Why is my Chimney Rusting?

If your chimney shows unsightly signs of rusting, the chimney cap is the most likely cause. Rust can also form on chimney flashing and in metal flue liners, though it is not usually as immediately obvious. Whatever the cause of rust, it is important to address the problem. Depending on where the rust originates, you are at least facing repair costs that grow more expensive until a chimney sweep expert makes needed chimney repairs. Life-threatening hazards may also develop because of rust.

Rusted Chimney Repair Marietta, GARusted Chimney Caps

Unless it is made with stainless-steel or copper material, rust will eventually begin flowing from an aging chimney cap. The reddish streaks are proof that your chimney cap should be replaced.



The rust can contribute to the deterioration of your masonry and should be removed.

Rusted Chimney Flashing

The chimney flashing is the metal base that is designed to create a watertight seal between the roof and the chimney. Flashing is prone to rust.

If there is even a single rusted nail that allows water to seep through the roof, significant damage can be done. Annual chimney inspections are highly recommended by chimney safety experts, and inspections include careful examination of chimney flashing and any signs of rusting.

Rust in the Flue or a Rusted Aluminum Flue

Stainless-steel, which never rusts, is the recommended type of material for a replacement flue liner when needed. Rust can seep down into a chimney liner from a rusty chimney cap, and it puts virtually any type of liner at risk of accelerated deterioration. 

Some gas stoves are safe to use with an aluminum chimney flue. If an aluminum flue begins rusting, however, it should be replaced to prevent the need for costly chimney repair and for other dangers explained just below.

Chimney liners protect combustible parts of the home from exposure to dangerously high temperatures. Any amount of chimney liner damage creates a heightened risk of a hazardous house fire and exposure to toxic fumes. Considering all of the risks, rust should not be ignored on any part of a chimney, even in concealed areas.

Rust in the Firebox

Damage in the firebox creates dangers similar to those associated with a deteriorating chimney flue. Rust may affect the firebox as a result of rust from the chimney cap or an aluminum chimney liner. In addition, if moisture intrusion has resulted in a chimney leak, the chimney damper could rust and affect the firebox. Repairs should be made before the fireplace is used again.

atlanta ga chimney cap repairHow to Remove Rust from Chimneys

Do not make the mistake of power washing your chimney to remove rust stains, particularly if the bricks are old or have begun to deteriorate. A power wash would only cause further masonry damage, and the risky method has proven to be ineffective at completely removing rust stains from chimneys, anyway.

A trick of rust removal is to avoid further staining caused by the use of a strong acid that eats away at the masonry material. Brick and mortar cleaners are available that can be safely used without causing deterioration.

It is best, however, to leave such jobs as chimney rust removal to CSIA-certified chimney sweeps with training and experience. Climbing onto rooftops is a danger and an unnecessary risk for homeowners when you have trusted chimney professionals that you can call on, like those at Chimney Solutions. For help with a rusty chimney, chimney cleaning, chimney inspections, chimney repairs, and all chimney services, call the most trusted chimney sweeps in the Alpharetta, GA, area at (770) 771-5501.

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