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The Curious Case of Flaked Chimney Bricks

Flaked chimney bricks; we’ve seen them, particularly in older homes. They look weak, unsightly, and always feel like they are about to crumble, any moment, under the weight of the smoke puffing walls. And they even do.


But what causes brickworks to flake off in first place?

This form of deterioration, known as spalling, is usually the result of water damage.

Spalling in Bricks—All You Need to Know

Water is an unstoppable force of nature. It finds its way through even the smallest of cracks and openings.

Bricks that have missing mortar, are green or uncured, are more susceptible to this penetrative movement of water.

Water enters these unprotected bricks and forces their surface to peel or “flake off”, causing them to spall.

Besides water, thermal shock can also cause spalling to occur in bricks. For instance, take the example of a fire incident.

Fire causes rapid expansion of the bricks. And when water is sprayed on the bricks to extinguish the flames, the sudden change in temperature causes the bricks to crack, crumble and otherwise deteriorate.  


Spalled bricks have a low strength. They can compromise the stability of the structure, which can be a safety risk if the structure is a building, wall or chimney.

So how do you repair spalled chimney brickworks?

The only way to repair spalled chimney brick walls is to have the spalled bricks replaced— unfortunately, you can’t repair a spalled brick.

This replacement job should be done by a professional restoration company.

The company will carefully replace the affected bricks to ensure the bricks above and below the spalled bricks aren’t disturbed so the structural integrity of the chimney is maintained.

That said, preventing your chimney bricks from spalling is always a better strategy in both short and long run.

Below are some tips to prevent your chimney bricks from spalling:

  • Use cured bricks

  • Maintain your chimney cap and promptly fix any cracks or defects to prevent water from seeping into the brickwork below

  • Reseal open mortar joints by adding fresh mortar

  • Hire a chimney service company to have your chimney brickwork inspected once every year


Do you have flaked chimney brick walls at your Boston home?

Contact AMN Masonry today to have them repaired; we’re one of the leading brick and stone restoration company in Boston.   

Adriano Nunes