If you have ever noticed loose bricks and chipped and broken mortar on the exterior of your chimney, you have seen examples of spalling. A form of mechanical weathering, spalling occurs at the surface of masonry materials due to large stresses underneath that surface. Caused by the freeze-thaw process or salt deposits, spalling can be a serious problem for the structure of your chimney. Since it has the highest exposure to the elements, the exterior of your chimney usually suffers more from spalling. However, water leaking into your chimney can cause spalling in its interior as well. Many of our customers at Magic Broom are unaware of the specific terms used when talking about masonry chimney repair, so we would like to take this opportunity to further explain to you what exactly spalling is.
Freeze thaw weathering
One of the most common causes of spalling in a chimney structure, the freeze thaw weathering process begins with water penetration of the bricks and mortar of your chimney. When the moisture trapped inside your chimney’s bricks and mortar freezes during the cold winter months, the volume of this moisture expands to cause cracking and spalling of the masonry. After repeated rounds of the freezing and thawing water within your chimney’s masonry materials, spalling worsens and causes structural damage to the chimney. Similarly, water can be absorbed into the bricks and mortar on the exterior surface of your chimney, and high exposure to severe freezing temperatures can cause the outer layer of the bricks to flake off when the frozen water expands.
Occurring in porous masonry building materials, this type of weathering is also caused by water penetration of your chimney. Water spreads dissolved salt through the bricks and mortar in your chimney when it leaks into these materials. As this water eventually evaporates, the salt in the water crystallizes inside the bricks and mortar close to the surface. Crystallized salt will expand and begin to build up, causing spalling on the surface of the masonry materials.
Now that you know more about why and how bricks and mortar undergo spalling, we would like to tell you about repairing spalling damage and preventing it from happening again.
Crucial to saving your chimney from further weathering deterioration, replacing the damaged bricks and mortar and locating the leak sources in your chimney should be done as soon as possible. For these repairs, you want to use certified and trained masons, like our specialists at Magic Broom, to do the tuckpointing work to replace your bricks and mortar and to pinpoint the location of the leaks and seal them. Our experienced masons pride themselves on repairing spalled bricks and mortar and quickly finding the leak source.
To best protect your chimney from spalling damage, waterproofing your entire chimney with a 100% vapor-permeable formula can prevent water penetration while allowing vapors to escape the masonry materials. You may also need to repair or replace your chimney crown or cap. Our expert technicians can also inspect the flashing on the roof around your chimney to look for cracks and deterioration to see if it should be replaced with customized flashing. Magic Broom can do all of these preventive procedures to keep your chimney safe from spalling.
Notice any loose or damaged bricks and mortar on your chimney’s exterior? Contact Magic Broom today to schedule an appointment for an inspection of the spalling deterioration by our certified technicians.