Why is My Chimney Rusting?

The chimney is one of the most visible features of a home. While brick chimneys are durable structures built to withstand a crackling fire in the fireplace, they are not indestructible. The chimney comprises several different components, some of which are metal. These components, including the damper, smoke shelf, and flashing, are susceptible to rusting. 

Chimney Damage From Rust, - Hillsborough NHWhat is Rust

Ferric or Iron Oxide is a corrosive, inorganic compound that is more commonly referred to as rust. It is sometimes confused with ferrous oxide, an entirely different compound. In simplest terms, rust develops when water droplets mixed with oxygen and carbon dioxide (or other oxides) encounter ferrous metal materials such as iron or steel. The degree of oxidation depends on the amount of iron that is present in the metal and the level of oxides in the atmosphere. Since saltwater significantly accelerates oxidation, chimneys in coastal areas are more prone to rust. Humid climates also provide suitable conditions for rust.

Signs of Rusting

When rust develops, it discolors surfaces with a reddish-orange stain. Homeowners may often spot rust stains along the exterior of the chimney. It can occur when a metal chimney cap is rusting. There may also be reddish-orange rust stains along the bottom of the chimney due to the presence of iron and other oxides in the municipal water supply when watering the lawn. 

The problem with rust is that it is a part of corrosion, which can be very destructive to the chimney, including non-metal materials like clay flue tiles and brick and mortar. The rust will continue to damage the surface until it is repaired or replaced. For instance, the flashing is a metal strip that seals the gap where the chimney meets the roof. When the flashing corrodes and rusts, the seal weakens, allowing water to leak inside, resulting in further chimney damage.

Also, the combustion process that occurs when lighting the fireplace produces several oxides, including carbon dioxide, nitrogen oxide, and sulfur dioxide. The residue from these chemicals sticks to the walls and metal components in the chimney, and when it oxidizes, it exposes the flue to corrosion and rust.

How to Remove Rust Stains

Fortunately, there is an easy solution to removing rust stains from brick chimneys. Saver Systems offers a professional strength Brick and Mortar Cleaner that removes many different types of chimney stains, including rust, creosote, mildew, and algae. It is applied directly to the brick and mortar surface.  It can also remove rust from concrete surfaces and is safer than using muriatic acid to remove rust stains. 

Chimney Sweep in Amherst, NHPreventing Chimney Rust

The key to preventing chimney rust is minimizing exposure to moisture. Inspect and clean the chimney annually and make timely repairs to protect against moisture intrusion. Another way to avoid rust is to replace rusted or corroded exterior components that are exposed to the weather, like the chimney cap and flashing, with stainless steel components.  Also, non-ferrous metals do not rust, but they are still susceptible to corrosion. These metals include bronze and copper, and many homeowners have installed these types of chimney caps.  Instead, use stainless steel components when possible. Stainless steel contains chromium making it more durable than other types of metals and gives it its distinguished shiny appearance. It may be costlier, but it is more rust-resistant. A stainless-steel flue liner is also more durable and less expensive to maintain than a clay tile liner.

First Thing

John RantaJohn Ranta
17:01 22 Mar 24
They arrived on time, worked quickly and showed me the results. Prfessional throughout. jr
william greenwilliam green
23:21 14 Mar 24
Really helped me out can't say enough good things highly recommend!!!! The young man that came to my home was very knowledgeable and friendly great attitude all around answered all my questions and left me stress free best of all left no mess.🤙🏻🤙🏻
Michael Dell'OrtoMichael Dell'Orto
18:39 14 Mar 24
Jaime ConleyJaime Conley
17:13 14 Mar 24
Sarah GilliattSarah Gilliatt
01:46 13 Mar 24
A very thorough and careful job done! Thank you.
Larry CookLarry Cook
15:11 07 Mar 24
I wanted to give 5 stars but they are very busy which meant I had a good wait for both the inspection/cleaning, then for a quote on repairs and then for the repairs. Their prices seemed a little high to me but I have nothing to compare with as they were highly recommended by someone I trust and other companies had plenty of negatives reviews which kept me from getting additional quotes. I am happy with the work and they promptly returned to fix a mistake that had been made. Chris the inspector, Jennifer in the office, and Alex and his repair crew were all pleasant and took the time to answer all of my questions. Alex and his crew even took their shoes off (it was winter) before entering my house without even being asked! So if you are not in a rush and want to ensure you chimney is as safe as possible then I think you'll be happy with Black Moose.
Rebecca DeFuscoRebecca DeFusco
22:35 21 Feb 24
After a recent sweep of our chimney, it was discovered that our flue tiles were cracked. Black Moose techs were hard working, detail oriented and professional! Nice jobs guys! See you next year for my cleaning!
Karen CKaren C
14:52 14 Feb 24
Excellent I highly recommend Black Moose Chimney and Stove; Kelly and Liam are awesome, they did a great job. Extremely professional, arrived early, went through everything with a fine tooth comb ensuring pellet stove was thoroughly cleaned. They also were respectful of my home, conscientious and cleaned up after themselves. Made sure stove worked prior to leaving and told me to call promptly if anything came up afterward. Will definitely use them again.
Denise ClarkDenise Clark
16:32 31 Jan 24
We've had Black Moose clean our chimney for a number of years.But recently, we had an emergency situation at our home involving our chimney & oil furnace flue, which was caked full of soot from a malfunctioning furnace. They came & cleaned out both flues in no time, even going up on the roof with snow on it! They cleaned up after their work in the interior rooms where the oil furnace and the woodstove are located. Great work. Reasonable prices. Very nice people. You can't go wrong with Black Moose.
Joe GJoe G
18:30 24 Jan 24
Goods: The technicians know their business, very efficient in cleaning/inspection along with cleaning up after the 'dirty work'.Others: Communications could be more effective. Despite early coordination about scope of work (multiple flues within same chimney) the estimate provided did not reflect this and the final invoice was significantly more than the estimate provided.Quote for follow-on chimney relining was significantly more than that offered by other companies in the area (and far more than neighbors experienced for similar work accomplished by other companies)