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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.