How To Install Chimney Flashing: [7+ Steps]

  • To install new chimney flashing, you will need to order the flashing and then measure, cut, and bend the sheet metal to fit around the chimney.
  • Make sure that the flashing is installed correctly so that it can shed water properly.
  • This is an advanced DIY project, so only attempt it if you are comfortable working on a roof and have the necessary skills.
  • Installing new chimney flashing can save you hundreds of dollars.
  • Family Handyman has a great written guide if you prefer a visual- we have a video down below that shows how to get it done, as well

My friend has always been a bit of a do-it-yourselfer, so when he started seeing water spots on the ceiling near his chimney, he decided to take care of the problem himself.

He ordered some new flashing from the hardware store and got to work.

He quickly realized that this was not as easy as it looked.

The flashing was extremely difficult to cut and bend to fit around the chimney, and he had to make several trips to the hardware store to get the right tools.

Finally, after a long and frustrating day, he managed to install the flashing properly.

But it turns out he had done it wrong. The water continued to leak, and eventually it caused serious damage to the roof and ceiling.

My friend had no choice but to call in a contractor to fix his botched job. The contractor was able to fix the flashing properly, but my friend ended up paying hundreds of dollars for the mistake.

The chimney flashing is a device installed at the top of the pipe. It’s usually made up of a round disc or flat plate and has two openings, one at its center and one at the side.

Here’s how to install chimney flashing

The purpose of the flashing is to evenly distribute any water which might come inside through the flue or gas vent pipe. There are different types of chimney flashing.



Standard Surface Flashing

The standard surface flashing has eight sides, two tops, and two bottoms. Its central opening is closed by a large circular disc held in place by lines running around it.

Standard Chimney Flashing with Spear Points

The standard chimney flashing with spear points are made of metal, most often aluminum. It’s designed to cover the entire width of a chimney wall and has two tops.

Its central opening is closed by a large circular disc held in place by lines running around it. It also has four tiny spear points on its tops and two on its bottoms, making it easier for you to secure it in position once it’s up there.

Concealed Surface Flashing

This type of chimney flashing is used when the roof pitch is not steep enough to make conventional flashing practical. It has two tops, but only one bottom. Its central opening is closed by a large circular disc held in place by lines running around it.

How to Install Chimney Flashing

Step 1

Select a chimney flashing. It must be the right one for your chimney, and you’ll need to know the width and height of your chimney walls so you can measure them correctly.

Most flashing kits will include all the components required to do the job properly, and you can always ask for assistance when buying them in case you have any questions or doubts.

Step 2

Measure your chimney walls and cut the flashing to size. Any difference between the actual measurements and those provided in the flashing kit must be considered when you’re cutting.

Use metal snips or a hacksaw to make the cuts, but don’t use power tools, as they could damage the material.

Step 3

Position the chimney flashing on top of your chimney wall and secure it in place using roofing nails through its holes. Be sure to do this properly so that no water will get inside through it. The last line of defense is always the roofer’s responsibility.

Step 4

Once the flashing is properly in place, start the installation of your chimney cap or capping brick.

Step 5

Connect the chimney flue (see above) to the chimney cap or capping brick and test to ensure the entire flue is free of air pockets.

When satisfied with the result, begin reducing the diameter of your chimney flue’s opening by removing some of its metal collars.

Step 6

When the opening has shrunk to the right size, install the chimney cap or capping brick with mortar. Make sure you cover it completely and don’t forget to apply toppings.

Step 7

Wait until the mortar has thoroughly dried, then connect your new chimney flue through its top opening to the appliance you intend to use it with.

Step 8

When you’ve successfully connected your appliance to your chimney, you can finally enjoy all the benefits of having a properly installed chimney.


Chimney flashing is an essential accessory for flues. It will ensure that no water gets inside the chimney pipe and ruins its inner lining, which can lead to a problem in the future that may require more expensive repair work.

If you’re looking to install one yourself, follow the instructions above so you don’t have any problems with it. In addition, if you’re in doubt about it, always consult a professional weatherization contractor who knows what he’s doing.

They will be able to help you whether or not you’ve heard of chimney flashing before.

Eugene Duke Pic

Hi, my name’s Eugene Duke and I love sitting by my fireplace reading a book and sipping on an adult beverage. Do you have a fireplace in your house? I’ll help you figure out the best type and style of fireplace for your home.


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