how to install a chimney cap

Not too long ago we did a project about installing a Blaze King Fireplace which also required us to install a DuraVent liner. This time we are installing a chimney cap. Installing a chimney cap is not too hard and the tools needed are minimal. Most chimney caps are made to fit your chimney with four screws. You just put the cap on top and tighten the screws. However some chimneys are older and take a little more time to install a cap. For this project, we are putting a chimney cap made for modern homes on an old chimney. As you can see by the pictures below, this chimney doesn't have much of a lip for the screws to hold the cap on tight.

Chimney Caps on Amazon

Having a cap on your chimney is very important for two reasons. First, it stops animals from getting inside and causing an even bigger mess. Second, the cap protects the chimney and the pipes below from the weather, such as rain or snow. Which we know that this can cause rusting in whatever is below such as the furnace, water heater or boiler.

You can pick a cap up at your local hardware store for about $30-$50. You can even get more expenive ones if you have cash to burn. For my cap, I found this on craigslist for about $15. Apparently he tried to rig this up for his chimney and couldn't get it to work, so he bought a different one. Since he drilled extra holes in the cap, he couldn't return it.

Before you start, think safety. Make sure your ladder is set up properly, it's not too windy out, your roof is free of hazards such as ice or tripping hazards. Even though this job really takes one person, it is a good idea to have someone around. That person can hold the ladder for you and just be a second set of eyes. If you fall off the roof or something else happens, they can assist in helping. Once you are comfortable and positive you have taken all the safety measures, you can begin work. Again, this how to is designed for the cap that will not install with the four screws that the manufacturer included. You will have to install this with L- brackets.

Tools needed to install chimney cap

Chimney Cap
4 L-Brackets
4 Sheet metal screws
4 concrete screws
Ladder
Hammer Drill
Drill
Drill bit – Metal & Concrete
Safety gear such as glasses and safety line for when you are on the roof

Steps to install a chimney cap

Even though you already measured your chimney opening and bought the correct cap, it is a good idea to dry fit the cap and make sure it truly will fit and will work.
When the cap is on the chimney as a dry fit, look around and see where you can install the cap screws. If your chimney is like mine, I could only install three screws because the other cap from the fireplace was in the way. Now is a good time to mark where you will attach the L-brackets to the cap and to the chimney top.
Now that you have your markings, head back down off the roof to attach the L-brackets. Use your drill to install the sheet metal screws into the chimney cap. Make sure the bottom of the L-brackets are flush with the bottom of the cap. This way when you install it on your chimney, everything sits flat. Most sheet metal screws will pierce the cap and fasten nicely in place. If you are having a hard time getting this to work, you can use a drill bit and make a pilot hole.
Now that the L-brackets are attached to the cap, grab your hammer drill, concrete screws, concrete bit, chimney cap and head back up the ladder to the top of the chimney.
Place the cap back on the chimney to make sure the L-brackets sit flush with the top of the chimney. Now mark off where you can to drill into the chimney to fasten the cap to the chimney. Now you can remove the cap and drill your holes.
Once your holes are drilled using the concrete bit and hammer drill, you can put the cap back in place.
Use the concrete screws to fasten the cap down.

In reality, using the L-Bracket method, you really only need two screws if you have a tight fit. I used three because of my situtation.