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Identifying and Fixing Chimney Discoloration This Summer

Chimney stains are more than a cosmetic problem. They are like color-coded signals indicating potential chimney issues like masonry damage, rust, and mold, to name a few. So folks residing in Wilmington Island, GA, Hilton Head, SC, and other communities should frequently inspect their chimney for signs of discoloration, especially after a storm.

Chimney Repair Aiken, SCWhite (Efflorescence)

White stains across portions of the chimney are known as efflorescence. It occurs when moisture penetrates deep within the brick layers drawing the salts to the surface. The stain seems to wash away when it rains, reappearing when the surface dries, making the discoloration more noticeable in the summer. Efflorescence can appear on the exterior or interior masonry. It is often the first sign that the masonry is absorbing water. If not corrected, the condition leads to further masonry damage like spalling bricks and water leaks.


When the smoke and fumes vent out of the chimney, you may notice black stains such as soot and creosote forming around the top of the stack, including the chimney cap and crown. Burning fresh or “green” wood instead of “seasoned” firewood will produce more smoke, soot, and creosote, increasing the likelihood of black stains covering the masonry. When you have black stains on the chimney’s exterior, it is likely considerably worse inside the chimney and flue. Since creosote is a highly flammable substance, black stains signify that it’s time to call a professional chimney sweep to clean the chimney. It also means the risk of exposure to toxic carbon monoxide fumes. So, spotting black sooty deposits also requires professional attention if you have a gas fireplace.

Reddish-Brown (Rust)

A masonry or factory-built chimney typically contains metal components like a chimney cap or chase cover and flashing that can begin to rust when damaged, leaving streaks of reddish-brown stains on the chimney’s exterior. Rust is almost always a sign that water is leaking inside the chimney, so it is imperative to replace the damaged components as soon as possible. Unresolved water leaks will cause extensive damage to a traditional masonry or factory-built metal chimney, including the masonry, chimney chase, and flue liner, for example. After watering your lawn, you may also notice rust stains on the lower portion of the chimney and its foundation. It can be due to hard water containing high metals like iron in your municipal water supply.


Algae is a living organism that resembles plant or moss growth. They grow on chimneys when there is significant moisture. Algae is not always green in color. Some types of algae are yellowish, brown, or red. So, it may be difficult to distinguish between algae, mold, rust, or other stains without the assistance of a Certified Chimney Sweep®. Also, some algae are like termites that can eat through the masonry and compromise its structural integrity.

Chimney Inspections and Maintenance Lexington, SCSummer Chimney Inspection & Cleaning

Schedule a chimney inspection as soon as possible if you see any stains on your chimney or fireplace. Our certified chimney professional will ensure your chimney & fireplace are safe when you are ready to light the first fire of the winter season. It will also help avoid more extensive repairs down the road.

Advanced Chimney Sweep provides certified chimney inspections, cleaning, and repairs in the CSRA and South Carolina Midlands region, including Bluffton, SC, Hardeeville, SC, Pooler, GA, and Savannah, GA. Call (706) 833-4630 or (803) 508-3990 today to schedule an appointment or contact a certified technician online.