Hearth Clearances

[mazcrumple]

I am going to start building a hearth for my wood stove installation and I have a few questions. The stove will be a VC Defiant or Defiant Encore. I havent decided yet, so am sizing the hearth for the larger of the 2 stoves.

First, the room is a concrete slab, tiled wall to wall. The stove requires 44" x 46" of floor protection. I am assuming that since the entire floor is non-combustable, I could sit the stove right on top of the tile if I wanted to. Under the stove I am going to be using 20" x 20" x 1.5" thick hearthstones. Am I correct in assuming that since the floor is non-combustable, I can make the stone area under the stove smaller than 44" x 46" ?

Second, the stove will be positioned parallel to wall, not in a corner. The manual says the stove requires 15" of clearance between the wall and the rear heat shield for an "Unprotected Surface", and 3" of clearance for a "Protected" surface. They suggest using a sheetmetal heat shield spaced off the wall with non-combustable spacers to make the wall "Protected". But theres no further info for other options. I am planning on using stone veneer over cement board on the wall behind the stove. How do I find out if this will allow me to position the stove closer to the wall than 15"? The Durock 1/2" cement board has an R value of .26, and the stone veneer has an R value of .476 at 1.387 inches thick.

Thanks

 

[jimbom]

As I understand, you are sizing for the Defiant since it is the larger. Clearances for the Encore may be greater, even though it is the smaller stove.

Perhaps the wall heat shield can be made of your materials if you build with a one inch space between the wall and your noncombustible board.

 

[Wood Heat Stoves]

You are correct that since the entire floor is non combustible, you can make the hearth any size you wish. You can use sheet metal spaced out an inch from the wall with non-combustible spacers open at the top and bottom for ventilation (follow the instructions in the manual for exact details). You can then put any non combustible material over this. You typically would use a wire mesh to attach the rock to. You can then measure your clearances back to the combustible part of the wall behind all this, which is typically the wall studs. Follow the clearances from the manual for the stove you are installing.

 

[mazcrumple]

Ok, so when they say I need 15" clearance between the rear of the stove and an "Unprotected" surface, they mean a combustable surface i.e. wall studs. I think I am understanding that right.

So what if I built a concrete block wall behind the stove (same width as the floor hearth) about 9" thick, making the final thickness about 12" once the stone veneer is attatched to the block. Would I then be able to place the stove 3" from my stone wall considering it would at that point still be 15" away from the original wall?

I would rather do it that way if possible. I dont think it would look good to have a 1" gap between the stone wall, and the drywall.

 

[jimbom]

Flammability is out of my knowledge, but it seems gypsum board is covered by paper. I found Vermont Castings tech support was very helpful when I had questions. They gave me no and no for an answer, but at least I was able to get the straight skinny.

 

[begreen]

Both ways can work. If just using cement board the stone veneer wall can have a cap stone ledge at the top that has a 1" vent built-in. This can be very attractive and unobtrusive. Done right, it will look very intentional. I've seen this done and it looks pretty sharp. Or you could do it your way with the block and also be fine, you are honoring the clearances either way and will have a safe installation.