Stone slab hearth on wide plank floor

[slab]

Hi,

I'm new here and have a question that I haven't found a clear answer for after scouring the forum. I'm trying to install a wood stove (Pleasant hearth 1800) in my living room. The house is old (1860s) and the living room has wide plank floors-- no sub flooring, just joists. I would like to get a soapstone or granite slab to serve as a hearth pad with the stove sitting on top.

I am not sure how to attach the slab to the floor. Do I need a membrane like ditra to allow the slab to expand/contract with heat separately from the floor? Additionally it's an old house and the boards aren't totally level-- what should I use to level the hearth slab?

Thanks! Any ideas are appreciated.

 

[begreen]

Start with the insulation requirements for the stove first. According to the manual:
The floor protector must be a durable noncombustible material with a minimum thickness of 0.5” and an R value of “1.06”.
A slab of stone will need an insulator underneath it to meet this requirement.

 

[slab]

Good point. I could put down a 1/2 inch micore fiber board underneath which should get me an R value of 1.47.

Any recommendations as to how to attach the fiber board to the floor and to the slab?

 

[begreen]

It would be passive and just sit there. Micore is too fibrous to attach to. It would need a layer of cement board on top. That sandwich could be screwed down. Or two layers of 1/2" Durock NexGen (the lighter-weight concrete board) would get the R value close. This can be screwed down per mfg directions, then the slab can be set with a coat of latex-modified thinset on the cement board.

 

[71montess]

If the stove manual says ember protection is only needed, the correct size slab of stone on the floor is all that’s needed. No need to adhere it to floor either.

 

[EbS-P]

Are you planning a single piece of stone or tiling stones?

 

[begreen]

If the stove manual says ember protection is only needed, the correct size slab of stone on the floor is all that’s needed. No need to adhere it to floor either.

That is not the case here.

 

[Ashful]

Wouldn't gravity and a 600 lb. stove atop the slab be sufficient to hold it in place? I'd not be too anxious to put even more holes in an already old floor.

 

[begreen]

Wouldn't gravity and a 600 lb. stove atop the slab be sufficient to hold it in place? I'd not be too anxious to put even more holes in an already old floor.

Yes, but it will need an insulation layer in order to meet the hearth requirement.