DIY Home Repairs: Four Steps To Sealing Up Fireplace Cracks

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The sides and back of a fireplace may become weak and crack over time due to excessive heat. If you notice a crack in your fireplace—or bits of caulking or mortar on your flooring—you need to take action. Even the smallest crack can cause serious issues and increase the likelihood of a serious fire.

If you are experienced with small home repairs, you can easily repair a small fireplace crack yourself. All it takes is some time, dedication, and knowledge.

How to Repair a Fireplace Crack

If you feel up to task of repairing a crack in your fireplace, start by getting prepared. The first thing you should do is gather up the necessary materials. For this project, you will need:

Once you have all of these materials, place them near your fireplace. Put on your safety gear (gloves, mask, and glasses) and move on to the next four steps.

1. Remove Loose Mortar

Start by removing any loose mortar or caulking on your fireplace. You can use a small metal rod to remove the loose pieces. Take your time, go over the entire fireplace, and remove any loose bits. Once all the big bits of caulking are gone, carefully use the dry paintbrush to remove any remaining particles of mortar, brick, and dust.

2. Prepare the Caulking

Once all the loose bits of caulk, brick, and mortar are removed it is time to prepare the caulking. You can use any special caulk that is labeled safe for fireplaces. This type of caulk uses a silicate-based cement, which will not melt in extreme heat.

To prepare the caulk, place the tube of caulk in the caulking gun. You may need to remove a small piece of protective plastic on one end of the firestop caulk tube. Once inserted, push the handle down to ensure it is in place.

3. Apply the Caulk

Finally, you can begin to apply the caulk to the cracks. Push evenly on the lever to apply a thin, even layer of caulk to the cracks. If the cracks are large, apply multiple layers of thin caulk until the crack is sealed. Make sure you overlap your layers if you need to apply multiple layers, as this will ensure the caulk is strong and secure. Let dry.

4. Cure

Once the caulk is dry to the touch, you need to cure it with fire. Use the wood you have to create a small fire in your fireplace. The fire should be hot, but it should not be a raging fire with tall flames; instead, create a small and controlled fire. Let the fire burn for about four hours.

After four hours have passed, add more wood to increase the temperature and intensity of the fire—it should now be a large fire with tall flames. Continue to burn to the larger fire for another four hours. When the entire eight hours of curing are done, the fireplace is now ready for regular use.

There you have it: a simple guide for sealing up cracks in a fireplace. If this job sounds too difficult—or too time-consuming—for you, do not fear. Just call a fireplace or concrete professional such as Walser Contracting Ltd demolition and they can seal and cure any cracks in your fireplace for you