[Greenbuilding] Subject: mounting rigid insulation above sloped framed un-vented roofs.

[Alan Abrams]

Corwyn--the stuff I'm looking at is Intello, interior air barrier and vapor
control layer.  it's roughly the heft of reinforced poly sheeting, but
feels more robust--like it would have no trouble supporting 12" of dense
pack on 24" centers with little bellying...maybe the 4.4# / sf is its
capacity to support insulation.

Manufacturer claims "a vapor permeability curve from .17 in winter to 13 in
summer."  magical indeed...

4.75 also distributes db+, which is more like a reinforced kraft paper.
they claim "...50% recycled content..." "...reinforced for dense pack..."
and a "vapor profile [that] varies from 0.8 perms in dry winter conditions
to 5.5 perms in moist summer conditions."

-aa

Unfortunately, I couldn't find what it varies ON in the technical spec.
>  Unless it works by having an internal calendar, how the permeability
> varies would be important to know before betting your house on it.
>
> Also, either I am reading the spec wrong, or it says: "Weight: 4.4lbs/sf"
>  So a row weighs over a ton.  That can't be right.
>
> Thank You Kindly,
>
> Corwyn
>
> --
> Topher Belknap
> Green Fret Consulting
> Kermit didn't know the half of it...
> http://www.greenfret.com/
> topher at greenfret.com
> (207) 882-7652
>
>
>
>
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