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

[VanGeem, Martha]

I use the tables in Appendix A of ASHRAE Standard 90.1-2004. The 2007
version will be out soon and will have the same tables. If you want to
know which tables to use, let me know. 
 
Or you can hire consultants (like us) to calculate it for you.
 
Martha
 

Martha G. VanGeem, PE (Illinois), LEED Accredited Professional
Principal Engineer & Manager, Building Science and Sustainability 
Direct 847-972-3156 
Cell 847-736-4366
Fax 847-965-5416 
mvangeem at CTLGroup.com <mailto:mvangeem at CTLGroup.com> 

CTLGroup
Building Knowledge. Delivering Results.
5400 Old Orchard Road
Skokie, IL 60077-1030
www.CTLGroup.com 

 

________________________________

From: biggreen-bounces at lists.biggreen.org
[mailto:biggreen-bounces at lists.biggreen.org] On Behalf Of Lisa Goodwin
Robbins
Sent: Wednesday, January 09, 2008 10:20 AM
To: Big Green
Subject: Re: Big Green: Effective R-value of rigid insulation with
z-furring


We often recommend Pace Representatives, manufacturers' representatives
in the Boston area, for this type of information on wall assemblies.  At
their website, www.pacerepresentatives.com, you'll 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.  Don't you have a manufacturer's 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>
<mailto:kkicinski at bassettiarch.com>  
	
	 
	
	 
	
	
________________________________

	_______________________________________________________________
	This green building dialogue is provided as a public service 
	by Drew George, along with Environmental Building News 
	http://www.buildinggreen.com. For instructions see
http://www.biggreen.org/discussion.html
	_______________________________________________________________ 
--------------------------------------------------------
 
NOTICE OF CONFIDENTIALITY: This e-mail and any attachments are covered by the Electronic Communications Privacy Act, 18 U.S.C. 2510-2521 and may contain privileged, confidential, copyrighted, or other legally protected information. If you are not the intended recipient, you may not use, copy, or retransmit this e-mail. If you have received this by mistake please notify us by return e-mail, then delete. 
 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.biggreen.org/pipermail/biggreen/attachments/20080110/d36dc1d0/attachment.html