Spalling Chimney Bricks: Why it Happens & How to Address It
Spalling is a common term used in the chimney services industry to describe chimney bricks that have begun to decay and fall apart. Older chimneys often show signs of spalling – as do newer chimneys when certain events have caused damage. If you have spalling brickwork in parts of your chimney, here’s what you need to know.
Why brick spalling happens
Spalling can occur for a variety of reasons, including:
Age of the chimney: Old age coupled with season after season of weather extremes can cause brick and mortar decay.
Cheap mortar: If the chimney was built with inferior mortar, bricks will be prone to cracking during freeze/thaw cycles when the weather causes them to expand.
Water damage: Moisture from rain and snow can infiltrate bricks and cause various degrees of decomposition.
Faulty chimney construction: Along with cheap mortar, a chimney that was improperly constructed also can cause bricks to spall. (This happens more often than you might think.)
House-settling: Every time your home settles, the roof is affected and the chimney also can be affected. It may take years, but chimney bricks eventually can begin to show signs of damage.
Bricks from salvage yards: Old salvaged bricks are never ideal to use when building a chimney. They’re already into old age and are much more prone to spalling.
To determine the exact cause of spalling bricks, enlist the services of a licensed, certified chimney inspector.
Worst-case scenarios of spalling chimney bricks
No damage to a chimney is good. But decaying bricks can lead to some very serious conditions including these three:
Water infiltration/leaky chimney: Compromised bricks allow water to enter the system. Once water gets in, cracks enlarge, more masonry falls away and the entire chimney system can become a safety risk.
Collapsed chimney: A chimney is stronger than a house of cards, but the physics are similar: when sections of bricks begin to crumble, the entire chimney can collapse.
Damage to the home: Depending on where and how much water the spalling bricks are letting in, building materials of the home adjacent to the chimney area can become rotted, moldy and generally unsafe.
How to tell if your chimney has a spalling or water-damage issue
Look for these signs:
- Efflorescence (white stains) on the exterior masonry
- Crumbling debris on the roof near the chimney
- Bricks that are loose to the touch
- Water in the firebox
- Damper that’s hard to open and close (could be rust)
- Walls and ceiling near the chimney that feel damp
- Offensive odors coming from the fireplace
Certified masonry repair for spalling bricks
If your chimney bricks are showing signs of decay, contact a local chimney sweep or chimney services company that carries national certification from the Chimney Safety Institute of America. Following a thorough chimney inspection, your technician can approach a spalling issue in several ways.
Waterproofing: If the damage is minor, a waterproof sealant may prevent further decay of bricks and mortar.
Tuckpointing: This process adds fresh, new mortar to areas of the chimney where masonry is missing.
Chimney rebuilding: When the damage is too extensive for tuckpointing to be an option, partial or complete chimney rebuilding may be necessary to restore safety to the structure.
Magic Mountain Chimney Sweeps of Frederick, MD, is ready to solve any brick spalling problem you may be having. We’re CSIA-certified and bring years of experience to all types of chimney repair projects. Talk with an expert today at (301) 695-6991.