A.Martin Holladay, editor
of Energy Design Update, responds: The R-value
of 3/8-inch-thick foil-faced bubble wrap is about
1.3. The R-value of 3/8-inch-thick foil-faced
expanded polystyrene foam is about 1.6.
By contrast, 2 inches of extruded polystyrene
insulation has an R-value of 10.
Bubble-wrap manufacturers who claim their
product matches the performance of 2 inches of
rigid foam are breaking the law.
In 2004 and 2005, the Federal Trade Commission
sent out a series of letters to manufacturers of
foil-faced bubble pack, warning, "The FTC staff is
aware that certain claims have been made in the
marketplace for foil-faced bubble pack products (or
similar reflective or radiant barrier products)
installed under concrete slabs. In the staff's
view, it may be misleading for industry members to
suggest that such foil products will reflect
radiant heat when installed under concrete.
"It is well accepted that reflective insulations
and radiant barrier products must have an air space
adjacent to the reflective material to be
effective. Such air spaces are unlikely to exist
under concrete slabs.
"Accordingly, it is unlikely that the reflective
qualities of these products will yield any
significant benefits when they are installed under
"In the staff's view, advertising that suggests
otherwise could harm the ability of builders and
other consumers to make appropriate insulation
Foil-faced bubble wrap is a product in search of
an application. The product has too low an R-value
to provide much benefit under a concrete slab;
moreover, the foil facing provides no benefit under
a slab beyond that of a vapor barrier.
Although some manufacturers of foil-faced bubble
pack recommend installing the product under roof
sheathing to reduce summer heat gain in an attic,
there are cheaper, foil-only products that serve
that purpose just as well.
In other applications — crawlspaces,
above-grade walls, and attic floors — the
R-value of conventional insulation (for example,
rigid foam, fiberglass batts, and cellulose) per
dollar invested will be considerably higher than
that of foil-faced bubble pack.