Do I Need a Chimney Cap? (Chimney Safety 101)

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To most people, a chimney cap might just look like an aesthetic addition. However, a chimney cap serves important functions, the most vital of which is protecting against water damage.

If you are wondering, “Do I need a chimney cap?” we’ve got you covered.

Let’s look at 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.

What Is a Chimney Cap?

Sitting on top of a chimney crown is a metal covering called the chimney cap. The cap contains 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.

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. 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.

Benefits of Having a Chimney Cap

Here are the key benefits of having a chimney cap:

Prevents Water Damage

Your chimney is a hollow structure with an opening at the top. That’s how smoke and other by-products of combustion escape. However, water, snow, dust, and a myriad of other things can enter your chimney through 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 can lead to structural damage in the form of bricks falling off from inside the chimney.

Water can even get inside the neighboring walls and cause damage. Various chimney parts, such as the chimney damper, firebox, and more, can suffer from rust, which will not only impact their efficiency but also decrease their lifespan.

A chimney with a cap is protected against water and safe from the multitude of problems it could cause.

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, and the like. 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 to find a warm place to nest.

These nests can clog the chimney and prevent proper airflow. Squirrels have even been known to enter homes through the chimney and ruin furniture or break things.

However, animals are not the only problems with clogging. Dust and debris can also enter the chimney from the top opening and clog it over time. 

Since a clogged chimney has restricted airflow, there’s not enough oxygen for proper combustion. That makes it harder to ignite a fire. A clogged chimney is dangerous because it doesn’t allow exhaust gasses such as smoke and CO to escape. 

Smoke and other gasses back-drafting into your home not only ruins your furniture (as soot starts to build up 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 steel or copper mesh that keeps small animals, birds, and dust outside while allowing smoke and other harmful gasses from the chimney to exhaust.

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 the smoke back inside the room. But even if the fire isn’t lit, a downdraft is an issue because it brings colder air into the room, decreasing the temperature.

Downdraft often brings with it dust, debris, and soot, all of which not only ruin your living space but are also known to be skin irritants and health hazards.

A chimney cap 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. Apart from keeping debris, small animals, and birds from clogging the chimney, a chimney cap’s mesh also deflects hot embers and keeps them from damaging your rooftop.

Saves Money

Since a chimney cap prevents your chimney from getting clogged and stops water damage while also protecting your roof against hot embers, it’s safe to say that your chimney cap saves you tons in cash.

Without a chimney cap, you’ll have to deal with water damage, rooftop damage, and many other problems that would hit your pocketbook. And that doesn’t include all the frustration and hassle a chimney cap saves you from!

Aesthetic Appeal

A chimney cap is 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 (but it might hurt your wallet!).

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. The following table compares the benefits and drawbacks of these materials:

Chimney Cap MaterialBenefitsDrawbacks
Stainless Steel* Corrosion-resistant and rust-proof

* Easily bear harsh weather

* Comes with a lifetime warranty

* Easy to maintain

* The natural shine of the steel offers a clean look
* Expensive

* Most aesthetic lookCorrosion resistant

* DurableCome with a lifetime warranty
* Prone to corrosion

* Lack durability

* Lack of aesthetic quality
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 its lightweight

Types of Chimney Caps (Specialized Features)

There are your standard chimney caps, then there are chimney caps that come with some extra bang for your buck. While you might not need these caps, having one could 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. 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 for your chimney flues. 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. The smoke inside the chimney (at higher pressure) is pulled outside (to 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, a broken chimney damper directly translates to higher energy bills.

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. You 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. If you have 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.

Sometimes, if you’ve got smoke entering your room when the fire is lit, it might be because your chimney is no 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 have proper measurements to make sure the cap completely covers the chimney flue. Different chimney types have slightly different measuring procedures.

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 ( the 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, as well as the flue height.

You can use a flue mount chimney cap that only covers the chimney flue, or you can go for a crown mount chimney cap that’ll cover and protect the whole chimney. Since the flue mount chimney cap is smaller in size, it’s the more affordable option. 

Note: Whether you choose a flue mount cap or a crown mount cap, the height of the chimney cap needs to be 5 inches taller 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; for the latter, measure the inside diameter of the flue.

Square, 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. Make sure to buy a cap designed to completely cover the oval dimensions of the chimney flue.

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 proper size, 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 taller than all of your chimney flues. This allows for optimum flow of air.

Now, you can either choose a cap size that covers the entire chimney or one that just covers all the flues. One that covers the entire chimney will cost a bit more.

Chimney Cap Mesh Size

The size of the mesh openings of a chimney cap must allow for smoke and other combustion by-products to escape while preventing the release of hot embers.

According to the California residential code, the mesh openings should block objects with a diameter of more than 1/2 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 these common mistakes.

Wrong Measurements

Chimney cap measurements are important 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 to double-check your purchase.

Wrong Chimney Cap Material

You’re already 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 the United States, galvanized steel wouldn’t last more than a few years due to corrosion from the elements and reshaping. 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. They require little to no maintenance and last a long time. Chimney caps made from copper are resistant to rust and last a good while but require maintenance to retain their aesthetic appeal.

Insecure 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 comes along with it. Not doing so could 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-inch clearance when your top damper is open.

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, but environmental factors can reduce that lifespan dramatically if you don’t regularly maintain the cap. Owing to its position, however, it’s not easy to ensure that your chimney cap is all good and dandy.

How do you know it’s time to repair your chimney cap or get a new one altogether?


Imagine sitting in your home one fine morning, just minding your business. Suddenly, out of nowhere, a gust of wind enters your room through the chimney. And with it comes rust particles, debris, and creosote that ruin your interior.

If you’ve got a well-maintained chimney cap, you’ll most likely never face such a scenario. But if it ever does happen, 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 cap. Clogged 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 they can easily block it as they try to nest. So whenever you see a heavily clogged or broken chimney cap mesh, don’t wait. 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 or flashing or a bent or broken chimney cap. Make sure you check all these things, especially your chimney cap, as it is one of the main barriers protecting your chimney from water infiltration.


If you’ve recently experienced strong winds or a storm in your area, you might want to make sure 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 cause for concern.

No matter how tightly affixed, strong winds can loosen caps and damage them or simply blow them right off your chimney.


Rust is the enemy of almost all chimney parts. 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 rusting or sustaining damage, 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 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 smoke contains by-products of combustion. 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 airflow 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. Regular cleaning of your chimney cap mesh is important so that the creosote deposit and debris can be removed.

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 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 a need to repair the chimney flue or crown, which adds to the overall cost.

To give you a rough idea of costs, we have put together a table estimating the cost of different types of chimney caps and their installation.

Chimney CapLow EstimateHigh Estimate
Galvanized steel50 USD300 USD
Aluminum 60 USD200 USD
Stainless steel70 USD500 USD
Copper 200 USD1000 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, and more.

While you can install a chimney cap on your own, it’s best left to experienced professionals. 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

To answer your question, “Do I need a chimney cap?” 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.

Chimney caps come in various shapes, sizes, and materials. Accurate 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 atop your chimney, you should be good for a long time, provided that you look out for signs of damage and don’t neglect regular maintenance and cleaning.

However, all good things come to an end. 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 not secure the cap properly.

When hiring a professional service, make sure you ask for certifications (e.g., CSIA certification) and a valid business liability insurance policy.

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