Durock Next Gen - Hearth?

[gloves12]

A thread here on hearth 6 years ago said that durock next gen is not ok for hearths. Also discussed here in 2011, where people decided that maybe it was still ok. I'm still seeing a lot of threads where people are still using it for that. Some people even put in next gen, read the hearth.com thread, and considered re-doing the project (they ended up leaving it).

I'm building a hearth pad that needs an R value; and I bought a few sheets of next gen, but now I'm doubtful =) Is there any other options, now that we're at 2016? Has anyone with Next Gen had problems with crumbling, or with inspections? The answers from the company seem pretty clear that it shouldn't be used:

USG, 2013: "the Durock panel does not have a fire rateing by itself it has to be part of a a assembly to achieve a fire rateing durock is good up to 225 f Durock can be used in the installment of tile under the correct condtions
we do not recommend durock used in a wood stove install application i hope this helps" (page 4 here)

 

[CheapBassTurd]

Very weird as the advertisement lists it as non combustible.

CheapMark

 

[T-roy_]

I used Next Gen in my hearth.....but then again my stove requires ember protection only.

 

[edyit]

i found this link very helpful when deciding to build my hearth.

(broken link removed)

 

[gloves12]

i found this link very helpful when deciding to build my hearth.

(broken link removed)

Hmm, so they are recommending using next gen anyway, that's reassuring =)

 

[blades]

ifrc- next gen durorock has foam beads or similar infused in the matrix- hence the reason it is useless as a hearth pad , this was done to decease the weight of a sheet while somewhat maintaining the density as well as the moisture rating.

 

[gloves12]

@blades shoot, hmm. In this thread https://www.hearth.com/talk/threads/original-type-durock.69074/page-1, begreen attached a list of materials in post #17, and it looked like there was no foam; begreen concluded he thought it would still be ok. Better to play it safe though.


Do you have any suggestions of alternatives?

 

[tarzan]

I used next gen on my hearth. FWIW, I threw some scraps in a brush pile and burned it. After about ten hours the Durock was still solid. Not that that is definitive proof. Just an observation.

 

[gloves12]

@tarzan thanks, cool! I think I saw some pictures of your burn test on the earlier threads, sweet.

 

[T-roy_]

I wouldn't worry about it, after all the sweeps library has next gen listed as a common hearth material and even has a "R" value listed. If that is what is readily available to you use it and don't look back.

 

[sportbikerider78]

I'd use 1/2 durock..that is what I did on my tile job under my wood stove. Make sure you really butter up the thinset/mortar. Tile don't like splits dropped on them.

 

[gloves12]

Awesome, thanks guys. Is there anything else that would be better? I think wonder board has the same problem now too, right?

 

[begreen]

ifrc- next gen durorock has foam beads or similar infused in the matrix- hence the reason it is useless as a hearth pad , this was done to decease the weight of a sheet while somewhat maintaining the density as well as the moisture rating.

Pumice, not foam beads. There is a shower board product that has the foam beads in it, but not Durock NexGen.

 

[Suncoast Stone]

Awesome, thanks guys. Is there anything else that would be better? I think wonder board has the same problem now too, right?

can you get hardiebacker ?

 

[bholler]

the data sheet lists it as non combustible and the tests show it passed the combustibility tests to be noncombustible.

https://www.usg.com/content/dam/USG...ck-next-gen-cement-board-datasheet-en-can.pdf

 

[EatenByLimestone]

I needed a quick hearth for my cabin. I used uncoated durock next gen. It passed inspection and 3 years of light (weekend) use. *shrug*

 

[iron]

pour some concrete?

 

[bholler]

pour some concrete?

Well standard concrete is about r.1 per inch. I believe he needs r 1.5 so that would be 15" You cant just pour a 15' thick slab on a framed floor

 

[iron]

i'm not sure how r-value works in this regards, but how about a non-combustible topping course (say 2" of concrete or cement board) with 2" of closed cell foam (r-7.5/in)?

 

[Gibraltar IV]

Lots of people have used the published R-value of 1/2" nexgen (0.39) to design their hearth pads. In my case it was 4 sheets for my stove that required 1.5 R-value. I've seen no reports of any problems from anyone and it was easy for me to install.

 

[bholler]

i'm not sure how r-value works in this regards, but how about a non-combustible topping course (say 2" of concrete or cement board) with 2" of closed cell foam (r-7.5/in)?

The problem there is that foam is combustible so you would have 2" of concrete which would be r-.2 then highly combustible foam.

 

[Jags]

Just to reinforce what BG stated above...Next gen durock DOES NOT contain foam beads. The beads are a pumice product. Another common term is pearlited aggregate.

 

[gloves12]

Lots of people have used the published R-value of 1/2" nexgen (0.39) to design their hearth pads. In my case it was 4 sheets for my stove that required 1.5 R-value. I've seen no reports of any problems from anyone and it was easy for me to install.

Just to reinforce what BG stated above...Next gen durock DOES NOT contain foam beads. The beads are a pumice product. Another common term is pearlited aggregate.

Awesome, thanks! I'm going to go for it, sounds like it's a pretty accepted method, maybe the only one, short of concrete.

 

[EatenByLimestone]

Don't forget about micore.

 

[gloves12]

Don't forget about micore.

Would that be better? I could slap some of that on top if I can find it, can't hurt.

Is that penguin from the chipmunk adventure?