- Q.We typically build
energy-efficient houses with 1-inch foil-faced
polyisocyanurate foam on the interior of our walls. But
more than one customer has questioned us about the
potential health effects of the foam. Their concerns
seem to stem from the outgasing of chemicals, more than
the potential for the foam to burn. Are such concerns
founded? What possible chemical hazards are present,
and is there any evidence that these chemicals outgas
at any substantial levels?
A.Alex Wilson
responds: Toxic chemicals are used in
producing polyisocyanurate foam. But after curing,
the foam is considered very stable and safe. The
primary health concern with this type of insulation
is exposure of factory workers to the isocyanurate
resin.
The outgasing that does occur from polyiso foam
is HCFC-141b, which is used as the foaming agent.
This gas, trapped in the foam cells, provides the
high R-value, but as it gradually leaks out the
R-value drops. In the atmosphere, HCFCs
(hydrofluorocarbons) contribute to the destruction
of the ozone layer and to global warming, but they
are not considered toxic to humans.
Healthy-house consultant John Bower reports
having tested pieces of polyiso foam on several
chemically sensitive individuals, with no
noticeable effects.
Alex Wilson is editor and publisher of
Environmental Building News, a bimonthly
newsletter published in Brattleboro, Vt. (for
subscription information, contact EBN, RR
1, Box 161, Brattleboro, VT 05301;
802/257-7300).