Why You Should Always Repair a Crack in a Fireplace

Laura Hennigan
Written by Laura Hennigan
Updated November 4, 2021
Family sitting by the fire
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Continue enjoying crackling fires safely by repairing any cracks right away

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Even though you may only use it a few months each year, you always need to keep an eye out for and repair any cracks in a fireplace.While brick and stone are known for their lasting durability, even the toughest materials can be susceptible to damage over time, and chimneys are no exception. Age, precipitation, and movement can all contribute to causing cracks or gaps inside your fireplace.With regular maintenance and timely repairs when needed, you can continue enjoying the benefits of your fireplace while staying safe and warm.

4 Causes of Cracks in a Fireplace

1. Aging

As your home and fireplace age, they may also start to erode, which can cause smaller cracks in the mortar joints. This is due to the effects of years of heating up and cooling down and the dirt under the structure continuing to settle over time.

2. Maintenance Issues

The bricks, stones, and grout in a fireplace all need regular inspection. Some areas may need resealing or reinforcement periodically to prevent cracks. If a professional didn’t build the chimney well, it might be more susceptible to damage as time goes on.

3. Precipitation

Rain, snow, and ice can make their way into even the smallest cracks of a chimney, leading to leaks. If this happens, the continued freeze-thaw cycles will eventually break down the masonry and cause larger fissures in the fireplace.

4. Movement

Movement of any kind, particularly from weather events like tornadoes and earthquakes, can cause the entire chimney to shift. If the footing at the structure’s base is too weak to handle small movements, cracks can form in and around the fireplace.

Why Is It Important to Fix a Fireplace Crack Right Away?

Well-constructed chimneys have two (or more) fire-resistant layers, including double layers of brick, double-walled steel, or steel with stone wool insulation. But once a crack forms, you begin to run the risk of flames penetrating these layers and getting to the combustible materials around the firebox. If the fissure is larger, there’s also a possibility that burning embers could blow through the crack and into the wall.

Because these are serious fire hazards, you should repair any fireplace crack ASAP, no matter how small.

How to Repair a Fireplace Crack

Modern fireplace in home
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Small Fireplace Crack Repairs

For small hairline cracks, you can purchase refractory caulk specifically rated for chimney fireboxes. You’ll need to start by cleaning out the crack and surrounding area to remove any loose mortar, then fill the crack with caulk.Note that this method is only appropriate for minor repairs and never for large cracks.

Larger Fireplace Crack Repairs

A chimney professional or a certified mason should inspect any cracks, gaps, or holes larger than a hairline. The risk is too great to try and tackle these issues as a DIY project, so be sure to locate a licensed contractor in your area.

Pros can repair many fireplace cracks if you catch the issue early enough, but you may need to replace portions of your fireplace or, in some cases, the entire fireplace.

Fireplace Crack Repair Costs

Homeowners can purchase a tube of refractory caulk for around $15 to repair any small cracks or holes. This caulk works well for repairing small chips or cracks in firebrick, re-pointing mortar joints between firebricks, and bonding bricks together.

In the case of large cracks, gaps, or holes, you should consult a professional chimney contractor or mason. A professional fix has a wide range of costs, depending on the severity of the crack, but most homeowners should expect to pay $175 to $3,000 to repair a crack.

Fireplace Maintenance

Regular fireplace maintenance will help your household stay safe while you enjoy years of cozy warmth.

Clean the Interior

Be sure to clean out wood-burning fireplaces to remove buildup and stay efficient. You should regularly remove ash, soot, and leftover wood remnants. While any homeowner can perform basic tidying up, we recommend that you hire a chimney professional once per year to perform an inspection and deeper clean.

Install a Blower and Heat-Resistant Door

Having a fan or blower installed will help circulate air and heat more efficiently. And a heat-resistant door prevents sparks and embers from escaping the hearth area, as well as keeping children and pets at bay.

Utilize Smoke and Carbon Monoxide Alarms

Having both a smoke alarm and carbon monoxide detector in the same room as your fireplace will help alert you to any potential issues. Be sure to check the batteries regularly to make sure they are working properly.

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