# R Value Cement Board??



## johnnywarm (Jan 13, 2008)

Does anybody know the R Value on a Half inch thick piece of Cement board?? Also how thick is a standard Hearth Pad???


Thank you john


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## ATVriderINmass (Jan 13, 2008)

It's .26 for durock..


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## webbie (Jan 13, 2008)

No such thing as a "standard" hearth pads, but a lot of stoves require R=.8 to R=1
that would be 2" or so of Durock.


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## johnnywarm (Jan 13, 2008)

Thank you soooooo Much. My stove does requier R1. Are there 2" thick hearths?? I cannot aford a nice hearth for now. I would like to move my stove upstairs from the cellar. I can get the cement board cheap and move the stove now then wait till next winter. I would like to be able to just put the new hearth under the stove with out redoing the pipes because the cement board was to high or to low.

John


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## webbie (Jan 13, 2008)

4 pieces of Durock is about R=1, and about 2" thick. If you screw it down you will be able to remove or change it easily.

Some of the cheapie prefab stove boards available online or at Tractor Supply, etc are also R=1 (these are the boards with sheet metal over 1/2" of mineral fiber".


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## SlyFerret (Jan 13, 2008)

Here's a PDF file of the drawing that I turned in for my hearth pad permit.  It's for an Englander 30-NC.  The stove requires an R-Value of 1.5.  This pad gives me about a 1.8 by my calculations.  It ended up being three inches thick.

http://www.crystalnetworking.net/stuff/Hearth_Pad_Design.pdf

There is a chart of R-Values of various materials on this page in the Hearth Wiki.
https://www.hearth.com/econtent/index.php/wiki/Hearth_Design/


-SF


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## johnnywarm (Jan 13, 2008)

Thank's, this is a big help.

John


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