Sprayed Polyurethane Foam Insulation:
A Little Known Alternative With Big Benefits
by Freda Parker
"Polyurethane foam is no stranger to
us," said Monolithic's President David B.South in a
recent discussion of home insulation at MDI headquarters
in Italy, Texas. "After all, it's a major component
of the Monolithic Dome building process," he continued.
"But I'm still continually surprised by how little
the construction industry and the average American homeowner
know about this wonderful product."
South believes that this information gap
is, in large part, due to years of clever advertising and
promoting by manufacturers of fiberglass insulation. "Many
people don't even know that there are other insulating products
besides fiberglass -- one of which is polyurethane foam,"
he said. "But when people understand how insulation
works, selling them on the idea of using polyurethane becomes
a lot easier."
South explained that heat always travels
from warm to cool. For example, in cold weather we heat
our homes, but that supplied heat continually struggles
to get out of the warm room and into cooler space, such
as the unheated attic, the attached garage, or the outdoors.
It escapes via any opening, regardless of size -- a window
or door, an electrical outlet or plumbing fixture, even
a small nail hole. In hot weather, the reverse happens;
outdoor heat, using the same escape route, strives to penetrate
the cooler interior of our homes.
Ideally, by insulating a structure, we prevent
or significantly diminish this heat transfer process. "But
here's one problem," South said. "Insulation is
rated with a R-value. The R-value is supposed to indicate
that material's ability to resist heat flow. Much of the
literature, including information published by the DOE (Department
of Energy) says, 'The higher the R-value, the greater the
insulating effectiveness.' What's usually not explained
is that R-values are determined in a laboratory, rather
than a real-world environment, and how insulation works
-- its effectiveness -- in reality can be very different
from how it tests in a lab."
South cited other problems that can mitigate
R-value. For instance, a structure usually loses only about
20% of its heat through a conductive, horizontal process.
In other words, 20% of the heat escapes by penetrating the
outside wall. But that same structure can lose 80 to 90%
of its heat through convection, or wind blowing through
those walls.
"Then too, heat can be very sneaky,"
South said. "It can work itself into wood or metal
and actually leave a structure by sneaking around the insulation,
through studs and joists. Sprayed polyurethane foam or SPF
Insulation combats all these heat transfer processes --
usually more effectively than other forms of insulation.
It has many big benefits."
Information on various websites maintained
by our Department of Energy as well as the SPF industry
support South's views, and some list the benefits of SPF:
- Application process creates a seamless, water-proof,
durable building envelope
- Eliminates drafts by completely filling seams, crevices
and cracks
- Reduces energy use
- Provides high R-values
- Resists water, mildew, and fungu
- Adds structural strength
- Provides stability -- does not shrink or settle
- Reduces noise
"We automatically get all those benefits when we build
Monolithic Domes," South said. "What most people,
even some builders, don't realize is that SPF can be used
with conventional, brick-and-stick construction.
"Experience has taught me that 1.8 to
2 pound density of polyurethane foam sprayed to a thickness
of 1 1/4 inch will give the home owner 99% of the insulation
that we can expect from the walls of a house. Properly applied,
the 1 1/4" replaces the structure's exterior sheathing
and plywood corner bracing. These items are not to be taken
lightly as their installation is costly.
"The best insulated brick house you can
buy is one where the brick is laid a half inch away from
the wood studs with no sheathing," South said. "You
then spray polyurethane two inches thick onto the back side
of the brick. The reason that I specify two inches rather
than the inch and a quarter is that I want a little more
grip on the brick and studs. Polyurethane sprayed in that
manner ties the brick to the studs better than any brick
ties you can nail to the studs.
"So, the wall literally becomes one
piece," South concluded. "The brick -- for the
first time, because of the polyurethane -- actually becomes
its own total weather service. Now that's a big benefit!"
Note: Author consulted the following website:
- www.monolithic.com/articles/rfairy/index.html |
