Insulation may not be a hot topic on the society page, but it definitely has
an impact on our pocketbooks and quality of life. We all know that poorly insulated
buildings are very expensive in terms of wasted energy. What many people don't
realize is there are many attractive architectural effects and structural benefits
that can be achieved by using the right combination of insulation and building
materials, saving additional money.
When it comes to insulating exterior walls, the immediate concern is protection
against air infiltration - heat or cooling loss - through the walls of a commercial
building. That concern is quite justified; it is estimated that up to 40 percent
of a building's heating or cooling costs result from air flow through cracks
around walls, doors, and windows; along ductwork; and other "leaky"
areas of a building.
Use of the right kind of insulation - polyurethane foam plastic - not only
protects against air infiltration, but can also minimize many other unwanted
conditions as well, including unwanted moisture, convection "looping,"
and outside noise penetration. In fact, the use of polyurethane foam plastic
insulation, in combination with concrete or cinder block, can add to a building's
stability and provide greater insulation. Applying polyurethane foam to the
exterior of a block structure also provides a wide range of design possibilities
- not only for new buildings, but retrofits as well. It is also environmentally
Two of the most popular types of polyurethane (PU) foam plastics commonly used
for insulating exterior walls are spray-applied PU foam and pour/froth (also
called "rigid") PU foam. Both may be applied in the field.
Spray PU foam adheres directly to substrates, the inside or outside walls of
the structure. Spray applications have no seams or joints, providing an effective
air barrier to eliminate heat or coolant leaks and minimize thermal bridging.
PU foams can be used on the interior of walls to fill cavities between studs
and can be sprayed directly on block walls or other surfaces. If sprayed on
outside walls, these foams not only provide a weather-protective substrate,
they also introduce many creative architectural possibilities, including texture
coats and facades.
Pour/froth PU foam is used to fill cavities in concrete or cinder block walls,
or in spaces between masonry walls. This type of foam cures in minutes and does
not shrink and settle. Used with certain wall-building systems, buildings insulated
with pour/froth PU foam also enjoy enhanced structural soundness and dependable,
As insulators, both types of PU foam achieve the highest thermal resistance
- "R" value - of any conventional insulation material. Spray foams
are monolithic and seamless, eliminating heating and cooling loss through seams
or joints. Pour/froth foam is not monolithic, but can also eliminate most leaks.
(In fact, most of the refrigerated containers in the world are insulated with
this type of foam). Both types of foam can be used to fit strange angles and
contour to whatever shape required.
PU foam spray-applied to exterior walls not only inhibits air infiltration,
but reduces the temperature differences between the outside and inside walls.
By reducing this temperature gradient, air movement and associated convection
"looping" or drafty effect from cold air sinking and hot air rising
- an effect that occurs in many well-insulated structures - is greatly slowed.
As a result, building occupants are more comfortable. Ed Sullivan is a staff
writer for Power in Torrance, CA. He has been involved with the construction
industry for over 20 years.