R-value of high density urethane?
designer-made
| Posted in Green Products and Materials on
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.
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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
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.