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When you have a chimney system in your home, there are a lot of hearth industry terms that you end up getting to know pretty well, pretty quickly. There’s creosote — those troubling deposits that, left untended to, can create a fire hazard. There’s your chimney flashing, protecting your chimney where it meets the roofline. And there’s spalling masonry, a big headache that you definitely want to avoid.

What Is Spalling?

When excess moisture gets into your chimney, it can cause expensive and potentially dangerous problems.

When excess moisture gets into your chimney, it can cause expensive and potentially dangerous problems.

Essentially, spalling masonry is cracking, flaking or crumbling masonry, which, can take the form of a deteriorated and crumbled chimney crown or the faces of your chimney brick popping off like they were stuck-together Legos. When your masonry begins spalling, you’re dealing with a serious issue — chimney leaks are likely (almost certain), and if proper repairs aren’t made, damage can quickly compound.

What Causes Spalling?

Spalling masonry can be the result of a mix of factors:

Small Cracks And The Freeze/Thaw Cycle

Since your masonry is being bombarded by the elements day in and day out, it’s understandable that small cracks might develop, particularly in more vulnerable areas like the chimney crown. When those small cracks aren’t addressed, though, you often end up with much bigger problems thanks to what’s called the freeze/thaw cycle. Small amounts of moisture make their way inside your masonry through those cracks, and then as temperatures drop, that water freezes and expands. The expanding ice puts pressure on the masonry, causing it to crumble and flake: yep, spalling. There are a lot of reasons why we so strongly recommend being diligent about scheduling a chimney inspection every year, and this is one of them. During a chimney inspection, we’ll catch small cracks and make the necessary repairs, so you’re only having to deal with a small issue, and not a frustrating leak and major repairs.

Old And Degraded Masonry

Masonry materials are supposed to absorb a certain amount of moisture — that’s true even of brand new brick. But older masonry can start to erode and weaken — particularly in the mortar joints — allowing more moisture to wick toward the chimney’s interior. That leads to several potential problems, from chimney mold to spalling. When masonry joints recede, Ashbusters Charleston can tuck point all the damaged joints, removing crumbled mortar and replacing it with strong new watertight joints.

Improper Masonry Sealant

If there’s one surefire way to do more harm than good when trying to protect your masonry, it’s using something that isn’t vapor-permeable — like latex paint — to try and seal your chimney. Putting exterior paint on your siding can help protect it against moisture damage, but putting that same paint on your chimney? Disaster. Masonry is supposed to breathe — vapors and small particles need to be able to travel from the inside of your chimney to the outside. If they can’t, you can end up with moisture trapped in your masonry, and that can lead to spalling.

If you want to seal and protect your chimney, Ashbusters Charleston can apply a specially formulated chimney waterproofing sealant that keeps water from being absorbed, but still allows vapors to pass through like they’re supposed to.

Avoiding Spalling

There’s no exception-free way to avoid any kind of chimney damage, but there are a lot of things you can do to make headaches like spalling masonry far less likely. The key, as we see it, is to start with your annual chimney inspection. Every year, we’ll check your system top to bottom to make sure there aren’t any issues cropping up that need to be dealt with. We’ll make sure that all the components of your system designed to keep moisture out — like the chimney crown and chimney cap — are doing their job effectively. And if we find an issue or issues, we’ll make the necessary repairs.

We always recommend chimney waterproofing, too, when it comes to doing all you can to avoid spalling masonry. Waterproofing not only keeps moisture out of your system now, it helps extend the service life of your masonry, too. It’s a pretty minimal investment that we truly feel offers a big benefit.

If you have any questions about spalling or other chimney problems — or what you can do to avoid chimney problems — we’re always glad to help. Give Ashbusters Charleston a call!