Flue Cap vs. Chimney Cap: What’s the Difference?
Hats off to your caps!
Highlights
The flue is the space that gas and smoke travel through as they exit your home.
All chimneys contain a flue, and some have multiple flues.
Capping the flue or chimney keeps rain, snow, and critters out.
Whether you need a flue cap or chimney cap depends on the type of chimney.
Without a proper chimney covering, rain and snow can get in, falling leaves can build up, and critters can build a nest. To protect your chimney and the rest of your home, you need to install a cap. But what's the difference between a flue cap versus a chimney cap?
Both protect your chimney, but a flue cap only covers the flue, the space that gas and smoke travel through, while a chimney cap covers the entire structure. Learn more about the differences between the two and how to choose the right cap for your home with the help of a chimney professional.
What's the Difference Between a Flue Cap and a Chimney Cap?
One way to understand the difference between a flue cap versus chimney cap is that both cover the flue, but a chimney cap may offer more coverage.
| Type of Difference | Flue Cap | Chimney Cap |
|---|---|---|
| Coverage area | Flue only | Entire chimney |
| Attachment | Slip-in or clamp-on | Top-mount |
| Shape | Rectangle, oval, round | Rectangle |
| Materials | Steel, copper | Steel, copper |
| Measurements | Inside of flue | Entire chimney |
| Cost to install | Lower | Higher |
Flue Cap vs. Chimney Cap
Compare and contrast these two types of caps to find out which one is best for your home’s chimney.
Coverage Area
A considerable difference between a flue cap and a chimney cap is the area they cover. A flue cap protects a chimney's flue. Depending on the type of chimney you have and the type of heating systems in your home, you may have multiple flues in a single chimney.
For example, if you have a fireplace and a furnace, you're likely to have at least two flues in your chimney. You'd need a cap for each one.
You can either put a single flue cap on each flue or use a large chimney or multi-flue cap to cover them. A multi-flue or full chimney cap would cover the entire crown of the chimney.
Attachment Options
A flue cap mounts onto the flue of the chimney. Depending on its style, it may slip into the flue, fitting just inside of it. Another option is for the flue cap to slip over the flue, clamping onto the outer edge. Full chimney caps or multi-flue caps attach to the crown of the chimney. They are typically top-mount and may be attached with an adhesive or with screws.
Shapes
The shape of a flue cap may be different from that of a full chimney or multi-flue cap. Flues can be round, oval, or square/rectangular shaped, and the flue cap will usually correspond to their shape. You could also install a square or rectangular flue cap over a circular flue.
While flues can be round, chimneys are typically rectangular or square-shaped. A full chimney cap is usually four-sided to match the shape of the chimney.
Materials
One thing flue caps and full chimney caps have in common is material types. Typically, a chimney or flue cap is made from:
Aluminum
Copper
Galvanized steel
Stainless steel
Each material type has its benefits and drawbacks. Aluminum and galvanized steel chimney caps are typically the budget-friendly choice, but they are less durable than other options. Both types of metal can corrode easily. Stainless steel chimney caps resist corrosion but cost more than galvanized steel or aluminum. Copper is the priciest pick but also the longest-lasting.
Measurements
The measurements or size of a flue or chimney cap vary considerably based on the type of chimney you have and the type of flue or flues. For flue caps that slip inside a round flue, you need to measure the interior flue diameter. For flue caps that clamp onto an extended flue, which sticks out above the chimney, you need the flue area. For a multi-flue cap or full chimney cap, you should measure the area of the chimney crown and the height of the tallest flue.
How Much Does it Cost to Install a Chimney or Flue Cap?
Size and material affect the cost of a chimney cap, along with whether you do the installation work yourself or not. The average cost of a chimney cap installation is $300. But if you're installing a smaller flue cap or choosing a lower-priced material, you may pay just $75.
DIY vs. Hiring a Pro
Chimney caps cost between $75 to $500 for materials and installation labor, depending on the type and material of the cap. Installing the chimney or flue cap yourself will lower the total cost of this task. However, you risk placing it incorrectly and causing potential damage. Plus, working at high heights is dangerous and best left to chimney professionals.
Installation labor accounts for about 50% of the project cost, so you’ll save about $150 to DIY. Another option is to purchase the chimney or flue cap on your own and hire a chimney professional to install it.
Frequently Asked Questions
If you have a chimney, you need a flue or chimney cap. The right covering keeps rain, debris, and animals from getting into your flue or chimney and causing damage. A flue or chimney cap also provides fire protection. The mesh insert around the cap keeps sparks from flying out of the chimney and igniting leaves and other materials.
Yes, you should cap unused chimneys to prevent damage caused by invasive critters, downdrafts, and moisture build-up. This method of capping a locked-off chimney will properly secure the structure and help maintain its integrity for years to come. Consult a chimney professional about the best type of chimney or flue cap to add to your chimney.
While chimney caps are an essential component of maintaining a safe, long-lasting chimney, they have disadvantages, too. The mesh of the chimney cap clogs easily with creosote, making it more difficult for the necessary oxygen to reach the fire. Chimney caps also develop discoloration and rust stains over time, causing damage to interior chimney walls.