Masonry Inserts in Fireplaces

[Mike Lamb]

I see these masonry inserts in steel hearths often and they are usually cracked. Is this a safety concern? Are they just installed for looks and/or radiation?

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[Jim Katen]

The refractory panels protect the steel box from the extreme temperatures of the fire. A little cracking isn't a problem, but crumbling is. It looks like you can see the steel reinforcement in that one. I'd advise replacing it. They're readily available.

[John Dirks Jr]

This one was pretty bad. The two story slab on grade house had a real crappy elec resistance (only) furnace mounted in the attic and duct work in the ceiling of the first floor. No wonder they used the fireplace so much.

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[Tom Raymond]

My brother has one of those in his house that looks about like Lamb's. I advised him not to use it, but, while he was working on his slate floor he sliced a couple fire brick on the tile saw and tiled the back panel with them. You have to get pretty close to tell.

He is shopping for a replacement insert, but he will be limping along with the current unit until the right deal falls in his lap or he finishes evicting 1971 from the rest of the house.

[hausdok]

Wut Jim sed.

Wun Teem Wun Fyt!!!

[Eric B]

Mike, As for the cracks - the CSIA will go along with cracks if they don't break the panel into two distinct pieces or if they're not wide enough to insert a coin. As for the spalled /damaged surface there are no allowances for that. Last I heard replacing these panels (sold in sets) is about $400.00. It's also possible that a CSIA sweep will say that the unit is past its expected service life if it's on older unit - they're not rated for infinite use. If the firebox has to be replaced then there's the question of whether the new unit is compatible with (designed for) the old vent. It can get really costly.

Telling the client it's an easy fix could possibly result in you're later getting a dreaded phone call.

[Hearthman]

Hard to tell what's in the pics--I can't get them to enlarge.

Factory built fireplaces must use the OEM panels-period. I know of no one who has run aftermarket panels through the full UL 127 listing so therefore, they should not be used in factory built fireplaces in spite of the CSIA's improper position on this.

Masonry fireplaces must be built per your building code. Most codes allow for various alternative materials for a firebox. The question comes in, can you reduce the firebox wall thickness from 12" to 10" as allowed when using firebrick. For that, your AHJ must rely on test reports to rule.

Steelform fireboxes are generally allowed by codes when installed per the mfrs. instructions. These are unlisted firebox/ smoke chamber units that are approved as long as they are intact. There are no approved field repairs such as welding or firebox liners once they go bad. Period. Torch them out and rebuild the fireplace.

Point of clarification: The CSIA is NOT a code body, recognized testing lab or standards promulgation agency. They are a trade organization focused on the service of woodburning fireplaces and stoves-period. They have no authority and do not require any training in inspecting for membership or certification.