This May Be Why There Are Cracks In Your Firebox & What Should You Do
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Why are Cracks in My Firebox?

You may ask why are cracks in my firebox, but it’s most important to know that immediate fireplace repair is needed. The firebox is the most visible part of the fireplace, being the interior opening where fires are built. Fireboxes serve the important function of protecting homes from two potentially life-threatening hazards. Below, learn further details about cracks in masonry fireboxes and pre-fab fireplaces.

firebox cracks, Fennimore WIWhat are the Functions of Fireboxes?

The material used for fireboxes must be designed to withstand extreme heat and to prevent toxic fumes from stealthily leaking into living areas of the home. These are the functions of both the special firebricks in the firebox and the chimney flue liner in masonry fireplaces. When they do their jobs, they are helping to prevent home fires because combustible materials near the fireplace are protected from the intense heat. As a result of continued exposure to such heat, a process called pyrolysis occurs. Pyrolysis lowers the temperature at which the combustible materials will ignite, resulting in a hazardous home fire. Fireboxes also protect against possible carbon monoxide (CO) exposure, which can be deadly.

Pre-fabricated fireboxes have refractory panels that often appear to be concrete. They are designed to look like firebricks in masonry fireplaces. The refractory panels in pre-fab fireboxes provide insulation from flames, high temperatures, and toxic fumes, as well.

Why are Cracks in My Firebox?

Whether you have a brick and mortar or refractory panel firebox, it will eventually begin to deteriorate. Inspecting fireboxes and monitoring their condition is easy. Look for cracks or crumbling mortar because when you see these and other signs of deterioration, firebox repair or replacement is necessary. It is dangerous to use a fireplace when the firebox is in a state of disrepair.

The following are also among the causes of cracks in fireboxes:

  • Hairline cracks in refractory panels are caused by repeated expansion and contraction that occurs when the panel heats up and cools down.
  • If fires are built that are too large for the pre-fab or masonry fireplace or if improper burning material is used, excessive heat can accelerate the deterioration of the firebox.
  • In a pre-fab fireplace, if water is thrown inside to extinguish embers and comes into contact with a hot panel, the panel can crack due to thermal shock.
  • Pre-fab fireplaces have been known to have defective panels that were either mishandled in the factory or were not properly cured. They often don’t crack until they’ve been installed and exposed to fires.

tuckpointing, Middleton WI

How Do You Repair A Cracked Firebox?

Tuckpointing is a procedure that can be used in masonry fireplaces when the mortar in the firepit is deteriorating. The old mortar is removed and new mortar is added, lending renewed structural integrity to the structure. Cracked panels are often replaced, though materials are available to repair cracks smaller than 1/16” wide.

Visit our Chimney Specialists Inc. showroom at 869 Main Street, Highland, WI 53543.

Call (608) 929-4887 or use our online contact form about cracks in the firebox, chimney inspections, masonry repair, and help with a new fireplace.

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