Chimney Stains and What They Mean

Nobody likes stains. Whether on our clothing or our homes, an unexpected stain means something happened that shouldn’t have. Just like any other substance, stain color is indicative of what caused it to appear in the first place. For your home, there are four primary types of chimney stains. Here’s what they mean and how to fix them.

White stains on your chimney

White stains are most commonly caused by evaporating rainwater. This process is known as efflorescence, which simply means that the evaporation left behind various types of mineral deposits such as salt. As with green or blue stains, this usually points to some kind of crack in your chimney system.

Red or rust-like stains

Any stain with a red or brown tone is usually caused by rust. Rust forms on the metal components of your chimney such as the cap and chase. Then, when water runs down the side of your chimney mixing with the rust, it creates a reddish stain on whatever it touches. Replacing the rusty components is the best way to prevent this type of chimney stain from happening. Your Chimney Specialist, Inc technician can easily install a new cap, chase, and flashing so that type of stain doesn’t keep happening.

Green or blue stains

Chimney stains that have a green or blueish tint to them almost always point to algae or mold growth. This is sometimes true of black stains as well, though we’ll cover those shortly. Usually, this is caused by cracks or deterioration of the chimney structure, leading to water leaks. Moisture that can’t dry out or evaporate almost always leads to algae or mold. Repairing cracks in your mortar via repointing or tuckpointing is the best way to prevent this type of stain.

Black chimney stains

As we mentioned earlier, some black stains indicate mold growth. Those, however, will still have a blue tint to them. The more likely culprit of black stains on your chimney is excessive creosote buildup within the flue. A chimney sweep to eliminate creosote deposits will help mitigate this situation. In addition, burning the right kind of seasoned, dry wood throughout the year will help keep excessive creosote from forming in the first place. And of course, a regular chimney inspection and sweep — essentially, preventative maintenance — is the best way to keep black chimney stains at bay.

Inspections can identify the root cause of chimney stains

It’s easy to see stains forming on your chimney’s brick and mortar. The best thing you can do when you see any kind of stain on your chimney is to contact us for an inspection. During an inspection, our certified chimney technicians will look for the root cause of your chimney stains, remove problematic creosote build-up, and let you know of any structural issues.

Contact any of our Chimney Specialist, Inc team members by giving us a call at (608) 929-4887 to book your inspection visit. You can also get in touch via our website.