Have you noticed cracks in the masonry of your chimney? If you have, you may wonder what causes your masonry to crack as well as how it can be fixed.  At Old Smokey’s we want you to know that cracking brickwork and mortar can be a serious issue that may have a number of different causes. However, by keeping a watchful eye on your chimney and catching cracking issues early, you may be able to save your chimney from a more serious, and costly, repair.

Improper Construction

You may not see it, but your chimney system contracts and expands as it heats up and cools down. When you start a fire in your fireplace, it heats up your chimney flue, causing it to expand. If there isn’t proper clearance between the flue and the inside of the chimney wall, the expanding flue will start pressing into the brick causing it to crack.


Moisture can also cause masonry to crack. It can seep into the tiny pores in your brick and mortar where small amounts of water can settle. If it gets cold enough to freeze, the water will expand enough to weaken and even crack masonry. This is why it is important to protect your chimney from moisture with sealants and a chimney cap.


Having a good, solid foundation is important for any construction project. The same rings true for constructing a chimney system. If the footing for your chimney starts settling, it can cause your chimney to lean, which can lead to masonry cracking.


A good portion of your chimney is outside of your home. This means that it is exposed to a lot of naturally caused stress. Exposure to wind, hail, and other blowing debris gradually stresses your chimney, causing cracked masonry.

What can I do?

Depending on the location and severity of masonry cracks, a chimney mason may suggest different solutions to fix the issue. The best thing you can do to remedy a cracking chimney is to have it inspected by a Chimney Safety Institute of America (CSIA) certified chimney technician. Cracking can be a sign of a larger problem, so if you notice a crack, don’t hesitate to call us at 260-424-0009 or schedule an appointment online. At Old Smokey’s our certified masonry experts can give you proper guidance regarding your cracking masonry and fix any issues you may have.