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We have some salvaged slate blackboards that we would like to use as a fireshield behind a wood burning stove (Tulikivi masonry heater, actually) to reduce required clearances to our combustible wall. Each piece is a consistent thickness, averaging around 3/8″. Our first though was to attach 1/2″ cement boards to steel studs and then thinset the slate to the boards.
Couple of questions:
1. I’ve heard that the steel studs should be screwed to a combustible wall with ceramic gaskets between the studs and wall. What are these things, and are they necessary?
2. Any thughts on drilling holes in the slate and screwing them directly to the studs, instead of going the cement board/thinset route? Is it possible to consistently drill holes in the slate without breaking it? (Each sheet is around 4′ x 5′, and I’d hate to ruin them).
3. Any reason why both of these two approaches wouldn’t work?
Thanks all.
Replies
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What is the clearance to combustibles for that tulikivi? I am sure that the slate would transfer the heat directly to anything that it's attached to. Never heard of ceramic standoffs, but I would guess that they're there to limit the contact points. Slate thinsetted to cement board would have no air space and would probably be almost as hot at the back as the front. It would increase you mass and would be a way to hold more heat for later radiating. Back to that question, what's the clearance and could you do the inch conversion please?
*A typical wood stove requires 36" clearance to combustables. Most local codes recognize an exception whereby you can cut that in half by placing a noncombustable surface like you describe at least one inch away from the cmbustable wall. This is where the ceramic spacers come in. You drill through the slate and run a screw through the spacer where the stud is and suspend the non-comb wall up by tweo inches so that cool air can be drwn in at the bottom and flow out at the top. Combined with a small measure of reflected radiant heat, the cool convection keeps things safe. I don't know enough about steel studed walls and your details to comment too specifically. Now for the practical, How will you assure youself that this slate won't get broken by fireplace tools or carelessly handled wood? Maybe laminating it to a reinforced cementious backerboard and suspending both is a good idea.
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We have some salvaged slate blackboards that we would like to use as a fireshield behind a wood burning stove (Tulikivi masonry heater, actually) to reduce required clearances to our combustible wall. Each piece is a consistent thickness, averaging around 3/8". Our first though was to attach 1/2" cement boards to steel studs and then thinset the slate to the boards.
Couple of questions:
1. I've heard that the steel studs should be screwed to a combustible wall with ceramic gaskets between the studs and wall. What are these things, and are they necessary?
2. Any thughts on drilling holes in the slate and screwing them directly to the studs, instead of going the cement board/thinset route? Is it possible to consistently drill holes in the slate without breaking it? (Each sheet is around 4' x 5', and I'd hate to ruin them).
3. Any reason why both of these two approaches wouldn't work?
Thanks all.