Frequently Asked Questions

What innovative energy saving techniques does spray polyurethane foam allow?

1. You won’t need house wrap with spray foam. The air and moisture sealing effects of the spray polyurethane foam are far superior to what house wraps can do. Don’t waste your money on house wrap if you are insulating with spray foam.

2. You can encapsulate your entire exterior house shell with spray foam. In effect, this creates conditioned space everywhere-including attics, basements, and crawl spaces. When ductwork is run through these areas, it is kept within conditioned space, substantially increasing the energy efficiency of your home. This reduces energy loss from recessed lights and drop ceilings while minimizing any chance of frozen pipes in colder climates.

3. Spray polyurethane foam will conform to any size or shape cavity. Bay windows, oval windows, angled walls, sloped ceilings, or any other unusual framing designs can be well insulated and tightly sealed the same as the uniform spaced stud walls.

CAUTION: Do not try these insulation techniques with conventional glass fiber batts or blown-in cellulose.

What’s a “thermal barrier” and when is it needed?
A thermal barrier is a covering on the surface of the spray polyurethane foam insulation which will protect it for at least 15 minutes in the event of a fire. ½-inch gypsum wall board, such as Sheetrock®, is an approved 15 minute thermal barrier of DC 315. Building codes require the installation of a thermal barrier between foam plastics (such as spray polyurethane foam) and any occupied space. Exceptions apply in some cases; review local codes and/or confer with your local building code officials.
How does polyurethane foam seal my house?
Polyurethane foam 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.

Air leakage can also introduce moisture into the wall cavity, resulting in wet insulation and mold and mildew. With the sealing effects of polyurethane foam insulation, this will not be a concern.

Won’t sealing my house lead to indoor air quality problems?
Your house does need to be ventilated. Most house design professionals will advise you to seal the house structure as tight as possible and provide the necessary ventilation through the heating and air conditioning system. 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.
Is spray polyurethane foam code approved?
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 barriers.
Is Dwyer’s foam approved by the U.S. Building Codes?
Yes. The three recognized model code groups in the United States all have sections relating to the approval of sprayed polyurethane foams which Dwyer’s use. The products are accepted nationwide.

Code Body Approval Section
International Conference of Building Officials (ICBO) publishes the Uniform Building Codes



Southern Building Code Congress International (SBCCI), also known as the Basic Building Code, publishes the Standard Building Code



Building Officials and Code Administrators International, Inc., (BOCA) publishes the National Building Code
At what point in the construction of my house should spray polyurethane foam be applied?
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 house shell with spray foam, spray foam insulation may need to be applied in some areas before the ductwork is installed.
Can I use spray polyurethane foam to insulate an existing home?
Spray polyurethane foam is used primarily to insulate new homes. This is because spray polyurethane foam must be applied to an open cavity. When spray polyurethane foam is injected into a closed wall cavity, the pressure of the expanding foam may damage the wall. Consider insulating an existing home with spray polyurethane foam when you’re replacing the exterior siding or doing other major remodeling.
How does spray polyurethane foam compare with glass fiber batts and blown-in cellulose?
1. 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.

2. Glass fiber batts have an R-value of about 3.5 (1-inch thickness). Blown-in cellulose has an R-value of about 3 to 4 (1-inch thickness). Spray applied polyurethane foam has an R-value of 6.5 (1-inch thickness). Thus, 3 inches of Dwyer’s foam would yield an R-value of 21.

3. 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.

4. Spray polyurethane foam will add strength and rigidity to your house. Glass fiber batts and blown-in cellulose will not.

Read more about R-values and spray insulation in our article The “R” Fairy Tale.

Will I save money if I insulate with polyurethane foam?
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 to 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 windows, etc.

One home owner from Colorado Springs reported the following to us:

“We live at 8,000 feet above sea level and have been through some severely cold winters. In our old house, which was 2,600 square feet and insulated with 3 ½-inch batts, our winter gas heating bill was about $130 per month. Our new house has 6,000 square feet of living area and 3 inches of spray foam in the walls. Our highest monthly winter gas bill has been $80. One of the main differences was the lack of drafts in our new home.”

Will spray polyurethane foam insulation lose R-value over time?
When first installed, spray polyurethane foam’s R-value is about 10 for a one-inch thickness. Over time, the R-value drops to about 6.5 (per inch) and stabilizes at that value. The time it takes to reach an R-value of 6.5 depends on a variety of factors, including total foam thickness. We report a six-month aged R-value. Many industry studies indicate that a one-inch thick sample of foam will stabilize after six months and maintain that approximate R-value for decades.
Can spray polyurethane foam be applied directly to electrical wiring? What about installed electrical devices like recessed lights?
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, stuff fiber glass around the fixture.
Will spray polyurethane foam deteriorate over time?
Not that we’re aware of. We’ve looked at 20-year old spray foam projects and we have not observed any signs of deterioration. We expect the polyurethane foam system to insulate and seal your home for the life of the house.
How long has spray polyurethane foam been used to insulate houses?
Spray polyurethane foam was commercially developed in the United States in the mid-1960’s. Homes have been insulated with spray foam since that time.
What smells does spray polyurethane foam produce in my home?
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.
Will spray polyurethane foam absorb or entrap moisture?
Most moisture problems in houses are due to moisture entry from air leakage. Because spray polyurethane foam provides such an excellent air barrier, this source of moisture is virtually eliminated. Other potential sources of moisture can be excluded with proper construction techniques and materials. Unusual building use (such as freezers or swimming pool buildings) may require a vapor retarder. Contact us regarding your specific situation if you have any questions.
Does spray polyurethane foam contain formaldehyde?
What equipment do I need to apply spray polyurethane foam?
Required equipment elements include a plural component proportioner pump with heaters, dual high pressure heated hoses, high pressure mixing and spray gun, and feed pumps and hoses. In addition, an air compressor and electrical generator may be needed.
Can a homeowner apply spray polyurethane foam?
It’s not very practical due to the expense of the equipment involved. Spray foam application requires complex equipment and a skilled installer. Dwyer’s has the experience necessary to do the job for you right!
Will spray polyurethane foam strengthen my house?
Yes! Two pound foams are 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 the kids are romping about.
How long does it take to install spray polyurethane foam?
The process is actual quite fast. A typical 2000 sq ft 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.

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