SPF Insulation FAQ's
(Frequently Asked Questions)
1. Will I save money if I
insulate with spray polyurethane foam?
2. Why the renewed interest in this
type of insulation?
3. How does spray polyurethane foam
compare with glass fiber batts and blown-in cellulose?
4. What are spray foam's air filtration
and vapor barrier advantages?
5. What are the insulation's thermal
6. Will spray polyurethane foam absorb or entrap moisture?
7. How does SPF system seal my
8. Will spray polyurethane foam
strengthen my house?
9. How does spray foam insulation affect a house's structural integrity?
10. What smells does spray polyurethane foam produce in my home?
11. Won't sealing my house lead to indoor air quality problems?
12. At what point in the construction of my house should spray polyurethane foam
13. How is foamed-in-place insulation made?
14. Can spray polyurethane foam be applied directly to electrical wiring? What
about installed electrical devices like recessed lights?
15. Is spray polyurethane foam code approved?
16. How long does it take to install spray polyurethane foam?
Q: 1. Will I save money if I insulate with spray
A: Yes! The installed cost of spray polyurethane foam is somewhat higher than
glass fiber batts or blown-in cellulose. However, the higher initial cost is
partially offset because you can leave off the house wrap and your heating and
air conditioning equipment can be smaller.
You will save in your heating fuel and electric bills. Studies suggest that
homes insulated with spray polyurethane foam use 20%-40% less energy than homes
insulated with conventional insulation. Your savings may be greater or less
depending on your life style, appliances, house site, number and size of
Q: 2. Why the renewed interest in this type of
A: Recently, savvy homebuyers have become aware of the advantages, payback
times, and investment value of home energy efficiency measures, especially those
improving the efficiency of the building envelope. In addition, the spray foam
industry has made major advances in the chemical composition and durability of
Moreover, improvements in spray foam application technology have decreased
installation costs, bringing this type of insulation system within the reach of
the residential homeowner.
Q: 3. How does spray polyurethane foam compare with
glass fiber batts and blown-in cellulose?
A: Glass fiber batts will not stop air leakage (it might filter out some dirt
and dust). Blown-in cellulose will slow down air leakage. Spray polyurethane
foam will stop air leakage…….dead.
Glass fiber batts have an R-value of about 3.5 (1 inch thickness). Blown-in
cellulose has and R-value of about 3 to 4 (1 inch thickness). Spray applied
polyurethane foam has an R-value of 6.7 to 7 (1 inch thickness).
Glass fiber batts can sag over time; blown-in cellulose can settle over time;
both situations leave sections uninsulated and you'll feel colder because of it.
Spray polyurethane foam completely adheres to wood and sheathing and is rigid;
the result is a permanent barrier to heat loss and air entry.
Spray polyurethane foam will add strength and rigidity to your house. Class
fiber batts and blown-in cellulose will not.
Q: 4. What are spray foam's air filtration and vapor
A: It reduces air infiltration by conforming to cavity shape and sealing
around wall features. In the presence of air leakage, fiberglass batt can act
more as a filter than as an insulation. Since batt does not fully conform to all
cavity shapes in corners and walls, especially at the top and bottom plates,
cold spots may appear in these areas.
Air leakage can also occur around outlets, switches, and window and door
trim. Spray foam insulation adheres and seals tightly in the cavity and reduces
air leakages cause by irregularities in surfaces.
Spray foam resists moisture due to its closed sealablitity, and dries with
minimum insulation value loss.
Q: 5. What are the insulation's thermal advantages?
A: Spray foam insulation boasts high insulation value with the best R-value
per inch of any readily available insulation. It allows for more insulation in a
tighter space than conventional batt insulation, and performs well in
controlling hot or cold temperatures. The spray foam is good at keeping heat out
as well as in, giving homeowners a break on their air conditioning bills along
with their heating bills.
Spray foam also reduces drafts by cutting convection looping. Temperature
differences between the outside and inside walls cause warm air to rise and cold
air to sink in the studs. This action initiates a convection current flowing up
and down the walls, especially with fiber batt insulation. Spray foam insulation
applied to the interior wall reduces the temperature difference of the air
Spray foam insulates hard-to-reach areas and provides a seamless layer of
Q: 6. Will spray polyurethane foam absorb or entrap
A: Moist moisture problems in houses are due to moisture entry from air
leakages. Because spray polyurethane foam provides such and excellent air
barrier, this source of moisture is virtually eliminated. Other potential
sources of moisture can be excluded with proper construction techniques and
Q: 7. How does SPF system seal my house?
A: SPF insulation is sprayed on as a liquid which reacts and expands in
place. This expansion action also seals all of the cracks and crevasses in your
wall's exterior sheathing. The result is that air can no longer slip in. Your
house will be less drafty and more comfortable.
Q: 8. Will spray polyurethane foam strengthen my house?
A: Yes! SPF is rigid and structural. Your walls will be more resistant to
winds and you'll notice less creaking and shaking when doors are slammed or when
kids are romping around.
Q: 9. How does spray foam insulation affect a house's
A: Spray foam insulation remains rigid and does not settle or sag. This means
it adds structural strength to a house while adding very little weight.
Its solid nature provides soundproofing and insect resistance, and also seals
cracks from unwanted gas and odor penetration.
Q: 10. What smells does spray polyurethane foam produce
in my home?
A: A slight odor will be present during installation of spray polyurethane
foam insulation. This will rapidly dissipate after the spraying operation stops.
After that, the installed spray polyurethane foam will be odorless.
Q: 11. Won't sealing my house lead to indoor air quality
A: Your house does need to be ventilated. Many systems employ an "air
exchanger" which is designed to pre-condition (either warm or cool) the
incoming outside air with the outgoing exhaust air. In this manner, you can
build an extremely energy efficient exterior shell using spray polyurethane foam
while still providing controlled and energy efficient ventilation.
Q: 12. At what point in the construction of my house
should spray polyurethane foam be applied?
A: Normally spray polyurethane foam is installed at the same point in the
construction cycle as other types of insulation. That is, it should be installed
after the rough plumbing, electrical wiring, and heating and air conditioning
ducts have been installed. If you decide to seal the entire exterior shell with
spray foam, spray foam insulation may need to be applied in some areas before
the ductwork is installed.
Q: 13. How is foamed-in-place insulation made?
A: The installer fabricates the foam on-site according to the manufacturer's
instructions. The application equipment and the foam's chemical components are
brought to the home-building site, where framing, electrical, and plumbing are
complete, and exterior siding encloses the home. A controlled reaction among the
number of mixed chemicals, a blowing agent, and some other additives produces a
wet foam mass.
Using a specially designed sprayer, the installer sprays or injects the mass
unto or between wall surfaces. This mass forms into a hardened cellular plastic
material. The exposed surfaces of the rigid foam resemble a hard, tan colored
Q: 14. Can spray polyurethane foam be applied directly
to electrical wiring? What about installed electrical devices like recessed
A: Spray polyurethane foam can be applied directly to electrical wiring.
Recessed lights or other fixtures may require a certain amount of air
circulation around them for cooling purposes. In these cases, a box can be built
around the fixture with gypsum wall board; then spray foam can be sprayed
directly to the outside of the box.
Q: 15. Is spray polyurethane foam code approved?
A: Yes. Building codes provide for the use of spray polyurethane foam in the
Foam Plastic section. This section of the code also describes the use of thermal
Q: 16. How long does it take to install spray
A: Quite quickly. A typical house can be fully insulated with spray
polyurethane foam in a day or less. Large houses or houses with complex design
features could take longer.