# hardi board



## evelyn davis (May 28, 2012)

can hardy board be installed over foil faced polyiso sheathing


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## Tom Struble (Dec 29, 2008)

yes,but a drainage space is recommended in cold climates where there is no interior vapor barrier


see pg 3

http://www.jameshardie.com/pdf/USTB_Increased-Thermal-Performance-with-James-Hardie-2.pdf


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## Gary in WA (Mar 11, 2009)

Foil-faced f.b. is recommended for a hot humid climate, pp. 5: http://www.buildingscience.com/documents/guides-and-manuals/gm-guide-insulating-sheathing

Your* location* makes a huge difference on foamboard thickness, rainscreen or not, faced or not, etc.....

Gary


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## Windows on Wash (Aug 30, 2011)

Rainscreen wall designs are preferable regardless of climate region in my opinion.

+1 to a foil faced FB in hot humid climates on the exterior wall.


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## Tom Struble (Dec 29, 2008)

GBR in WA said:


> Foil-faced f.b. is recommended for a hot humid climate, pp. 5: http://www.buildingscience.com/documents/guides-and-manuals/gm-guide-insulating-sheathing
> 
> Your* location* makes a huge difference on foamboard thickness, rainscreen or not, faced or not, etc.....
> 
> Gary



question was can hardie be installed over foil face polyiso,hardie says yes with the following stipulation


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## JWilliams (Sep 22, 2010)

you tell them mr struble


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## Gary in WA (Mar 11, 2009)

As Hardie defines where/how to install their product, it may be helpful to ask where a new member lives for insulation guidance or discussion, eg. no faced f.b. in a cold climate with poly sheeting already installed on the interior under drywall.......(the dreaded) two vapor barriers. Since foil-faced was posted, I presume a colder climate..... though I've been wrong before!

On a side note; A "rainscreen" system is not needed in a hot-dry or mixed-dry according to building science, page 5 (again) the lower map titled "Exposure" (blue shades) in my post #4 link. 

Under 20" annual rainfall locations wouldn't benefit enough to pay for it (in my opinion), another map to only 16": http://maps.howstuffworks.com/united-states-annual-rainfall-map.htm 

only "where it rains"; http://www.buildingscience.com/documents/reports/rr-9909-drainage-planes-and-air-spaces

Gary


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