A Comprehensive Guide to Chimney Chase Covers

A chimney chase cover on top of a prefabricated chimney with white siding against a white background

Fireplaces are great for warming your home or creating some nice ambiance. But if they aren’t built with adequate protection, they can become an easy entry point for rain, snow, and even local animals like squirrels and raccoons to cause damage.

Thankfully, there are plenty of barriers to help keep these nuisances out of your chimney. One of them that proves popular (especially on newer homes) is the chimney chase cover.

But what are these covers, anyway? What are they made of? And how do you know which size to get?

At HY-C, we’ve manufactured hundreds of chimney chase covers in the past few years, and we want to share what we know with you.

In this guide, we’ll cover everything you need to know about chimney chase covers. By the time you’re finished, you’ll know what they are, whether or not you need one on your chimney, and how to measure for a chase cover to ensure you get the right size.

What Is a Chimney Chase Cover?

A chase cover is a pan-like metal sheet with a hole (or multiple holes) cut out of it. Chase covers usually adorn prefabricated chimneys on newer homes. These chimneys come with a metal chimney pipe that starts above the firebox, goes up through the chimney, and comes out of a hole in the chase cover.

The job of a chimney chase cover is to keep weather and wildlife out of a chimney. They act as a kind of cap for the body of a prefabricated chimney, preventing rain from leaking in or critters from building their nests in your chimney.

Differences between a Chimney Cap and a Chimney Chase Cover

A masonry chimney with a cap on its clay flue pipe next to a prefabricated chimney with a chase cover, both against a white background

In a traditional brick chimney, the job of a chase cover is performed by the chimney crown. The crown is made from concrete and rests over the top layer of brick. A clay flue pipe (or multiple clay flue pipes) protrude from the crown, and a chimney cap covers the clay flue.

A prefabricated chimney uses a chase cover to protect most of the surface area of the chimney. A circular cap is put in place over the metal chimney pipe and operates similarly to a masonry chimney cap. Finally, a storm collar is installed where the chimney cap and chase cover meet to seal any remaining gaps.

What Are Chimney Chase Covers Made Of?

Chase covers are made primarily of two types of metal:

  • Galvanneal
  • Stainless steel

Galvanneal is a good chase cover cap material in the mid to short term. It resists weather and corrosion very well, but it is eventually susceptible to rust. A rusty chase cover will crack, allowing rainwater to leak into the chimney, potentially causing more damage.

Stainless steel, on the other hand, is a much more durable chimney chase cover material. It’s dense, strong, and highly resistant to rust and other types of corrosion. It’s especially useful in coastal areas as it’s resistant to abrasion from saltwater.

At HY-C, around 15% of the chase covers we make are made from 22-gauge galvanneal. The other 85% are made from the longer-lasting (albeit more expensive) 22-gauge 304 stainless steel.

What Sizes do Chimney Chase Covers Come In?

This is a tough question to answer. While chimney caps come in common, stock sizes, chase cover sizes vary widely. Most chase covers are special-made to fit prefabricated chimneys that themselves tend not to come in common, consistent sizes.

That said, of the chase covers we’ve made at HY-C, a not-insignificant amount of them measure either 27” x 27” or 35” x 35”.

Even with that in mind, it’s likely that you’ll have to measure your chimney to find the correct chase cover size for your home.

How to Measure a Chimney Chase Cover

You can’t measure a chimney chase cover without first knowing the number of holes you’ll need in the cover (i.e., the number of flue pipes that need to fit into it). Typically, a chase cover will have either one, two, or three holes in it. We’ve found that:

  • 89% of chase covers will need 1 hole
  • 9% of chase covers will need 2 holes
  • 2% of chase covers will need 3 holes

Start by checking your chimney for the number of metal flue pipes it has. One flue pipe will necessitate one hole, two flue pipes will necessitate two holes, etc.

From there, you’ll need to take a few measurements:

A guide demonstrating how to measure a single-hole chimney chase cover
  1. The length of your chimney
  2. The width of your chimney
  3. The distance between all four sides of your chimney and the edge of the flue pipe

These measurements will help the manufacturer tailor-make a chase cover that will fit your chimney (and its flue pipe(s)) perfectly. The process is very similar for chase caps with two holes. Just measure:

A guide demonstrating how to measure a double-hole chimney chase cover
  1. The length of your chimney
  2. The width of your chimney
  3. The distance between all four sides of your chimney and the edge of flue pipe 1
  4. The distance between all four sides of your chimney and the edge of flue pipe 2

The last thing to consider is the height of the chase cover’s skirt:

A diagram indicating how to find the height of the skirt of a chimney chase cover

The skirt is the metal flange that holds the cover snuggly to the chimney. It needs to be long enough to cover all four edges of the chimney while also providing enough surface area for bolts to penetrate the skirt and attach to the chimney securely.

Most chase cover skirts will measure two, three, or four inches in height. Of the covers we’ve manufactured through the years, we’ve found that:

  • 4% of chase covers have a 2” skirt
  • 68% of chase covers have a 3” skirt
  • 28% of chase covers have a 4” skirt

Three inches is essentially the industry standard for chase cover skirts and will work well in the majority of cases.

Do You Need a Chimney Chase Cover?

It should be clear by now that there’s a lot involved in finding the right chase cover. From materials to sizes and the right number of holes, there are a lot of factors to consider.

But what does this mean for you? Do you need a chase cover on your chimney?

If you have a masonry chimney with a crown, the answer is no — the crown does the work of the chase cover (but you should make sure your clay flue has a chimney cap). If you have a newer prefabricated chimney, though, a new cover may be in the cards.

In most cases, people in need of a new chase cap are looking to replace their old one. If yours is rusty, loose, or otherwise damaged, replacing it as quickly as possible can save you from massive repair bills caused by water or wildlife damage.

You can utilize the HY-C chase cover order form to find and order the perfect chase cover for your chimney. But whether you buy a chase cover from us or another manufacturer, the most important thing is to keep your chimney covered, your flue watertight, and your home secure.

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