects against water damage while also protecting your roof against hot embers, it’s safe to say that your chimney cap saves you tons in cash.
Think of it this way, without a chimney cap, you’ll have to deal with water damage, rooftop damage, and deal with a lot of other problems that would require you to spend a lot of money. And we haven’t even talked about all the frustration and hassle a chimney cap saves you from.
Aesthetic Appeal
A chimney cap is not only useful, it’s also aesthetically pleasing and elevates the overall look of your chimney. However, it’s important to choose a chimney cap that goes well with your chimney. For example, a style of cap that goes well with a masonry chimney will not look great on a metal pipe chimney and vice versa.
If you’re big on aesthetics, we’d suggest buying a copper chimney cap, however, it might hurt your pockets.
What are Chimney Caps Made of? (Best Materials for Chimney Caps)
While chimney caps come in a variety of materials, there are a few that stand out because of being the most useful and common for chimney caps. The following table compares the benefits and drawbacks of these materials:
| Chimney Cap Material | Benefits | Drawbacks |
|---|---|---|
| Stainless Steel | Corrosion-resistant and rust-proof Easily bear harsh weather Come with a lifetime warranty Easy to maintain The natural shine of the steel offers a clean look | Expensive |
Copper | Most aesthetic lookCorrosion resistant DurableCome with a lifetime warranty | Expensive (price is twice that of stainless steel caps) Require regular application of protectant and cleaning to retain the natural look of copper |
| Galvanized Steel | Cost-effective | Prone to corrosion Lack durability Lack aesthetic quality |
| Aluminum | Cost-effective Less likely to corrode Offers a decent look | Not durable Likely to bend due to lightweight |
Types of Chimney Caps (Specialized Features)
There are your standard chimney caps, then there are chimney caps that come with some extra features along with the standard features of water prevention, clog prevention, animal prevention, etc.
While you might not need these caps, having one, depending upon your chimney’s condition and requirements can be quite beneficial.
Outside Mount Chimney Caps
If you’ve got a chimney with multiple flues or your chimney crown is not constructed properly, an outside mount chimney cap will be a great choice. Because, unlike regular chimney caps that fit to the crown or the flue of your chimney, these caps go over the chimney crown and attach to the chimney itself.
This gives them the advantage of providing extra cover and protection to your chimney flue. However, since chimneys come in various sizes, these chimney caps usually come in customized dimensions.
Draft-Enhancing Chimney Caps
As the name suggests, these chimney caps are designed to enhance the upward draft inside your chimney and pull out all the smoke.
They do that by increasing the air velocity which decreases the pressure above the chimney. This creates a partial vacuum, creating a pressure difference. So, the smoke inside the chimney (higher pressure) is pulled out into the (lower pressure.)
Some chimneys have a draft problem that needs a bit more than just a simple draft-enhancing chimney cap. For those, an electric draft-enhancing chimney cap usually does the job. The electric fans of the cap allow you to control the drafts for both masonry and prefabricated chimneys. The only downside is that you’ll need to put in a few extra bucks.
Chimney Cap and Damper System
A chimney damper system is an important part of your chimney and a broken chimney damper directly translates to higher energy bills.
So, if you’re buying a chimney cap and your chimney damper system is broken, malfunctioning, or missing altogether, buying a chimney cap and damper combination is a great way to kill two birds with one stone.
A chimney damper that comes with a cap is just like a top-sealing damper system that sits atop your chimney flue and you can operate it through a stainless steel chain or lever that can be accessed from your fireplace.
It’s important to note that chimney cap damper combinations are designed for rectangular or square chimney flues. So, if you’ve got a round or oval shaped chimney flue, you’ll need to purchase a damper system separately.
Flue Stretcher Chimney Caps
Flue stretcher chimney caps, as obvious from the name, increase your chimney flue’s height. This not only looks good but has a utilitarian purpose, as well.
Oftentimes, if you’ve got smoke entering your room when the fire is lit, that’s because your chimney is not taller than your roofline. Because the roof blocks the flow of air to the flue, proper drafting doesn’t occur.
Raising the flue height by a few inches through a flue stretcher chimney cap solves this problem.
What Size Chimney Cap Do I Need?
If you’re looking to buy a chimney cap, you must be aware of the required measurements to make sure the cap completely covers the chimney flue for the best results. Since different chimney types have slightly different measuring procedures, let’s discuss each of them separately:
Single Flue Chimney
If you’ve got a single flue chimney (that’s the most common type) with an extended flue, you need to measure the outer width and the extended length of the chimney flue.
However, if the flue is not extended (the length between the chimney crown and the top of the flue is one inch or less), the measurement depends upon your choice of chimney cap style.
If you want to install a chimney cap with legs/brackets, measure the outer dimensions i.e. width and depth, and choose a chimney cap accordingly. On the other hand, if you want a top mount chimney cap installed, measure the outer length and width of your chimney and flue. Also, measure the flue height.
Now, you can either use a flue mount chimney cap that only covers the chimney flue (since it’ll be smaller in size, it’ll cost less) or you can go for a crown mount chimney cap that’ll cover and protect the whole chimney (but cost more due to a larger size.)
Note: Whether you choose a flue mount cap or a crown mount cap, the height of the chimney cap needs to be 5 inches greater than that of your flue.
Single Flue Chimney (Rounded vs Squared, Rectangular, or Oval)
A chimney with a rounded flue will require a top mount chimney cap. However, it can either be one that can be bolted to the flue or one that slips inside the flue. For the former, the outer diameter needs to be measured; while for the latter, the inside diameter of the flue needs to be measured.
Squared, rectangular, or oval chimney flues require chimney caps that need to be clamped and screwed. Slip-in chimney caps, don’t work with these shapes.
For the dimensions, measure the outside width and length of the chimney flue. Just make sure to buy a cap that is designed to cover the oval dimensions of the chimney flue, completely.
Multi-Flue Chimney
If you’ve got a chimney with multiple chimney flues, you’ll need to get a top-mounted chimney cap. To get the measurements, measure the width and length of the chimney crown, the width and length of the area covering all the chimney flues, and the height of the tallest chimney flue.
Measuring the height is important to ensure the chimney cap height is at least 5 inches greater than all of your chimney flues, to allow for optimum flow of air.
Now, you can either choose a cap size that covers the entire chimney (costly) or one that just covers all the flues (cheaper).
Chimney Cap Mesh Size
Size of the mesh openings of a chimney cap is important because it has to be such that it allows for smoke and other combustion by-products to escape while preventing hot embers to get out of the chimney.
According to the California residential code, the mesh openings should be such that it should block objects with a diameter of more than half an inch while allowing the passage of objects with a diameter smaller than 3/8 inches.
Everywhere else, however, a 3/4 inch mesh opening size is preferred.
Common Chimney Cap Mistakes
If you’re planning on installing a chimney cap on top of your chimney, be mindful of the following mistakes that people commonly make to avoid any issues in the future.
Wrong Measurements
Chimney cap measurements are important for the to provide adequate protection against rain and snow. Make sure you measure your chimney cap according to the guide provided above. Once done, take your measuring tape along while going out to buy your chimney cap. It’ll help you buy a chimney cap with the required measurements.
For example, if you install a chimney cap that’s not 5 inches taller than the chimney flue, it would result in poor drafts.
Wrong Chimney Cap Material
We’ve already weighed the pros and cons of choosing different metals for chimney caps. So, you’re aware of how choosing the wrong material could be detrimental to your chimney cap and the safety of your chimney.
For example, if you’re living in the Southwest or any other dry area, using a galvanized steel chimney cap would be a good choice because it’s cheaper. However, in most of America, the galvanized steel wouldn’t last more than a few years due to corrosion from the elements and deshaping. And even though you could increase its life a bit through regular maintenance, it’s a lot of work.
Stainless steel caps are much better in that regard and require little to no maintenance and last a long time. Chimney caps made from copper are also resistant to rust and last a long time but require maintenance to retain their aesthetic appeal.
Secure Installation
You should be extra cautious when ensuring that the chimney cap is tightly secured. Any loose nuts or bolts could result in your chimney cap flying off and causing serious damage to nearby property.
It’s also important to secure your chimney cap with the hardware that came along with it. Not doing so would lead to potential problems.
For example, stainless steel chimney caps come with stainless steel screws. Using any other screws might initiate electrolysis and freeze the screws.
Not Considering the Damper System
When taking chimney cap measurements, people often forget their dampers. That poses a problem especially if you’ve got a top damper. Therefore, make sure your chimney cap height is such that it allows a 5 in clearance when your top damper is open.
Or, alternatively, you can get a top damper set with a chimney cap included and not worry about the measurements.
Signs That Your Chimney Cap Needs to Be Replaced
Chimney caps have long lives, however, the environmental factors can reduce its life drastically if it’s not regularly maintained. Your chimney caps can corrode and weaken, thus, not providing effective chimney protection. In fact, small animals can tear their way into a weakened chimney cap mesh.
Owing to its position, however, it’s not easy to ensure that your chimney cap is all good and dandy.
So, how do you know it’s time to repair your chimney cap or get a new one altogether? Well, the following signs will let you know
Downdrafts
Imagine, you’re sitting one fine morning minding, your own business. All of a sudden, out of nowhere, a gust of wind enters your room through the chimney. And with it, comes all the rust, debris, and creosote that ruins your interior.
If you’ve got a well-maintained chimney cap, you’ll most likely not face such a scenario. But if you do, the number one guess is that your chimney cap is damaged and needs to be replaced.
Clogged Mesh
If your chimney cap mesh is hanging apart from the cap or is clogged so much that simple cleaning might not do, it’s time to get a new chimney cap. A clogged chimney cap mesh will not let smoke escape from the chimney, as a result, the smoke will enter your home.
Also, a broken mesh will let small animals and birds enter your chimney and clog it. So, whenever you see a heavily clogged or broken chimney cap mesh, don’t wait to buy a new cap right away.
Clogged Chimney Cap Fans
If you’ve got an electric draft-enhancing chimney cap, make sure the fans are running smoothly. It’s common for these fans to get clogged and stop working. If that’s the case, you’ll need to buy a new one as these turbines are quite hard to clean.
Moisture in Your Fireplace
If you notice moisture in your fireplace, it can be due to various reasons such as, a damaged chimney crown, damaged chimney flashing, or a bent or broken chimney cap. Make sure you check all, especially your chimney cap as it is one of the main barriers protecting water from getting inside your chimney.
Storms
If you’ve recently experienced strong winds or a storm in your area, you might want to check if your chimney cap is still secured and safe. If you notice that your cap is gone, bent, or not in the right position, it’s a cause of concern.
No matter how tightly screwed, strong winds can loosen chimney caps and blow them off your chimney. If not, these winds are strong enough to significantly damage or bend your chimney cap.
Rust
Rust is the enemy of almost all chimney parts including your chimney cap. If there are signs of corrosion and serious amounts of rust on your chimney cap, it’s time for a replacement. Rust can weaken your chimney cap and it’s only a matter of time before small animals will be able to tear it off and enter your chimney.
Chimney Cap Maintenance
To prevent your chimney cap from catching rust or getting damaged, its maintenance is of utmost importance. Here’s how to maintain your chimney cap:
Use Seasoned Wood
Like your chimney, your chimney cap also gets plagued with creosote deposits that clog and deteriorate the chimney cap mesh. Creosote is a by-product of poor combustion which occurs either due to poor airflow (lack of oxygen) or the use of unseasoned wood.
Unseasoned wood has moisture that produces black smoke that contains by-products of combustion when burnt. Creosote is made from these combustion by-products.
Since seasoned wood doesn’t have much moisture, it produces little creosote.
Pro Tip: When burning fire, stack the logs to allow for air to flow between them. This will produce a hotter fire that will consume more wood, reducing the chances of creosote production.
Regular Cleaning
While using seasoned wood would considerably reduce the creosote deposits, they’ll still be present. So, regular cleaning of your chimney cap mesh is important so that the creosote deposit and debris can be removed from the mesh to unclog it.
To do that, you’ll have to climb up to the roof and see if you’ve got access to the mesh. If so, you can use a wire brush to remove the creosote and debris. However, if you cannot safely reach the chimney cap mesh, it’s best to call professional help.
Chimney Cap Cost
The cost of a chimney cap depends mainly upon three things:
- Material
- Type
- Size
For example, a stainless steel cap would cost more than a galvanized steel cap. Similarly, a basic chimney cap will cost less compared to a draft enhancing chimney cap. Other factors such as customized sizing, specialized functionality, and ease of access to the chimney also contribute to the pricing.
Sometimes, there’s also a need to repair the chimney flue or crown, which also adds to the overall cost of the chimney.
However, to give you an idea, we have put together a table estimating the cost of different types of chimney caps and their installation.
| Chimney Cap | Low Estimate | High Estimate |
| Galvanized steel | 50 USD | 300 USD |
| Aluminum | 60 USD | 200 USD |
| Stainless steel | 70 USD | 500 USD |
| Copper | 200 USD | 1000 USD |
Note: If you require a specialized chimney cap, add around 30% of the original cost, as provided in the table above.
Chimney Cap Installation Cost
The installation cost usually depends upon the chimney cap type, ease of access to the roof, etc.
While you can install a chimney cap on your own, it’s best left to experienced professionals. That’s because they’ll ensure that all measurements are accurate, the screws and bolts are fastened tight, and, most of all, they’ll have the required tools and protective gear to do the job safely and accurately.
A DIY project would cost you around 100 USD. However, if you go with professional help: a chimney sweep would charge you around 130 USD, whereas a fireplace company would charge 170 USD for the installation.
It’s important to note that a chimney cap replacement would always cost 50 to 100 USD more than simple installation. The extra cost is added because of the time and effort required to extract the old chimney cap.
The Takeaway
If you don’t have a chimney cap installed, your chimney is at risk of water damage and getting clogged. You’re also putting your rooftop at risk of getting damaged from the hot embers coming out from the chimney.
A chimney cap solves all these issues and more.
But, chimney caps come in various shapes, sizes, and materials. And it’s important to understand which chimney cap would best suit the needs of your chimney. Since chimneys also come in different shapes and sizes, measurement of your chimney top is important to get a chimney cap that’ll fit perfectly, providing maximum protection.
Once the right kind of chimney cap is installed accurately atop your chimney, you should be good for a long time, provided that you lookout for signs of damage and don’t neglect regular maintenance and cleaning.
However, all good things come to an end. So, if it’s time to get your chimney cap replaced, it’s better to call a professional service than to do it on your own. Not only will you put yourself at risk but you might also damage your chimney or don’t secure the cap accurately.
But remember, when hiring a professional service, make sure you ask for certifications (e.g. CSIA certification) and a valid business liability insurance policy.