Big Green: Effective R-value of rigid insulation with z-furring

[Lisa Goodwin Robbins]

We often recommend Pace Representatives, manufacturers¹ representatives in
the Boston area, for this type of information on wall assemblies.  At their
website, www.pacerepresentatives.com, you¹ll find wall assemblies tailored
to the Massachusetts energy code, with calculated R-values and dewpoint
analyses.  They will also analyze alternative wall systems for Architects.
Don¹t you have a manufacturer¹s rep in your area who will do calculations
like this for you?

-- 
Lisa J. Goodwin Robbins, RA, CCS, LEED AP
Kalin Associates Inc.
1121 Washington Street
Newton, MA  02465
Tel:  617-964-5477
Fax:  617-964-5788
www.kalinassociates.com




On 1/8/08 1:24 PM, "Kristian Kicinski" <kkicinski at BassettiArch.com> wrote:

> Hello BigGreen:
> I am looking for information on how to calculate the effective r-value of
> rigid insulation when it is installed between metal z-furring channels.
>  
> Our wall assembly is as follows:
> 6" metal studs with R-21 fiberglass batts
> 1" vertical z-furring attached at each stud
> R-5 polyiso rigid insulation installed between z-furring
> 1/2" Exterior gypsum sheathing (dens-glass gold)
> Fluid-applied air barrier (Henry's)
> Cement board siding (Hardi)
>  
> During design we intended the rigid to be installed over the studs with no
> z-furring in order to prevent thermal bridging in the assembly, and for the
> gypsum sheathing to then be fastened through the rigid.  However, the
> contractor has already begun installing the z-channels, so now I am trying to
> determine the effect this will have on our energy performance, since the
> z-channels create a thermal bridge through all the insulation.
>  
> Thanks,
> Kristian Kicinski
>  
> Kristian Kicinski AIA
> LEED Accredited Professional
> 
> Bassetti Architects
> 71 Columbia St. #500 | Seattle, WA 98104
> P (206)340-9500 | F (206)340-9519
> 
> kkicinski at bassettiarch.com <mailto:kkicinski at bassettiarch.com>
> 
>  
> 
>  
> 
> 
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