After all the trouble of trying to keep the bubble wrap off the ducts the total r value would be 2 instead of 1 which may be insufficient to prevent condensation under some conditions.
Bubble insulation r value.
Most metallic bubble wraps are about an r 1.
The product provides an r 8 0 when installed with a 0 75 air gap between the duct and the insulation and r 6 0 when installed direct to the duct without a spacer.
However we see claims of up to r 14 for some bubble products.
I have heard some say that the insulation could be installed loosely to maintain the gap.
Double bubble insulation is the most effective bubble insulation with highest r value.
Bubble and prodex total are both suitable for metal buildings pole barns homes attics roofs walls crawlspaces garages and more both are considered reflective insulation products provide r value a radiant and vapor barrier protection.
If the product is simply doubled with no air space between the layers a very minimal benefit is obtained r 1 1 per layer for the reflective double bubble product.
Worth mentioning to get the equivalent r value to what the manufactures claim on the packaging the installer has to use spacers under the insulation to keep the prescribed air gap between the ducts and the foil.
Insulation ratings are measured in r values per inch of thickness.
The approximate r value of the air space would be about 1.
R 15 2 heat flow down r 8 5 horizontal heat flow.
Are two layers of polyethylene industrialized air bubbles bonded between exterior.
Bubble foil does offer some r value because of the bubbles because remember radiant barrier does not have an r value on its own.
Some of the better manufactures state in fine print when you can find it the conductive r value of their products.
If you read the fine print this rating is always achieved as part of an overall assembly which usually includes a lot of dead air spaces.
It does as you point out change the conductive properties.
All our reflective double bubble products.
An r value tells you how well a type of insulation can keep heat from leaving or entering your home.