I am currently working on a whole house renovation. The walls are insulated with
2 thin layers of foil. What kind of r – value does AL FOL have. The house was built
in 1962.
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Pretty much defines an R value of 1 (or even less).
All your getting is "still air" insulation.
Depends. Googling will get you all sorts of claims, especially from the foil-faced bubble-wrap outfits.
Uhm, if memory serves, AL has a U of close to 1; R is the inverse of U, so the R value (resistance to heat transfer) is about 0. Putting AL film/foil over an entrapped air space increases the reflectivity of the airspaces, but does nothing to the R value (still air is about R-1 per inch, IIRC).
Reminds me of the joke sign:
"Miracle Insulation
If you get good insulation,
it's a Miracle"
It has a wonderful insulative value against government and alien mind-beams.
=0)
Carpe that ol' diem ! ~LisaL
Are these just plain sheets of AL foil like you get from the grocery?
When I was a kid we lived in a house build around 1953. It was a story and halve.
In the attic you could see that the kneewalls where insulated with a foil product. IIRC it was laminited on paper. Much like gum wrappers.
It had several layers and it appears to be shipped flat and then "unfolded" to expand it.
Don't remember the details, but I am think that it had 3 or 4 or 5 layers.
Don't know if that was used in other parts of the hous or not.
Anyfoil as such is a very good heat conductor. But will get a little (very minor) improvement with the air effect on each surface.
You will get more improvement from the fact that if you have an 1" air space on one side that it acts as a radaint barrier. But I don't have any idea of what equivalent "R-Value" that might give.
And I am also under the impression (but don't have any documentation to this affect) is that radiant barriers are only affective where you have large tempature differences between the source of the heat and the inside. (IE, the sun). And that it will have miniumal affect on side wall heat transfers.