# R-value of high density urethane?

Asked by Andrew Thompson Zone 3a
Posted Feb 8, 2013 4:39 PM ET
Edited Feb 8, 2013 4:48 PM ET

1.

Andrew,
Here is a document that gives a thermal conductivity (K) value for three types of HDU board:
http://www.signfoam.com/pdf/signfoam3.pdf

The K value of the 15-lb. product is
0.351 BTU*in/ft^2*°F*h

Since R = 1/K where 1= the installed thickness of the insulation, the product appears to have an R-value of R-2.8 per inch.

You can perform the same calculations to determine the R-value of the other products.
10-lb. product is R-3.6 per inch
18-lb. product is R-2.5 per inch

Posted Feb 8, 2013 4:57 PM ET
Edited Feb 8, 2013 5:02 PM ET.

2.

You're a good digger, Martin.

I was hoping the numbers would be higher. Interestingly, the denser varieties have poorer performance. I was hoping for the opposite. I guess the additional or larger voids/air play a key role.

Do you happen to know what material(s) European window/door manufacturers use as rigid thermal breaks, the type that wood is directly glued to? I've seen photos, and it sure looks like it could be HDU.

Thanks again.

Answered by Andrew Thompson Zone 3a
Posted Feb 11, 2013 2:22 PM ET

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