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What is Chimney Flashing?

Learn more about the chimney flashing, how it affects the integrity of your roof, how to install it, how to maintain it and its different types.

A close look at a red brick chimney with flashing.

If there’s one thing people notice, it’s a fireplace. You can decorate for the holidays, show off your favorite family photos, and pretty much just sort of lord it over your friends that yes, you do have a fireplace. Everyone always wants a fireplace until they have a chimney.

Then, you start to learn a few things about what it takes to keep your roof and your chimney living in harmony together. That journey begins and ends with chimney flashing. If you’re going to have a fireplace then you need to know what it is, what it does, and how it’s going to matter in your life from the moment you start owning a fireplace.

Related: DIY Roof Repair | Parts of a Roof Gutter | Alternatives to Gutters | Parts of a Roof | Types of Chimneys

What Does Chimney Flashing Do?

If you see it, chimney flashing really doesn’t look like much. It’s actually just a piece of metal. But it does play a pretty big role. Chimney flashing is pieces of metal that are installed at the area where the chimney of a fireplace meets the roof. This metal prevents any moisture from getting between the roof and the chimney, which would then get into your home. That’s huge. So now you see that these little pieces of metal are extremely essential.

However, it’s important to know that chimney flashing is not perfect. Over time, chimney flashing will wear out and it will need to be replaced. The flashing may lift up or begin to rust. Pieces may break off. Anything could happen that may damage or otherwise compromise your chimney flashing. That’s why you need to know how to maintain it and what to do when you need to repair it.

How to Install Chimney Flashing

A man on the roof of the house installing chimney flashing.

Chimney flashing is made with two metal panels. Base flashing is installed first. This is placed beneath the roof shingles. It’s bent into an L shape to fit into the corner where the chimney meets the roof. The second piece of flashing is installed on top of the first. This is the counter flashing. After it’s bent down over the base flashing, it is embedded into a chimney mortar joint.

It sounds simple when you read instructions, but installing chimney flashing is actually a pretty precise process that really does require expertise. You want to use the services of a professional roofer to have chimney flashing installed the right way. Because remember, any little leak is a huge problem that can cause all kinds of damage to your home.

Leaks around the chimney can lead to structural damage. That’s an extremely serious problem and it’s one you never want to have. Moisture can cause your wood to rot. It can damage electrical systems, destroy drywall, and cause a lot of nightmares.

You can install your own chimney flashing if you’ve got the tools and expertise needed to do so. You’ll need to have a roof harness, a grinder, roof brackets, and all the flashing, of course. But you’ll also need a diamond blade for dry cutting, which is something that most casual DIYers do not have. It’s always best to get a professional if you want to install roof flashing.

Types of Roof Flashing

Flashing can be made from all sorts of different metals. The type of metal used to make flashing typically varies by region. In southern climates, which are hot and humid, galvanized steel and aluminum are common. Copper is also an option, but it’s one of the more expensive flashing options available so many people do not choose this. Talk to a professional roofer about the best type of flashing for your region.

How to Maintain Chimney Flashing

This is a close look at a red brick chimney with flashing.

Make a habit of visually inspecting your chimney flashing at least twice a year. That means actually climbing up on the roof and checking all around the chimney to look for any signs of breaks or cracks. Check to find out if the flashing is loose anywhere. Always use caution when you’re on the roof. Work with a buddy and take all safety precautions possible. You should also visually inspect your flashing after violent storms, heavy winds, and other extreme weather.

Flashing is usually sealed with caulk as it’s installed. You can always re-caulk the area around your flashing once or twice a year to help prevent leaks and wear. If your flashing is loose, apply roofing cement on the underside of the flashing and then secure the flashing with masonry nails or screws. Cover all exposed nail or screw heads with roofing cement. This is a relatively easy fix for a loose piece of flashing.

If you notice a bigger flashing problem, such as a piece of flashing that is missing or severely damaged, you’ll want to get a roofer to make the necessary repairs.

Don’t miss an opportunity to update your chimney flashing. For example, if you’re having your roof re-shingled, go ahead and have your chimney flashing replaced, too.

Do You Need Chimney Flashing?

This is a white chimney with flashing on a red tile roof.

Is roof flashing a necessity? Most roofers will tell you yes. Anything that can help to prevent water damage and keep your home safe is something you should have. It’s a relatively small investment to make. Roof flashing itself is not expensive, but it isn’t easy to install.

You will pay more for the labor to install roof flashing than for the flashing itself, but it’s well worth the money to get this done professionally and get the protection your home needs. You’ll end up paying a lot more if water causes damage to your home. Getting chimney flashing is much cheaper than replacing a lot of drywall.

When you know what chimney flashing does and how it’s supposed to look, you can maintain your flashing and take care of any problems that arise as soon as you notice them. Keep your flashing in good shape and you can keep preventing leaks in your home. All in all, it’s not a huge price to pay for having a fireplace. You still get all the perks of the fireplace, along with the added knowledge that your chimney flashing is in good shape.