Around 90% to 95% of chimneys out there use a standard-sized chimney cap. For the select few whose chimney or flue don’t fall within the standard size ranges, though, finding a cap can be daunting. You may not know which options are available to you, or even which manufacturers offer custom covers.

Having made thousands of custom caps over the years, we’re no stranger to dealing with non-standard chimney dimensions at HY-C. We work with customers all the time to handcraft a precise cap to match the specific dimensions of their chimney.

So whether you’re looking for a single-flue cap, a multi-flue cap, a stainless steel style, or an elegant copper cover, in this guide, we’ll outline the types of custom chimney caps we offer. You’ll understand the styles we have available, the materials they come in, and how to measure for your own custom cap. When you’re done, you’ll be well-equipped to make an educated buying decision and to find the right custom-made chimney cap for your home.

HY-C’s Custom Chimney Cap Styles

We manufacture two different kinds of custom chimney caps at HY-C: custom brand-around caps, and custom skirt-type caps. The custom band-around cap is available in stainless steel only, and the skirt-type caps are available in copper or stainless steel. The style of a custom-skirt cap will differ depending on which metal you choose.

Custom Band-Around Stainless Steel

Our band-around (or band-around-brick) gets its name from the metal band on the bottom of the cap. This band wraps around the top row of chimney brick and clamps down via the bolts on the corners of the cap. This installation method means you don’t have to drill any holes directly into your masonry; the clamping force of the band holds the cap in place.

These custom-made band-around-brick chimney caps are made completely from 304 stainless steel. The maximum base size for these caps is 48” x 96” (or four feet by eight feet). Their large range of available sizes should fit just about any chimney size with no problem.

How to Measure for a Custom Band-Around Chimney Cap

When measuring for a custom band-around-brick chimney cap, there are two measurements you need to take: the dimensions of the top row of chimney brick, and the height of your chimney flue.

The measurement of the top row of chimney brick will determine the lengths of the base, mesh, and hood of your custom band-around cap. In the example above, the dimensions of the top row of chimney bricks are 36.5” x 24.5” x 36” x 23”.

The second measurement, the height of your chimney flue, determines the height of the mesh and braces of your cap (braces are the lengths of metal inside the cap that hold the entire apparatus together). From the example above:

• A flue of 3.5” in height or less will use 9” braces and mesh
• A flue between 3.5” and 6” in height will use 12” braces and mesh
• A flue between 6” and 9” in height will use 15” braces and mesh
• A flue between 9” and 12” in height will use 18” braces and mesh

Providing these measurements will allow us to know precisely how to build your custom cap to fit the exact dimensions of your chimney.

Custom Skirt-Type (Stainless Steel)

A custom skirt-type chimney cap differs from a band-around-brick cap in that it bolts directly into the chimney’s top row of brick. The addition of the metal skirt provides the best possible protection against rain, snow, sleet, hail, wind, and other elemental forces that degrade a chimney over time.

Like the band-around-brick cap, this skirt-type chimney cap is also made of 100% 304 stainless steel, and its maximum base dimensions (like the band-around-brick style) are 48” x 96”.

How to Measure for a Custom Skirt-Type Stainless Steel Chimney Cap

Like the band-around-brick custom chimney cap, you’ll need two sets of dimensions when measuring for a custom skirt-type stainless steel chimney cap: the dimensions of the top row of chimney brick, and the height of your chimney flue.

The lengths and widths of the top row of chimney brick will determine the length and width of your custom band-around cap. In the example above, these dimensions are 36.5” x 24.5” x 36” x 23”.

The measurement of the height of your chimney flue will determine the height of the braces and the mesh on your custom skirt-type cap. As you can see in the example above:

• A flue of 5” in height or less will use 8” braces and mesh
• A flue between 5” and 8” in height will use 12” braces and mesh
• A flue between 8” and 11” in height will use 15” braces and mesh
• A flue between 11” and 14” in height will use 18” braces and mesh

There should be at least 6” of space between the top of your flue and the hood of the chimney cap to allow smoke to vent out properly. Knowing the flue height will help us know what the height of the cap should be to allow for this ventilation.

Custom Skirt-Type (Copper)

Copper is the pinnacle of luxury and style in the world of chimney caps. The elegant, eye-catching metal is a bit softer than stainless steel, but it still provides adequate weather and animal protection.

Copper also acquires a natural patina over time as it’s exposed to the elements — a much sought-after aesthetic feature of a copper chimney cover. Bear in mind that copper chimney caps carry a much higher price than stainless or galvanized steel.

Like its stainless steel counterpart, a custom skirt-type copper cap is bolted directly into your chimney brick for maximum security. Unlike its stainless steel counterpart, though, a copper custom skirt-type cap does not come with braces; it’s held together solely by its mesh.

You’re a little more limited in the size department with this style of chimney cap, too — the maximum possible base size for our copper custom skirts is 38” x 88” (as opposed to the stainless steel styles’ 48” x 96”).

How to Measure for a Custom Skirt-Type Copper Chimney Cap

Again, you need two all-important measurements when sizing up your custom copper skirt-type cap: the dimensions of the top row of chimney brick, and the height of your chimney flue. In the above example, these dimensions clock in at 36.5” x 24.5” x 36” x 23”.

These copper caps are a bit more limited with regards to flue height, as well. From the example, you can see that:

• A flue of 5” in height or less will use 9” mesh
• A flue between 5” and 8” in height will use 12” mesh
• A flue between 8” and 10” in height will use 14” mesh

The same stainless steel custom-skirt chimney caps can accommodate a maximum flue height of 14”, but the copper cap can only fit flues up to 10” high. This is because the biggest standard size for copper mesh is 14” (as opposed to stainless steel’s maximum height of 18”).

Which Custom Chimney Cap Should You Get?

The world of custom chimney caps is overwhelming. You may have come to this article wondering if you even need a custom chimney cap, what your options are, which size to choose, or which material is right for you.

Now, you know the two types of custom chimney caps we make, which materials we make them in, how those materials may affect the possible size of the cap, and what kind of measurements you need for your custom cap.

If you’re ready to pull the trigger on a custom chimney cap, our customer service team is ready to help. All you’ll have to do is mention which type you want, your preferred material (if you’re after a skirt-type cap), and the dimensions of your chimney brick and flue. From there, the rest is in our hands, and your custom-made HY-C cap will be ready for your roof in no time.

A chimney cap serves a humble role. It sits securely atop your chimney, keeping out rain, hail, snow, and even critters. It does its job passively but unceasingly, its sturdy metal frame bolted tightly onto your chimney, braving the elements season after season.

Most people don’t think or know much about their chimney cap. After all, they can last well over 50 years, and homeowners generally only have to consider them in a select few circumstances:

1. When building a new home
2. After a problem is discovered with their existing cap
3. When replacing a cap purely for aesthetic reasons

Because they’re the type of thing you don’t buy often, people tend to have a lot of questions about chimney caps when they actually do have to think about them. One of the most important ones to consider while shopping around is, “Can I buy a standard chimney cap, or do I need a custom-made chimney cap?”

Well, we’ve been making chimney caps at HY-C for over 75 years. In fact, our factory floor is no more than a few yards from where this very article is being written. We make a few dependable lines of standard caps, and we also take custom chimney cap orders all the time. We know how to make them, who needs them, and everything in between. And we want to teach you all about it.

In this guide, we’ll cover everything you need to know about chimney cap sizes. Whether you’re looking for a 5” x 9” rectangular single-flue cap or a multi-flue custom-skirt copper cap, by the time you’re done, you’ll know how chimney cap sizing works, and you’ll understand whether or not you need a custom chimney cap on your home.

Which Standard Sizes Do Chimney Caps Come In?

Think about chimney cap sizes like shoe sizes: when you shop for shoes, do you expect to have to special order them? Probably not — shoes are made in specific, incremental sizes, and unless you have especially small or big feet, the standard sizes will probably work for you.

Chimney caps basically work the same way. Manufacturers make chimney caps in very particular sizes, and we do that because those standard sizes fit most chimney flues around the country. In fact, one of our company owners estimates that 90% to 95% of the chimney caps we sell are standard-sized caps.

Put simply, the only situation in which you’ll need a custom-made chimney cap (outside of aesthetic reasons) is when your chimney flue or crown doesn’t fit within the standard flue or crown size ranges. So in order to understand whether you need a custom cap or not, learning about the standard sizes is a great place to start.

Chimney caps fall into one of four categories:

1. Single-flue square/rectangular bolt-on
2. Single-flue round bolt-on
3. Single-flue round slip-in
4. Multi-flue

Each type of chimney cap has its own size range, and it’s very likely that your chimney flue (or crown, in the case of a multi-flue cap) falls within the standard size ranges.

Single-Flue Square or Rectangular Bolt-On Chimney Cap Sizes

The bulk of the chimney caps on the market connect directly to your flue tile (the brown pipe that protrudes from the concrete chimney crown). They make this connection one of two ways: they bolt onto the tile or they slip into the tile.

Square or rectangular chimney caps designed to bolt onto a single, square- or rectangular-shaped flue come in a range of sizes. The following table contains standard chimney cap dimensions and the flue sizes on which they fit.

If you have a square or rectangular flue whose dimensions are within the following range, you don’t need a custom chimney cap:

Single-Flue Round Bolt-On Chimney Cap Sizes

If your chimney flue is round instead of square or rectangular, don’t worry — there are standard chimney caps for you as well. Instead of length and width measurements, though, the cap you need will depend on the diameter of your chimney flue.

The table below will help you to find the chimney cap diameter you need based on the diameter of your round chimney flue. If your flue is within this range, you don’t need a custom chimney cap:

Single-Flue Round Slip-In Chimney Cap Sizes

Not all customers want or need a bolt-on chimney cap. For this reason, manufacturers design round caps that slip into the chimney flue instead of being bolted on. The installation process is much easier; you just slide the legs of the cap into the flue, and they’re held in place by tension.

Despite the installation method varying, round slip-in caps essentially fit the same flue sizes as round bolt-on caps (with one additional smaller size available). If your flue has a diameter within this range, you don’t need a custom chimney cap:

Multi-Flue Chimney Cap Sizes

Multi-flue chimney caps are quite a bit different than single-flue caps. Installers screw these caps directly into the chimney’s crown — the concrete slab poured on top of the masonry and around the flue tiles.

These caps are measured in screen-to-screen dimensions, but it’s important to note that they come with flanges on all four sides of them — metal edges that are perpendicular to the chimney cap’s mesh screen.

The flanges on our multi-flue chimney caps come with pre-drilled holes to make them easier to install. The flanges themselves measure 1.25 inches, meaning they add a total of 2.5 inches to the screen-to-screen length and screen-to-screen width of the cap (since there are two on each side).

The following table lays out both the screen-to-screen and flange-to-flange dimensions of our multi-flue chimney caps. If the dimensions of your multi-flue chimney’s crown fall within any of the ranges on the table, you don’t need a custom chimney cap:

What if Your Chimney Falls Outside the Standard Size Ranges?

Before now, you probably knew very little about chimney caps, let alone how to measure one. As you can tell, though, it’s pretty easy: just figure out which one of the four categories your chimney falls into, and check to see whether or not its dimensions can accommodate a standard chimney cap. If you’re like 90% to 95% of people out there, a standard cap will work for you.

If your flue or crown falls outside of the standard dimensions, though, you’ll probably need to purchase a custom chimney cap. If that’s the case, you’re in luck: we make custom-sized chimney caps all the time.

Wondering how to get started? Our customer service team can help you figure out what style, color, and dimensions you’ll need for your custom chimney cap based on your current chimney flue or crown. Reach out today to find the perfect chimney cap for your home.