Chimney stains come in many colors. None of them should be ignored. Here’s what you need to know.
White stains, also called efflorescence, happen when water evaporates and the salt in the water is left behind. These stains may or may not be a problem. If the water causing the staining has infiltrated the bricks and mortar of the chimney, it could be an issue. The only way to know the condition of a white-stained chimney is to have it inspected.
Black staining typically means that soot created by wood fires or gas/oil appliances is getting out of the flue and running down the sides of the chimney. This may be caused by excess soot that should be professionally removed by a chimney sweep. Another cause could be an improperly adjusted gas or oil heating appliance.
Red chimney stains are usually found on metal factory-built chimneys. The red you’re seeing is rust. The sides of the chimney could be rusting on their own, or there could be a leak in or damage to your chimney chase cover, which allows water to get inside, rust and spill down the exterior of the chimney. A leaky chase cover could signal internal chimney damage, so arrange an inspection if you spot rust stains.
True dark-green chimney stains are usually caused by algae growth. But because of the darkness, it may be hard to differentiate between algae and soot (see above). If it’s algae, the cause may be excess water contacting the bricks due to a chimney crown with no overhang. Algae also could be growing because of damaged areas within the masonry that are holding water. Algae should be cleaned off. Brick problems should be inspected and repaired.
Nothing causes actual brown stains on chimney masonry. If you see brown, likely it’s a combination of algae and soot mixed with the deep-red natural color of the bricks. No matter the cause, do not ignore the stain.
Any time you notice stains on your exterior chimney bricks, it’s a good idea to perform a visual examination yourself and then contact a certified chimney sweep. Under normal, “ideal” conditions, chimneys shouldn’t experience staining, so it’s important to evaluate not just the stain but the chimney structure behind the stain to determine if any damage exists. It is recommended by most chimney services groups and fire-safety agencies to have your chimney professionally inspected once a year. This process will be able to spot early signs of brick and mortar damage, chimney liner damage and damage to any of the chimney’s components and get the necessary repair work done quickly. It’s also smart to have your flue cleaned by a qualified chimney sweep once a year to prevent excess creosote and soot buildup. Soot can cause staining, and creosote is highly flammable and can lead to a chimney fire. A1 Chimney Specialist of Winchester, TN, provides certified chimney sweep services, professional chimney inspections and all levels of chimney component and structural repair. We’re your first choice to solve all chimney problems. Call (931) 967-3595 in the Winchester area, or (256) 285-4895 in and around Huntsville, AL.