R value questions

[paulestuart]

Hey Everyone,
Trying to finalize my hearth plans and ran into a problem. The only dealer of Micore is about 8 hours away. They will ship it, but it has to be cut up into 2'X4' pieces to ships via UPS. I'm wondering if cutting up the board, versus having one uniform piece, affects r values. Thanks for your help. Also, can I get a reliable R value for durock. I get everywhere from .2 to .26, makes a difference. Thanks Again,
Paul

 

[Corey]

Cutting should make no substantial difference in the overall performance - assuming we not talking confetti like strips, or 1/2 inch gaps between the pieces. I nice butted joint on 2x4 sheets should make no difference in performance. As for the Durock, US Gypsum - the maker - quotes R=.26, so I would think it safe to use their number....unless USG is also quoting .2 somewhere? otherwise seems like it may be rounding error?

(broken link removed to https://www.usg.com/navigate.do?resource=/USG_Marketing_Content/usg.com/web_files/products/prod_details/DUROCK_Brand_Cement_Board.faq.html#N2015B)

 

[paulestuart]

thanks Corey,
Thats what I was thinking too, but wanted to be sure before ordering the micore. Thanks for the Durock info too.

Have a good one,
Paul

 

[firefighterjake]

I agree with Corey . . . a few 2 foot by 4 foot pieces of Micore butted up to each other shouldn't be an issue.

Ditto on going with the .26 r value on the 1/2 Durock . . . go with the manufactuer . . . and make sure you get the original Durock.