soapstone fireplace liner is exploding
Our very competent contactor has installed a Rumford fireplace in our under construction house and, at our request, lined it with 2-inch thick soapstone slabs. After a few small test fires, a dinner plate sized-hunk flaked (exploded) off the back slab. The soapstone supplier said this had never happened before and he would send a replacement part. He suggested another test burn and another, even larger piece popped off one of the side panels. Does anyone have any advice on how to proceed? profjosh
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there are moisture issues here - as far as how to proceed, I'd have another talk to the soap stone supplier - how old is the construction? days? weeks? - - I don't know if moisture migration from the wet brickwork behind the soapstone could cause the problem - would seem that it's either that or something specific to that cut of soapstone - where was the soapstone stored? for how long? how long ago was it cut, and how was it stored before being shipped to you?
I'm curious if it's actually soapstone.
I have seen many fireboxes made out of it & haven't seen it pop like yours.
It's a moisture problem alright but The soapstone I have seen & worked with was non porous & wouldn't hold water in it even if you tried.
One suggestion is --- use a dehumidifier to suck out all remaining moisture.
I agree. It probably isn't true soapstone. Or maybe a slab of soapstone with an included vein of some hydrated mineral that's doing the exploding. OP has to confer with stone supplier. And save the evidence!Bill
included vein of some hydrated mineral
Soapstone is composed of the mineral talc: Mg*3Si*4O*10 (OH)*2, by definition, a hydrated mineral. A more likely explanation is interstitial water.
This is hearsay do take it accordingly. I was told by a local installer of several wood, pellet, and oil stove brands that flaking is a common problem with soapstone quarried in the US. He claims that he has never seen it in Finnish soapstone.
Could it be a thermal expansion problem? Does the soapstone have enough room to expand with the heat?
If the install was a wee-bit small, might explain popping two of them back-to-back.