[Strawbale] bubble foil

[Shody Ryon]

Hi,
my understanding that bubble foil is rated at R5 and
needed a an air space for the optical aspect to work.
It would seem the R5 rate would be the best case with
all variables optimized including the foil being and
remaining clean and without dust. It may be that
concrete radiant floor advocates are using the foil
bubble insulation under concrete sometimes. I do not
think it works well for this, like an R1 or R2 as
stated in this post, because there is no optical air
space, so under concrete it would be using mostly the
bubbles for insulation. Laren, who seems to be really
smart, states that it should only be used on the
underside of of something as in a ceiling, so that it
has a good chance to stay clean. I guess he has seen
it get dirty in walls, therefor it would seem floors
are the worst use, because it would get the most dust
do to gravity. If there is no gravity, it should work
well such as in outer space, as long as the bubbles
don't over inflate and pop due to reduced atmospheric
pressure.

--- dfugler at cmhc-schl.gc.ca wrote:

> Good morning,
> 
> Regarding David Gray's suggestion to add an inch of
> bubble foil on the 
> bottom of a crawl space insulation job: DON'T DO
> THIS!
> 
> There are two reasons why this is a bad idea. The
> first is that you are 
> putting a vapour barrier on the cold side of the
> insulation. Ask Kim 
> Thompson how her straw bale insulated crawl space
> floor worked when they 
> covered it with polyethylene the first time. It
> leads to rot.
> 
> The second reason is that foil bubble wrap products
> are notorious for 
> overstating their effectiveness. They have about R-1
> or R-2 of insulation 
> value, and I have seen claims up to R-14. Here is
> the proof of their 
> insulating effectiveness (under slabs, but the
> research is still 
> relevant):
> 
> http://www.cmhc-schl.gc.ca/odpub/pdf/63728.pdf
> 
> Build it right. Foil bubble wrap is the wrong
> product for this 
> application.
> 
> Don Fugler
> CMHC Policy and Research>
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