A brick chimney looks like it should last forever, but the mortar holding it together has a harder life than the brick itself. As those joints erode, water gets in and the damage compounds season after season. For homeowners in Frankfort, understanding how masonry deteriorates — and catching it early — is what keeps a small repair from becoming a rebuild.
How chimney masonry deteriorates
The enemy of masonry is water, and our climate gives it plenty of opportunity. Rain and snowmelt soak into the mortar joints; when temperatures drop, that moisture freezes and expands, prying the mortar apart a little at a time. This freeze-thaw cycle repeats every winter, and over the years the joints crumble and recede. Once mortar starts failing, it lets in even more water, which speeds up the decline and begins to reach the brick and the structure behind it.
What tuckpointing is and why it matters
Tuckpointing is the repair that reverses this process. A professional grinds out the deteriorated mortar and packs the joints with fresh mortar, matched to the original in type and color. The result restores both the strength of the chimney and its ability to shed water. It is skilled work — the mortar has to be right and the technique sound — but done well, it can add decades to the life of the masonry and stop water intrusion at its source.
Catching masonry problems early
The key is not letting deterioration run unchecked. Crumbling joints, gaps between bricks, white staining, and flaking brick faces are all early signals worth acting on. Prompt chimney repair — tuckpointing and, where needed, brick replacement — keeps the job manageable. A yearly inspection is the reliable way to catch these signs while they are still minor, long before they threaten the stability of the chimney.
Crumbling mortar only gets worse with each freeze. Call Indigo Chimney Sweep at (815) 296-9565 or book online to have your masonry evaluated in Frankfort. We are bonded and insured.
Frequently asked questions
What is tuckpointing?
Tuckpointing is the process of removing deteriorated mortar from between bricks and replacing it with fresh mortar. It restores the structural integrity and weather resistance of the masonry and is one of the most common chimney repairs.
How do I know if my chimney needs tuckpointing?
Look for crumbling, cracked, or missing mortar between the bricks, gaps you can see daylight or a knife blade slip into, and loose or shifting bricks. White staining and spalling brick are related signs that water has been getting into the joints.
What causes chimney mortar to deteriorate?
Water and the freeze-thaw cycle are the main culprits. Moisture soaks into the mortar, freezes, expands, and breaks it down a little more each winter. Over years, the joints erode until they no longer hold water out or the structure firmly together.
Is deteriorating mortar a serious problem?
Yes. Failing joints let more water into the chimney, which accelerates the damage and can reach the flue and framing. Left long enough, it undermines the stability of the chimney itself, turning a modest repair into a rebuild.
What is spalling brick?
Spalling is when the face of the brick flakes, chips, or pops off, caused by trapped moisture freezing inside the brick. It is a sign of ongoing water damage and often accompanies mortar deterioration.
Can I tuckpoint the chimney myself?
It is demanding, height-dependent work that requires matching mortar type and color and proper technique for a lasting result. Poorly done tuckpointing can trap moisture or fail quickly, so it is usually best left to professionals.
How does waterproofing relate to masonry repair?
Once the joints are repaired, a vapor-permeable sealant helps keep new water out while letting the masonry breathe. Repair first, then waterproof — sealing over damaged mortar only locks problems in.
How often should chimney masonry be checked?
At each annual inspection. Catching mortar erosion or a few spalling bricks early keeps the repair small; ignoring it lets water do progressively more expensive damage.
Written by Jamie Reed, operations manager at Indigo Chimney Sweep.
Published September 10, 2026