Pre-fabricated fireboxes have refractory panels that form an insulating barrier between the fire inside them and their sheet-metal exteriors. They are screwed into place and fit together so seamlessly that refractory mortar between them is scarcely necessary. At least, that is the goal when they have to be replaced due to extensive cracking.

Fireplace Insert - Asheville NC - Environmental Chimney

It is possible to repair a few minor cracks in a panel with refractory mortar, since that is what they are made of. But when there is significant cracking, it is time to replace the panel, otherwise you give fire direct access to the sheet metal. That can cause the firebox to warp — which, in turn, can warp the flue… and you have to replace a lot more than panels.

When there are serious cracks in the shield that refractory panels provide, the integrity of the firebox is compromised. That means your safety is in jeopardy, so they have to be replaced and the whole fireplace system needs inspection. The question, of course, is “what else happened?” …and the answer might be any of a number of things.

What Caused The Cracks?

The answer to that could also be a couple of things. It could all start with the settling of a log and a “stress crack”. If the fire ‘settles’ and gives way under a fresh log, the log crashes into a panel and the panel cracks. Cracking can also be caused by the hands of time, simply from the normal wear and tear these panels experience.

Regardless of what caused the damage, you need to know what happened as a result. Our recommendation is an inspection of your system (fireplace and chimney) by a CSIA certified sweep. Furthermore, if you want that seamless fit of your refractory panels, we would advise you to leave their replacement to fireplace professionals.