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The Home Depot

Chimney Cap Installation Guide

Pro Referral > Home Guides > Fireplace & Chimney > Chimney Cap Installation Guide
Chimney Cap Installation Guide

Have you ever awoken and found that there was a squirrel sleeping in your favorite chair? Or the last time it rained, your living room fireplace was drowned by water?


You probably need to fix or reinstall your chimney cap. There are many different kinds of these accessories, but it all boils down to a trio of specific types. The design may change, but you’ll likely encounter only one of these three to keep undesirables from tumbling down the chimney.


A single flue cap is installed when the actual chimney flue is taller than the chimney. Crown mounted caps are for flues that are flush with the top of the chimney. They can also be employed when there is more-than-one chimney. Lastly, the inside mount cap will be found on a square or round chimney flue.


Now that you have an idea of the different devices, are you sure you want to crawl up on a ladder and tempt your insurance policy as you bounce down to Terra Firma?

  1. A single flue cap is installed when the actual chimney flue is taller than the chimney.

    1. Tools You'll Need

    It looks like you’re going to handle this one without enlisting the help of a pro. Here’s what you’re going to need other than simply a stairway to heaven. Pull out your drill, masonry drill and screwdriver bits, masonry screws, a screwdriver, and some silicone caulk.

  2. 2. Installing a Round Chimney Cap

    Take a good look at the flue. You’re seeking evidence of corrosion. If you find any, treat it before you go further.


    Assuming that everything is A-OK, take your replacement inside mount cap and push it into the chimney flue. Is the chimney flue is made of metal? Don’t apply any caulk. But all other materials will need a strip of goo along the chimney cap seam.

  3. 3. Installing a Single Flue Chimney Cap

    Once again, see if there’s any flaking, rust or other types of corrosion. Same as above. Treat it.


    Align the cap over the chimney flue and fit it into the flue. Position the holes. Using sheet metal screws fasten the cap tightly to the foundation. Hit the seam with silicone caulk to seal moisture out.

  4. 4. Installing a Crown Mount Chimney Cap

    Same drill as the other two. See any corrosion? Take care of it. Set the crown mount cap on the chimney and tighten the flanges around the cap. You want it so they are snugly kissing the chimney. Trace around the edges of the flanges with a dark magic marker. Remove the crown mount chimney cap for the time being.


    Slather a generous blob of all-weather adhesive to the bottom of the chimney cap flanges. Return the unit to the area you traced with the magic marker. Press it back into its previous position.


    You have the option of either attaching the masonry screws or not. The manufacturer will guide you as to whether this is necessary.


    If it is, make some pilot holes into the chimney through the flanges. Drill the holes about one-foot apart. If the unit isn’t that big, simply slap one in the middle of the flange.


    We kept talking about how you might encounter corrosion as you do this project. Any evidence means you need to bring in a pro to inspect the situation soon.


    Finally, be careful as you descend the ladder. Unlike what we alluded to at the beginning, you won’t actually bounce as you hit the ground. It’s more like a “splat.”

  5. 5. Chimney Cap Installation Service

    Do you need help with your project? Contact a Chimney Cap Installation Pro today. Every one of our pros are background checked, licensed and insured so that you can hire with confidence. Read the customer reviews, credentials, and business profiles of all of our pros, and let a qualified professional turn a difficult project into a completed one.

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