Englander NC30 Hearth build.

OK so the stove showed up last week.

I am contemplating building my hearth.

I have a few thoughts.

First is steel 2x4s with two layers of durarock over it then the concrete pavers we have chosen to use. That will be heavy. Anybody know the side load that you can put on steel 2x4s and the spacing for them? Also durarock is not a weight bearing material so how close should I place my steel support to hold the nc30(450 pounds) and the weight of the 1 3/4" thick concrete pavers.?

The other thought is to stack up say 2.5" of durarock to get the 1.5R value I need and put the pavers directly on that.

I called USG and they said they dont have a product for my application. And they dont reccomend durarock to be used cause it can't hold weight like that and needs to be on a solid sub floor. And that they dont Reccomend screwing multiple layers together , I guess cause maybe it could crush? Also said its cured at 200F and it could deteriorate under the concrete in the heat. I personally think this is just legal deny warranty claim stuff?

Thoughts?

 

Hmmm...this is a woodstock manual calling for an R-value of .41...Not sure if it's "apples to apples", since you're looking for 1.5, and I have not ordered the stove or built a hearth (yet), so I can not personally recomend. Maybe gives something to think about. The common r-value table is nice.

 

I can find the R value of material thats not my question. Its more about support of the materials I am referring to.

I have the stove already and it calls for 1.5R value due to how low it sits.

 

I built my hearth almost 5 years ago with 2xs (wood) then a layer of Ply. Over that I put 5 layers of 1/2" Wonderboard in perpendicular layers. No thinset, but I screwed each layer to the previous.
Thinset, then my tile.
I just loaded the stove, and plan to go to bed soon, so I can't get an accurate reading tonight, but I can shoot an IR temp. of the tile under the stove for you soon.
The underside of the ashpan is hot, and is about 5.5" from the floor. Floor to the bottom of the stove is about 8" with the included legs installed.
I don't remember the dimensions with the pedestal. I put the legs on right after the stove came in the house.
HTH

 

Thanks.

I was wondering about the wonder board?

I have never felt the stuff. Will it not crush or deflect under the weight?

 

Pics of my hearth for my 30-NC. From the literature I have, the Durock Next Gen has an R = 0.39, hence four boards thick is required to meet the 30-NC R = 1.5 requirement. I have 3/8" slate on top of my Durock but I did not use it nor consider it for the R rating value.

I designed my hearth so that there would little if any shear or bending loads on either the Durock or slate. The pics show the story. As far as stacking four boards on top of one another - why not?

Pics:










And now the Money Shot:



Good luck!

 

I dont see a problem with stacking?

The tech guy from the parent company of durrorock said not to.

 

What is the spacing of your boards for the platform.

 

What's the reason for not putting plywood down first?

 

Beautiful setup!

 

Almost exactly the same as Durock. It's a cement board.
I used a 3/4" plywood layer under to provide rigidity.
Not a single issue with anything being crushed. I would not rely merely on just the cement board, unless there were at least a couple layers perpendicular to one another with staggered seams. Seemed easy enough to add the ply in my case.
I built the whole shebang on a slab. Each stove leg has a 2x directly under it (through all the other board), and the "point load" is distributed over a 2x2' square area.
I forget the name of the fire rated board that has an insane r-value (that info is on "another" site, and maybe here too somewhere), but that would be an alternative to cement board, if you can find source, and wouldn't require several layers for the 1.5 R.

 

Micore.

 

Bingo! clemsonfor

FraggleRock

 

Wow that hearth turned out awesome! I love it!

 

Yep Micore. The reason for not wanting plywood is that would of been moving my combustibles up and I was trying to avoid that. But I dont think that will work with the steel.

My wife now is worried cause the USG tec said it could crush. She now envisions our floor crushing through the concrete pavers were putting over the durarock and sending the stove toppling and smoke filling the house I told her that there were many people that do this same thing and their stop hes are still as they were. Some have the legs on it where we will have the pedestal to further distribute load. Ours will distribution the length of the base and not in 4 points.

She said why not build a wood base and then a layer of 3/4 ply then a layer of durarock. I said cause thats not to code or to manufacture specs!!! Thats only .39r. We need 1.5. She said what about the pavers. I said concrete has .09r per inch thats basically nothing.

I think the compromise is building wood base ply. 2 sheets cement board or one Micore then sheet metal then another layer or micore or 2 sheets durarock. The metal is a compromise. Shes worried it will crush. I said well there is no "board" we can put in there thats not combustible. Only thing is sheet metal.