Calculate R value?


Old 10-15-03, 01:42 PM
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Join Date: Aug 2003
Location: Seattle
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Calculate R value?

Can anyone let me know what the R value is of my existing walls?

They consist of (from the outside):

2.5" wide brick
1" air space
vapor barrier
3/4" sheeting (ship lap)
3.5" stud space (no insullation)
1" gypsum wall board

I am trying to determine if it is worth it to blow in insullation. House is in Seattle with moderate winter temps.


David J
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Old 10-15-03, 05:32 PM
Join Date: Nov 2001
Location: Taylors, SC
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I don't know what an energy use survey costs out there but evaluation of where and how much heat is lost might be valuable. Your local utility company may have some data on the effectiveness of certain types of insulation for your local.

Here are some tables and studies that may help.

Hope this helps.
Old 10-16-03, 06:29 AM
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Around R 4.5. The structure without the 1 inch air gap is 3.7, and you gain about 0.8 for the 1 inch air gap.
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