Spray Foam Insulation FAQ

Click on a question below to reveal the answer. If you have questions not answered here, contact NCFI.
Are spray polyurethane foam (SPF) and CPVC chemically compatible?

Yes, SPF and CPVC are chemically compatible. Please contact your local NCFI Representative for specific application instruction. Also see the attached study on the right hand side under downloads for further information.

When can spray polyurethane foam insulation be installed?

Spray polyurethane foam insulation is professionally 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, but before the interior walls are completed in new construction. In some cases SPF can also be applied in older buildings or structures, to the inside of roofs, and under floors after construction has been completed.

How does spray foam work?

A two-part mixture is applied by trained professionals to the surface to be insulated. The spray mixture expands rapidly to fill all cracks and voids, completely and permanently adhering to wood, masonry, metal, concrete and most other construction materials.

Which is better, open or closed-cell spray foam insulation?

Both systems offer significant advantages over fiber-based insulations: ability to air seal; ability to fill cracks and conform to odd shaped cavities; and ability to hold their shape over time and under adverse conditions. But only closed-cell foam has the thermal insulation value (R-value) to bring your building up to Energy Star® standards with only one-half the thickness required for fiber insulations. In addition, closed-cell foam products increases the strength of your wall system (it's approximately doubled) and increase the water resistance of your building’s exterior.

How does closed-cell spray foam provide moisture protection, yet still breathe?

Unlike cellulose and fiberglass materials, closed-cell foam insulation is impervious to water penetration and wicking. Yet, like Gortex® fabric, the closed-cell structure allows the diffusion of water vapor (high energy particles) to allow your building’s envelope to “breathe”. Liquid water has much larger particles and is unable to pass into or through a closed-cell foam barrier.

What’s a "thermal barrier" and when is it needed?

A thermal barrier is a covering between the interior of a building and the surface of the spray polyurethane 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. Building codes require the installation of a thermal barrier between foam plastics (such as spray polyurethane insulation) and any occupied space. Exceptions apply in some cases; review local codes and/or confer with your local building code officials. The building code provides for an exception to the thermal barrier requirement in attics and crawl spaces where entry is made only for the service of utilities. In such cases, the spray polyurethane insulation must be protected from ignition. NCFI offers Aldocoat 757, a spray-on ignition barrier coating for these areas.

How does the NCFI spray polyurethane insulation seal my building?

NCFI spray polyurethane insulation is sprayed on as a liquid which reacts and expands in place. This expansion action aids in sealing cracks and crevasses in your wall’s exterior sheathing. Your building 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 NCFI spray polyurethane insulation, this will not be a concern.

Won’t sealing my building lead to indoor air quality problems?

Your building does need to be ventilated. Most design professionals will advise you to seal the 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 insulation code approved?

Yes. Building codes provide for the use of spray polyurethane insulation in the Foam Plastic section. This section of the code also describes the use of thermal barriers.

At what point in the construction should spray polyurethane insulation be applied?

Normally spray polyurethane insulation 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 polyurethane, spray insulation may need to be applied in some areas before the ductwork is installed.

Can I use NCFI spray polyurethane to insulate an existing building?

Spray polyurethane insulation is used primarily to insulate new buildings or structures. This is because spray polyurethane must be applied to an open cavity. When spray polyurethane is injected into a closed wall cavity, the pressure of the expanding insulation may damage the wall. Consider insulating an existing building with spray polyurethane when you’re replacing the exterior siding or doing other major remodeling.

Will I save money if I insulate with NCFI's spray polyurethane insulation?

Yes! The installed cost of spray foam insulation 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 wrap and your heating and air conditioning equipment can be smaller. You will save in your heating fuel and electric bills. Studies suggest that buildings insulated with SPF insulation use 20 to 40 percent less energy than those insulated with conventional insulation. Your savings may be greater or less depending on your structure’s appliances, building site, number and size of windows, etc.

Will spray polyurethane insulation lose R-value over time?

Open-cell spray foam insulations trap air to create the R-value and therefore stabilize very quickly after the application, resulting in R-values per inch of thickness the same as fiber based insulation, which also attempt to trap air to provide its R-value. Closed-cell systems utilize a blowing agent that creates an inert gas of complex molecules that are highly resistant to heat flow. The foam is formed by the chemical reaction of two hot liquids and this reaction also creates more heat in the process. This hot gas, in the 160ºF range, is trapped in the foam matrix during the chemical reaction as the cell walls form the micro-cellular membrane. As this gas cools back to room temperature, the cell walls remain fixed, setting up a lower air pressure inside the cell than the air in the atmosphere. While the large inert gas molecules are trapped inside the cells, the much small molecules of elements in the air can diffuse into the cells. Due to the lower pressure inside the cells, the smaller molecules diffuse into the cells over time, stabilizing the pressure, which also reduces the heat transfer resistance of the foam; or lowers the R-value. The R value stabilizes and remains at that level unless the foam is cut or damaged. This reduction is typically 2 to 4 percent, so the R-value reduction will be a couple of tenths, something like an R-value of 6.7 measured just after spraying will stabilize at 6.4 or so. The stabilized R-value is measured by an industry, building code approved ASTM protocol. All manufacturers of closed-cell foams are required to “age” the foam and measure and report the stabilized R-value using these approved ASTM test methods. When first installed, spray polyurethane foam’s R-value is about 10 for a one-inch thickness. Over time, the R-value drops to between 6.5 and 7.0 (one inch) and stabilizes at that value. The time it takes to reach an R-value of 6.5 to 7.0 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 insulation be applied directly to electrical wiring? What about installed electrical devices like recessed lights?

Spray polyurethane 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 build around the fixture with gypsum wall board; then spray foam can be sprayed directly to the outside of the box.

Will spray polyurethane insulation deteriorate over time?

Ultra-violet light (sunlight) will cause the foam to degrade over time, so polyurethanes applied to surfaces that will be subjected to sunlight (an outdoor tank) will need to be covered or coated with a UV barrier coating. For interior applications as in your house walls, we are not aware of anything that will degrade the foam. We’ve looked at 20-year old spray foam projects when remodeling required the walls be opened, and have not observed any signs of deterioration. We expect the NCFI spray polyurethane insulation system to insulate and seal your building for the life of the structure.

How long has spray polyurethane foam been used to insulate houses?

SPF was commercially developed in the United States in the mid-1960s and buildings have been insulated with spray foam since that time. NCFI is aware of houses insulated with our spray foams in the early 1970’s.  NCFI is one of the leading spray polyurethane foam insulation manufacturers in the United States.

Will spray polyurethane insulation absorb or entrap moisture?

Most moisture problems in houses are due to moisture entry from air leakage. Because spray polyurethane insulation 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 NCFI regarding your specific situation if you have any questions.

What equipment do I need to apply spray polyurethane insulation?

Required spray foam equipment elements include a plural component proportioner pump with heaters, dual high pressure heated hoses, high pressure mixing spray gun, feed pumps and hoses. In addition, an air compressor and electrical generator may be needed.

Can a building owner apply spray polyurethane insulation?

Not practically. Spray polyurethane foam application requires complex spray foam insulation equipment and a spray foam insulation contractor that is a certified, skilled applicator.

Will spray polyurethane insulation strengthen my structure’s walls?

Yes! NCFI InsulStar® closed cell foam is strong and structural. Your walls will be more resistant to winds and you’ll notice less creaking and shaking when doors are slammed. NCFI’s Sealite open cell foam is lighter density and not as strong as InsulStar but will still seal your walls and add strength to your home. See our report on Wall Strength for more information.

How long does it take to install spray polyurethane insulation?

Quite quickly. A single-story building can be fully insulated with spray polyurethane in a day or less. Large buildings with complex design features could take longer.