Conditioned Crawlspace Requirements?

[Bruce Ramsey]

Had the opportunity to inspect a conditioned crawl today. There was 1/2 inch bubble wrap on the exterior walls. I am used to seeing 2 inch Styrofoam on the walls. Can any one point the way to the insulation requirements for a conditioned crawl? Cant seem to find it in the IRC 2012. Buy the way this is new construction.

[Scott Patterson]

Bubble wrap, like for packing stuff?

[Bruce Ramsey]

Bubble wrap, like for packing stuff?
Yep. About 1/4-3/8 inch thick with a heavier white plastic covering. More like the bubble wrap envelopes. It appeared to be made as an insulation product. It was about 3 feet tall and ran all the way around the exterior foundation.

After some more poking around it looks like Table N1102.1.1 says the crawl space walls should be 5/13. Meaning is must be at least R-5 in cavities with a total of R-13 as a wall system if I read the note C correctly.

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[Scott Patterson]

I have not come across bubble wrap insulation... I have no clue.

[Billy Stephens]

Yep. About 1/4-3/8 inch thick with a heavier white plastic covering. More like the bubble wrap envelopes. It appeared to be made as an insulation product. It was about 3 feet tall and ran all the way around the exterior foundation.

After some more poking around it looks like Table N1102.1.1 says the crawl space walls should be 5/13. Meaning is must be at least R-5 in cavities with a total of R-13 as a wall system if I read the note C correctly.

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Check Here Ecofoil Crawl space Insulation - Encapsulate Your Crawl space (http://www.ecofoil.com/Applications/Crawl-Spaces-Insulation) scroll down for the white.

[Randy Mayo]

Bruce,

Some manufacturers, mostly from outside the US, are putting R-values on the label or brochures. These are misleading to the consumer. An "apparent" R-value can be given for a radiant barrier assembly, however the true R value of the material is typically 1 or less. The assembly is a mock-up or prototype that was tested in a lab. These assemblies are various combinations of reflective barrier material separated by one or more air spaces. Since heat flow through the air spaces in these mock-ups is different depending on the heat flow direction, up, down or sideways, there can be multiple tests performed. You can guess which data gets printed on the brochure. They typically use the mock-up with the highest "apparent" R-value for heat flow down and one for the heat flow up. The uninformed consumer thinks the "apparent" R-value listed on the package means this material can be placed anywhere and expect to get the R-value listed on the package. What these manufacturers don't print is these values are for a very specific application and they have to install the material exactly like the mock-up. You have to read the technical literature buried in their websites often referenced by tiny asterisks on the package. The deception is like the weight loss commercials, with the fine print at the bottom that states your results may be different and you must include exercise and a sensible diet.