Why Does My Chimney Have White Stains?

Chimney With White StainsWhite staining, or efflorescence, is caused when excess moisture within the chimney structure seeps through the bricks and evaporates on their outer surfaces. The white discoloration is caused by naturally occurring salts that have been washed out of the bricks.

You may read that description and say, “Okay, that explains that.” But it actually only explains part of it. White stains on a chimney aren’t a huge problem in and of themselves – it’s not hard to wash them off with a strong cleanser and brush. The problem is the fact that sufficient water is getting into the bricks to cause the stains.

Water and bricks don’t mix

Water has a deteriorating effect on the porous bricks that comprise most chimneys. Bricks can absorb water from rain and melting snow. Water also can infiltrate bricks and mortar through cracks, which can be caused by a variety of events and often go unnoticed by homeowners until the damage is severe.

Here are some of the things that can lead to cracking in chimney bricks and mortar:

  • Old age
  • Shifting/settling of the house
  • Gale-force winds
  • Lightning strikes
  • Earthquakes
  • Violent hail storms

If water is getting into the masonry of your chimney for these or any other reasons, you have a situation that should be dealt with sooner rather than later.

The cycle of deterioration

Once bricks begin to deteriorate – whether or not you can see the damage – they will continue to degrade. A little damage leads to increasingly greater damage, which can result in a chimney with bricks falling away from the structure, a chimney that leans to one side or in the worst case scenario, a chimney that collapses.

Why excess water gets into chimneys

Chimneys With White SpotsAside from cracks in the structure, two very common reasons for water infiltration are a missing or damaged chimney cap and a damaged chimney crown. Both of these components sit atop the chimney and serve as blocks to prevent water from getting into the flue.

The chimney cap covers everything at the top of the chimney. It not only keeps water out but also prevents tree debris and small animals seeking shelter or nesting grounds from getting in. If a chimney cap is badly damaged, ill-fitting or not there at all, water has an easy path into the flue.

The chimney crown is the cement layer that covers the top chimney bricks and should have a sloped design with an overhang. If the crown is cracked, water can seep in and eventually cause serious damage, allowing more water to start another cycle of deterioration below the crown.

If you have white staining on your chimney

If your chimney is stained white, the first step is to schedule a certified chimney inspection so you can find out where the compromise exists, the severity of the damage and the best course to take in repairing the problem.

Repair could involve seal-coating the bricks, replacing missing bricks/mortar, partial or complete chimney rebuilding or other tasks, all with the goal of restoring structural integrity and safety to your chimney.

When you notice white stains on your chimney’s exterior, call Black Moose Chimney & Stove of Antrim, NH, to get the problem fixed. Our team is certified by the Chimney Safety Institute of America, which means the person working on your chimney has demonstrated the highest level of skill and training in the industry. Call us today at (603) 525-7905 for a job done right the first time.


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)