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Old Smokey's Fireplace & Chimney's Blog

What Causes Chimneys to Crack?

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.

Take Care of That Leaky Chimney

Take Care of that Leaky Chimney - Fort Wayne IN - Old Smokey'sAs weird as it may sound, water causes more damage to masonry chimneys than fire. Let’s think about that statement for a moment. All the brick and other materials that make up your home are protected by the roof and eave, all that is, except your chimney. The chimney bravely stands tall above your roof, constantly exposed to all the elements: rain, snow, and freeze/thaw cycles. A masonry chimney is constructed of a variety of masonry and metal materials, including brick, mortar, tile, steel and cast iron. All of these materials will suffer accelerated deterioration as a result of prolonged contact with water.


Masonry materials deteriorate quickly when exposed to the freeze/thaw cycle during which moisture that has managed to penetrate the materials periodically freezes and expands, causing undue stress. Water in your chimney can also cause rust in steel and cast iron components, which ultimately weakens or destroys them altogether. Water penetration can cause interior and exterior damage to your home and masonry chimney including: broken brickwork, deteriorated firebox assemblies, rusted damper assemblies, rotted adjacent wood and ruined wall coverings, deteriorated mortar, and cracked flue liners.

Most masonry materials are porous and will absorb large amounts of water. Common brick is like a sponge, absorbing water and wicking moisture to your chimney’s interior. Defective mortar joints or the use of improper mortar or brick can greatly increase the tendency to absorb and convey water to the interior of the masonry chimney structure. In addition, when water mixes with the creosote that is often present in a wood-burning fireplace, it will generate an extremely unpleasant odor that can fill your entire home. All of these things combined greatly compromise the overall structure of your chimney as a whole.


Several products have been developed specifically for use as waterproofing agents on masonry chimneys. These formulas are vapor permeable, which means that they allow the chimney to breathe out but not in. Thus water that had penetrated the chimney, or moisture that has originated from inside, is allowed to escape, while the waterproofing agent prevents water from entering from the outside. Paint, or any non-vapor permeable water sealer, should never be used as a waterproofing agent because it will trap moisture inside the chimney, which will actually accelerate its deterioration.

Water damage to masonry chimneys is usually a slow, subtle process. The problem is often not evident until it has become quite serious. Although available waterproofing measures may cost a pretty penny in up-front charges, they will save you the major expense of large masonry repairs or rebuilding of your entire chimney in the not too distant future, and, as such, represent a wise investment in your home. The last thing you want to do is hire someone that might not have the experience required for the job at hand and put your family or your home at risk. Contact us to learn why Old Smokey’s Fireplace & Chimney is your best choice.

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