Englander NC30 Hearth build.

Someone else mentioned micore. Found some micore online with free shipping. Stuff is kinda pricey, but would make building w/wood an option. This is stated at an R-value of 1.04, then a couple sheets of cement board should give you what you need.

http://www.efireplacestore.com/sbi-ac02565.html#reviews

 

If you're talking to me, the joists are less than 12" on center and the cross pieces are about the same. I specified that I wanted the spacing no greater than 12" and I got it. I wasn't counting on the cross pieces, but I had some treated 2x6's left over and asked the carpenters how it could be used here and this is what I got.

The treated 2x6 platform is as solid as a rock, as-is the four Durock board layers screwed to the top of it. There is absolutely no flex at all in the Durock layers (there really wasn't any after just two layers). The back wall of my hearth also has two layers screwed to the studs all the way to the top. The bottom of the hearth mantle as at least 5 perhaps 7 layers of Durock screwed to it. There was two originally, but the stonemason added more so that the stone work would line up vs. cutting each mantle bottom piece to match the original height of the mantle.

You guys wondering about the strength of Durock, here's a link to a .pdf on the technical properties data for Durock. https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCAQFjAA&url=https://www.huttig.com/pdf/USG_DurockCementBoard.pdf&ei=j3QRVeKBFMGIsQSTnIKYCA&usg=AFQjCNGWTbfvncwHzVrMKLgW4T7RLneX9g&sig2=EmfrodvjFlgOXrdP72e89w&bvm=bv.89184060,d.cWc&cad=rja (If the link doesn't work, google "Durock cement board CB399".

On the third page, it states that the flexural strength is >750 psi and the indentation strength is >1250 psi. Of course, none of this really matters since you'll be putting some other concrete/stone cover over the Durock and it won't see any of these pressures, assuming you supported it adequately.

 

I sandwiched red bricks between 2 pieces of durock, then covered that with stone. The buildup part was cheap and it's very solid.

 

I won't do brick as I will already be doing large cement spacers and already have lots of weight up there.

 

I wonder how you might be able to incorporate air space into the mix to achieve the 1.5.

 

I am not as worried about air space now. Was gonna raise it on metal 2x4 but I think there too weak laterally to use. I am gonna stack I am sure now.

FTG, why did you use treated wood? Did you allow it to dry before installing it?

 

Was wondering the same.

 

We did a lot of remodeling of the house after we bought it. It's on a slab. Most of the wood touching the concrete was treated. Hence, I bought treated wood for it, buy once, cry once.

It sat for probably 4-6 weeks before we could get the carpenters out there; I don't know if that's dry or not, but it is what it is.

 

Ok so if it was on concrete yes it would need to be treated. That time is probably ok if out was climate controlled. It just looked wet in pictures.

 

That stuff is so pricey and you would need to stack anyway so I dont see much difference in using all durarock?

I would like to get just enough for one layer though.

 

Ok so you laid them down. I was thinking up on their side like floor joists. I like this option. I also like how you did the back wall with them on their side..again. I may borrow at least that back wall idea. And out the durarock over sheetrock then durarock over the studs so that I can get the 1" air gap on back for air flow and to get the 12" ctc.

 

Ok let's assume the treated wood was wet as installed. Is there an issue? What would come off of "wet" treated wood? Serious question, I have no idea.

It's done now, and been down for almost 5 months now. Should I be worried about the third arm that's now growing out of my left shoulder blade or the fact that I have a stuttering pro... pro... pro... pro... issue?

Please advise soo.... soo..... soo.... soo.... as quickly as possible.

Thanks!

 

The wood is not harm full to humans. Even the old kind with Arsenic was not really harm full, unless you eat like a pound of it!!!!

But its sealed in now so not much will off gas. well I guess its not more air tight than your walls and they lay those base framing boards down wet. I guess it would eventually dry as enough air exchanes through cracks? It it was too wet it you might have moisture/mold as it condenses in the closed area??

 

I used light steel studs the tall way topped with just two layers of durock and tile. Neither my hearthstone heritage or the blaze king have cracked a tile or fallen through. The tile distributes the stove load somewhat I'd guess. So the stove at 500# + 50# of wood plus at least two fat chicks warming their rumps up on the hearth, nearly half a freaking ton!