Layering Micore

[Lewiston]

I'll begin building our 54"x48" (xy) hearth this weekend and have a question regarding layering Micore. I'm upping the R and K value using (2) 3/4" layers so I don't have to replace this in the future - was planning on 1/2" but went with 3/4" since it was sold in 10' sheets.

My question is this:

Can I place the Micore layers directly on top of each other?

Ideally I would like the layering from top to bottom to be:

Tile or stone
1/2" Durock
3/4" Micore 300
3/4" Micore 300
1/2" MDF, plywood, etc
Torsion box pedestal

 

[begreen]

That's overkill, IMO, but you have the layer order correct. Personally I'd double up on the Durock and go with one layer of 3/4" Micore for a stiffer hearth.

 

[Lewiston]

I was going for an R-2.5 recommended in the "Hearth Design for Wood, Pellet and Coal Stoves" article. I have no problem adding another layer of Durock since the sides of the pad will be clad with tile or stone but this does raise another question:

Are any of the cement boards UL rated to be used for hearth construction?

 

[PapaDave]

Hearth reqs are different depending on the make and model stove.

 

[Lewiston]

Hearth reqs are different depending on the make and model stove.

I understand that; ours requires r-1.2. That being said, down the road if we replace the stove I do not want to replace the hearth or be limited in a stove purchase due to a low R rating. Since I have a 4x8 sheet of the stuff I might as well use it, or not. It's currently in the design phase.

 

[PapaDave]

I didn't want to assume you knew.
When I built mine, it was overkill for most stoves but..........just in case.
How tall will this be once complete? I went 12" on mine, and I think Dennis' (Backwoods Savage) is 16".
We REALLY like pics.

 

[Lewiston]

I didn't want to assume you knew.
When I built mine, it was overkill for most stoves but..........just in case.
How tall will this be once complete? I went 12" on mine, and I think Dennis' (Backwoods Savage) is 16".
We REALLY like pics.

I appreciate the info. The tile/stone choice to be determined by my wife, I'm not authorized, will determine the pad's thickness. Once we have that then we'll decide on the height of the pedestal. The less bending over the better since we're both on the tall side. I'll make sure to post pics once construction begins.

 

[PapaDave]

Above your pay grade, eh? hehehe
I'm only about 6', but can't handle the bending anymore. Pull up a chair, and we're off to the races.......uh, firestarting.

 

[fox9988]

My hearth is 9". If I had to do it over again, I would go 16", 12" min. Less bending, better seating.

 

[Lewiston]

Above your pay grade, eh? hehehe
I'm only about 6', but can't handle the bending anymore. Pull up a chair, and we're off to the races.......uh, firestarting.

My hearth is 9". If I had to do it over again, I would go 16", 12" min. Less bending, better seating.

You gentlemen have given me much to think about. This weekend I'm going to put together a mock hearth and see what it looks like. I like the idea of having it at the heights you've suggested.

 

[begreen]

Height may be a better way to achieve total bullet-proof R value. My objection was having 1.5" of soft underlayment and just 1/2" of solid base. However, if you add a layer of brick or two on top, this is a moot point.

 

[Lewiston]

Height may be a better way to achieve total bullet-proof R value. My objection was having 1.5" of soft underlayment and just 1/2" of solid base. However, if you add a layer of brick or two on top, this is a moot point.

You made a good point. The stove is heavy so best to have a solid base.