Step Flashing A Chimney

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Step Flashing A Chimney

For your chimney to function properly, it needs a lot of maintenance. The most popular are sweeping, tuck-pointing, liners, and so forth, however, people always tend to forget the importance if step flashing a chimney. Step flashing a chimney is one of the important practices that make your chimney function properly. So today, we're going to unearth the best practices of step flashing but not before we understand what this practice is.

What Is Step Flashing A Chimney?   

Flashing a chimney involves sealing the space formed where the chimney meets with your roof. Whatever material you use, the target is to completely lock water and moisture away from leaking into your house. Depending on the size, material, and installation, flashing can last well over 30 years. Step flashing is commonly done using one of the following materials. 

  • Aluminum flashing: This one fits for use on all types of roofs. Remember we are dealing with water here and aluminum won't be eaten up by rust like other metals. As a relatively cheaper option, aluminum is the most popular choice for flashing.
  • Copper flashing: Copper shall offer you the best flashing. You do not have to worry about bad or good weather, it's resistant to this. What you need to worry about when it comes to copper flashing is its costly price. Other than that copper flashing shall last long and look great on your roof.
  • Steel flashing: Steelworks well for flashing. Being anti-corrosive, it can comfortably withstand any weather conditions. Steel flashing is also tough and lasts longer.

Vinyl and PVC are cheap and easy to install. However, these are selective to the climate and can only work for warm weather areas. They cannot stand extreme weather conditions and break easily. Although cheap, they do not last as the previous options.

Step flashing a chimney specifically involves having your flashing material go under the shingles around your chimney and extend to the exterior of the chimney. Step flashing can also be known as base flashing.

So, how do you step flash a chimney?   

There are a lot of designs and materials that make chimneys. The most common and challenging to fix is the masonry chimney. Step flashing is a complex operation, therefore, apart from lack of the fear of heights, you need to get equipped with the skill. If it feels challenging, there are a number of professional services available to fix such. However, the DIY guy gets along with most fixes, this included.

Aluminum can be stubborn when it comes to step flashing a masonry chimney. This is because of its incompatibility with mortar. Luckily, there are a lot of other better options to choose from. Flashing involves base flashing and counter flashing.    

How to Install Flashing on Your Chimney 

Step flashing the bottom 

Step flashing as we said earlier involves installing your flashing material from below the shingles surrounding your chimney. Usually, we have a piece of step flashing material that goes up to 6 inches below the already installed shingles. It extends up to 12 inches above the shingles beside the base of your chimney wall. 

Step flashing the side

Base flashing involves the side of your chimney. Such flashing on the side of your chimney is known as step flashing. The material for step flashing can be over 3 inches wide and tall. Base flashing is attached to the deck by nailing them into position. 

What Degrades the Flashing of Your Chimney  

It is normal for chimney flashing to have issues after a period of use. The most common problems arise from poor installation, rust, or damage to the flashing. 

When a chimney is not well maintained through practices such as painting and repair, the flashing material including the nails shall rust. Since the chimney is given a separate base from the roof, over time, there shall be shifting of the roof and chimney. Such shifting shall cause differentiation and alter the installed flashing.

Poor installation might cause the flashing to spoil. Using aluminum with mortar and masonry chimneys shall cause incompatibility issues. Over time, the installed flashing wears out, the mortar for instance might crack significantly.

How to Troubleshoot Flashing Issues

If your roof flashing is leaking, finding the possible cause of such a leak shall save you both time and money for further degradation. The first thing you should look at is the parts. Check to confirm that all parts are intact. The top cap of flashing tends to give masons hard times connecting with the mortar. Due to this, joints sealed by mortar and other material can crack or detach from the flashing material causing a problem. 

Check to confirm that the flashing material's bottom cap goes up to 4 inches down the shingles. Check for any leakages under the roof. For chimneys with a 30-inch width and more, ensure there is a cricket, otherwise, check to confirm that the flashing material extends a good distance up the chimney.

DIY or Professional Step Flashing a Chimney

As you realize, step flashing a roof is a complex exercise. If you are confident enough with the skill, you can get it done. However, most self installations end up with errors that cause additional costs. It is therefore advisable that you gather materials and hire a professional to fix it for you. They are used to such fixes and rarely get things mixed up unlike when you do it yourself.


Roof leaks are majorly caused by issues with such joints as flashing. Inspect your roof before starting to confirm the exact problem. Step flashing chimney needs to be done using the correct materials and in the right manner. 

Poor installation of flashing on your roof is a recipe for disaster. Calling a professional roofing service provider to install the flashing on your roof shall ensure it is done perfectly. This avoids later unnecessary issues that shall cost you extra bucks to repair. Let your chimney sync with the roof using the correct flashing.