What causes chimneys to develop cracks?

What causes chimney cracks and chimney draft? The answer is important: if you don’t think your chimney will develop cracks, you won’t be watching for them. And then you won’t have a chance to do a quick fix before a small problem becomes a big one. That “big problem” can range from costly brick repair/replacement to dangerous gas leaks in your home, threatening the health of you and your family.

Here are five signs that you are at increased risk for chimney cracks:

1. Live in an area with a rapid freeze-thaw cycle and use the fireplace intermittently. This is especially true for wood burning fireplaces. The biggest culprit is humidity. What starts out as water vapor turns into tiny water droplets. These droplets settle in the chimney crevices and freeze if the temperature drops and you are not using the fireplace.

Then, since it has cooled down again, you light the fireplace and melt the water. The next day, he decides not to build a fire, and the water freezes in those cracks, opening them up like a pair of pliers. A couple of winters like that, and you’ve got a real problem.

2. You live in an area that is just plain cold. Long, cold winters also take a lot of wear out of the chimney. Once again, moisture is the problem. Water is called the “universal solvent” for a reason: it will dissolve anything given enough time. Look at the Grand Canyon.

When there is high humidity in a chimney, the solvent properties of the water act on the water, concrete, and bricks, slowing the removal one particle at a time until you have fissures and eventually cracks, especially if you don’t have a chimney. chimney lining or other chimney protection. If you are putting a fireplace to heavy use, you will speed up the deterioration process.

3. You have a high energy efficiency oven. Today’s high-efficiency furnaces save you money, but they also create much more moisture in the combustion air than yesterday’s lower-efficiency furnaces. All that moisture, again, increases wear and tear on the chimney and draft.

4. Do you have an oil or gas oven? In these cases, the problem is the acid. Acid fumes from burning gas and oil build up a residue that eats away at the chimney from the inside out. This can cause cracks in the clay coating, especially, and leave you with potentially expensive repairs.

5. Your chimney is not properly protected. Make sure your top plate and rain cap remain in good condition, to prevent moisture from entering the chimney. Rodents, tree branches, and harsh weather can damage them.

Another option to prevent moisture and acid buildup from causing such severe wear and tear on your fireplace is chimney liners. These products range from smooth wall coverings that prevent moisture and acid from sticking to the interior walls of the fireplace to simple protection devices that trap that residue.

The bottom line: Regardless of the type of fireplace you have, regular inspections can help give you peace of mind. Visually inspect exterior walls, bricks, and mortar for signs of cracks. Use your fingers to see if the mortar stays firmly in place or if it crumbles. For interior fireplace inspections, consider using an inspection mirror with a telescopic handle. Paired with a flashlight, the mirror will help you perform a visual inspection and spot any signs of cracks.

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