somebody set me straight about r values for durock

[robertjp]

Can anyone say for certain what the r value is for Durock 1/2" board ? Im getting conflicting info. My issue is I have to build a hearth with metal studs and I need an r value of 2.0+ for the stove I want. Im also trying to figure out what the r value would be for the air underneath the Durock. Anyone????? Thanks much BP

 

[begreen]

R .26 for 1/2" Durock. Craig has air listed at R 1.43 for an inch. So 2 layers of Durock and a 1" air space should get you very close. Add the tile and I think you'll be there.

https://www.hearth.com/econtent/index.php/articles/k_values_what_does_it_all_mean

 

[ATVriderINmass]

to make sure your at or over the R value you could put a layer of micore in the middle of the two layers of durock..

 

[robertjp]

Thanks but if you are using air underneath for r value isnt it supposed to be ventilated ? How do you ventilate metal studs?

 

[ansehnlich1]

everything you wanted to know about durock but were afraid to ask....

(broken link removed to http://www.usg.com/navigate.do?resource=/USG_Marketing_Content/usg.com/web_files/products/prod_details/DUROCK_Brand_Cement_Board.down.html)

 

[begreen]

This came up a while back. Craig said it's not needed. If you are concerned, put a layer of sheet metal on the studs before the durock.

https://www.hearth.com/talk/threads/19391/#209676

 

[robertjp]

OK so no ventilation is needed. Dumb question...... are metal studs also called drywall studs and they are not solid but have only 3 sides????? And do you stand them on the narrow side when screwing down? Thanks a million in advance. BP