Building a hearth - is there an easy answer?

[Doobby]

I've been reading for days about hearths, I've seen a few installs up close and I thought that my plan was solid. At least until I started reading.

I have a Consolidated Dutchwest that was in my home when I bought it. This thing couldn't have been used but a few times. It's in exceptional condition. I've not used it at all. My plan was to move it to an apartment/mancave above my workshop. The floor is 3/4" plywood on 2x12 floor joists. The roof/ceiling is cathedral with a 12/12 pitch.

I planed to build a simple raised box, covered in cement board, with a stone or tile veneer. That is until I started reading. Maybe I'm confused for no reason. One article on this website talks about r value and adding up the value of the materials. Using this method, my plan is a no-go. After reading this, I later ran into threads in this forum where folks have built exactly what I had planned, with positive feedback from the members. I've also seen pictures posted here on the exact same thing that I planned, with positive feedback from the members. Heck, I've even seen pictures of a Jotul 602 set right on a cabin floor with only a sheet of metal between the stove and the plywod floor.

Is there any place out there that can give me a straight forward answer? Remove some of the mystery?

I know that you'll probably say "consult the manual". Done that, but they're not as clear as I would like them to be.

If it will help I can sketch out my idea and post it here.

 

[begreen]

What model CDW stove is this? Does it have the heat shield attached to the bottom of the stove? If so, it could be that the stove only requires ember protection.

 

[Poindexter]

Yup, what BeGreen said, two kinds of hearts. A type one hearth is ember protection only, anything nonflamable (like a piece of sheetmetal) will do.

A type II hearth provides an insulating layer between the stove an underlying combustibles. If you need a type II hearth the manual for the specific stove model should specify the R value required from the type II hearth.

 

[MarylandGuy]

When my Hearthstone stove is fully fired, the hearth underneath is cool to the touch. As begreen suggested, the metal shield under my stove deflects a lot of the heat from the hearth. It really does make a huge difference on my stove.

 

[papa bears stove]

I would think that if you used two layers of durock or hardy board laid on top of each other that you would likely make the R value needed but like I said, I'm not positive. You could also use metal studs as well to build your raised hearth.

 

[Doobby]

My CDW is a FA264, Model 2183. It does not have the heat shield attached, but one is available for this model. I understand the difference between ember protection and a type II hearth. I pland on using the stove as-is.

My confusion is building a suitable type II. I've seen a few versions here and they are all like my original plan: 2x base covered in plywood, a layer of concrete backer, and a layer of tile or stone. But if the manual and others are correct, this type of hearth is completely wrong.

I even saw a post on here where a fella built a woodstove into an alcove. The alcove had a wood substrate, concrete backer, and stone. It was beautiful, but by the manual, this would also be a no-go.

I guess what I'm saying is that if you go by what the experts say, nobody seems to be in compliance.

 

[Grisu]

I took a look at the manual: (broken link removed to http://www.fergusonfireplace.com/2183.pdf) (page 16)

I think it is pretty clear: You need the heat shield if the floor underneath the stove contains any combustible material. With heat shield you need some continuous ember protection without cracks through which ember may fall through. That ember protection may be 24 gauge sheet metal or 1/4" mineral board. (page 17)

Hence, get the heat shield and a type 1 board of sufficient size and you will be ok.

 

[begreen]

The only way the stove is permitted to use without the bottom heatshield is on a completely non-combustible surface like a concrete floor or in a fireplace. Buy the heat shield and you can proceed with your plan for the hearth.

 

[Poindexter]

I guess what I'm saying is that if you go by what the experts say, nobody seems to be in compliance.

Yup, the biggest problem I see with homebuilt hearths is counting the airspace between the subfloor and the top of the platform as part of the R value. If you were building a type II hearth (which you aren't) and started with a layer of plywood raised off the floor, that fresh piece of plywood up off the floor is combustible so you would have to build out to specified R value between that wood platform and the bottom of the stove.

But you are golden.

Peace out.

 

[Doobby]

Thanks to all. Sounds like I'm looking for a heat shield. As long as I use the shield, it's flame on, so to speak.

 

[Dakotas Dad]

You have to understand, the requirements vary from stove to stove and manufacturer to manufacturer.. In fact, our first stove required a +6 Rvalue..our second only required ember protection.. same company. THAT'S why people say read YOUR manual.

 

[Jackfre]

Doing the same thing. Excellent information. Thanks!

 

[FTG-05]

My CDW is a FA264, Model 2183. It does not have the heat shield attached, but one is available for this model. I understand the difference between ember protection and a type II hearth. I pland on using the stove as-is.

My confusion is building a suitable type II. I've seen a few versions here and they are all like my original plan: 2x base covered in plywood, a layer of concrete backer, and a layer of tile or stone. But if the manual and others are correct, this type of hearth is completely wrong.

I even saw a post on here where a fella built a woodstove into an alcove. The alcove had a wood substrate, concrete backer, and stone. It was beautiful, but by the manual, this would also be a no-go.

I guess what I'm saying is that if you go by what the experts say, nobody seems to be in compliance.

You're not, by any chance, referring to my stove install in an alcove? See pic below.

If so, the 30-NCH requirements for R=1.5 for the hearth floor were met by the installation of Durock NextGen concrete board with an R=0.39 (x4). I don't know why you say "nobody seems to be in compliance"? I think being in compliance with both the manufacturers and NFPA requirements are taken pretty seriously around here.

Post up the actual language of your stove, should be fairly easy to meet.

Good luck.

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