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R-value of high density urethane?

Anybody know the approximate r-value/inch for high density urethane (HDU) board? This is the stuff used for sign board or other carving. I've found it in densities between 10-30lb/cf., in blocks, sheets, etc. It can be readily machined, glued and is waterproof. I used to use it for product design prototyping years ago. I don't think it is typically used for insulation which may explain why I can't find any r-data on it. I was thinking it might serve well for door cores or rigid thermal break applications.

Thanks in advance.

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

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2 Answers

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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

Answered by Martin Holladay, GBA Advisor
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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