Hearth materals

[jacsul]

Hello,
Maybe someone can help me out here, I'm building a fireplace in my home.
Because it's going in an existing alcove I plan on building a raised platform 5 1/2" higher than the existing floor,
this platform will also serve as the hearth. the manufacturer requires a k-value of 0.84 or less.
My question is does 1/2" hardi-backer and granite floor tile meet this required k-value?
If not, what would you recommend?
Thank you in advance. :question:

 

[begreen]

What's the fireplace unit you are installing? It will probably need a bit more insulative value than mentioned. The could be achieved by using metal studs instead of wood to build up the hearth and to create an airspace. Hardibacker is not certified for hearths. Durock and Wonderboard pure cement board are. Just don't use the lightweight Gen 2 stuff.

 

[jacsul]

It's a VC winter warm system. Manufacturer recommends using 24ga. sheet metal over wonder or cement board for the hearth.
The area (platform) I'm building is 50sqft, 24ga my be cost prohibitive, so I'm looking for alternatives.
Jack

 

[jacsul]

So, any idea what I can use to achieve the desired k-value??

 

[Shari]

Scroll 1/2 way down the page for a chart of r-values.

Shari

 

[jacsul]

I'm still not getting it. I've been in construction over 20 years.
Can someone give me the R-value equivalent to a K-value of 0.84.
That I can understand.
Thanks

 

[ChipTam]

Last summer, when I installed an older Jotul #3, I had the same problem of converting a K-value into an R-value. I borrowed a friend's installation guide which had the formula. I'm sorry but I no longer have his guide. You might want to check the HearthWiki here at Hearth.com. It may be there, as well.

ChipTam

 

[begreen]

Here's the thread. R=1.19 it is. This is where the discussion of conversion for standard millboard insulation value is.

https://www.hearth.com/talk/threads/22089/

 

[jacsul]

Thank you all very much.