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Why Is My Chimney Discolored?

If you’re a homeowner with a chimney, you may have noticed some discoloration on your chimney. Stains can come in many different types and colors, and all mean different things. Some may require more attention and repair than others. Let’s take a look at several different types of chimney discoloration as well as what may be the cause of each.

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White Stains

A white stain on a chimney, is a clear sign of moisture on your chimney. The white stain typically takes on a fluffy, powdery substance and is called efflorescence. Efflorescence is a mineral salt that is left behind after water evaporates. If you see this on your chimney, you should get it checked out by a chimney professional as soon as possible as it may lead to structural issues down the line.

Black Stains

When you have fires, you’ll likely notice black soot and smoke rising — especially during the beginning of starting the fire. If you see black discoloration near the roof shingles near your chimney, it’s probably due to soot or creosote build up. While this is relatively regular and normal, it emphasizes the importance of annual maintenance and cleaning. Creosote is highly flammable so any build up should be addressed as soon as possible it mitigate any risk of a house fire.

Green or Brown Stains

A dark green or brown stain could be indicative of algae growth on your chimney. Algae is most typically found on masonry and wood, but at times it can even be found on metal chimney parts. The darker the color, the higher the concentration of the growth present. This is especially true if you live in a wetter environment.

Red Stains

The most typical cause of red stains near the chimney cap particularly is rust. The cause of this is due to exposure to oxygen and moisture. Like soot and algae growth, rust can be controlled by regular chimney inspections and cleanings.


As you can see, there are many different types of discoloration that may occur on your chimney. While the color can let you in on the potential cause, it’s not the only thing to look out for. This is why it’s important to call a chimney professional to more closely investigate the situation. After, they can determine the best plan of action moving forward.

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Call Twin City To Tackle Chimney Discoloration Today

Chimney discoloration can mean potentially serious water damage in the future, so make sure to call the experts at Twin City Fireplace, Masonry, and Chimney to make sure you’re on top of chimney care today. We’re a full-service, family-owned fireplace showroom with locations in Edina and Woodbury, MN. Our staff is highly experienced and knowledgeable and will make sure your chimney is in the best shape possible.

We’re licensed general contractors, gas fitters, and skilled masons to give you a seamless experience from the first call to the finished installation. Contact us today in Edina at 952-941-2685 or Woodbury at 651-204-0112.