Spray Polyurethane Foam, or SPF, is a high-performance insulation material commonly used in homes and buildings of all types. SPF is particularly known for its ability to help improve the health, comfort, and energy efficiency of a home. The use of the material can dramatically reduce the energy costs associated with heating and cooling while helping to keep the home interior comfortable year-round, even as the seasons change. SPF has been used as insulation in homes and buildings for decades. As a new homeowner or prospective buyer, you may have questions about the material and how well it works. This guide will help you better understand why SPF is a leading choice of insulation by homeowners.
Spray Foam Insulation


SPF is a type of polyurethane. Polyurethane was invented in the 1930s and, has since become utilized widely and safely in several different applications. In fact, we all interact with polyurethanes daily. They are a preferred material used in furniture, mattresses, automobiles, airplanes, clothing, shoes, sporting and camping equipment. Additionally, rigid polyurethane foam is used to insulate refrigerators, freezers, coolers, and hot water heaters. With so many uses for polyurethane, it is hard to imagine life without it.


SPF acts as a single-material solution for thermal, air, vapor*1 and water* vapor transmission through the home’s building envelope, or enclosure. Think of the enclosure of the home as what a set of clothing is for the human body on a windy, damp winter day. A sweater (fibrous insulation) provides insulation (Rvalue) to retain body heat – but it does not stop wind (air movement) or control moisture. You would need a thin waterproof windbreaker (air barrier and vapor retarder) to block the wind as opposed to just wearing a sweater. SPF insulation is the only insulation inside stud walls that can provide R-value, air barrier and vapor barrier in a single product. As a thermal insulator, SPF is one of the highest performing insulations available.

Energy Saving With Spray Foam Insulation

Spray applied by professional installers, the material forms in-place. It fully adheres and initially expands to eliminate cracks and gaps that leak air or water vapor. It may also be applied in a continuous layer, eliminating most thermal bridges caused by framing. These thermal and air-sealing qualities of spray foam are what directly result in lower home energy bills. Closed-cell SPF, a denser and more rigid version of the material, also provides structural enhancement and can qualify as both a water vapor retarder, a water-resistant insulation and secondary water barrier. It may be applied on the interior of walls, as well as along exterior walls as continuous insulation – above or below grade.

A house on stacks of bills


The properties of SPF insulation can help:

• Control your indoor air quality

• Increase your indoor comfort in all rooms

• Save 30% or more on heating and cooling costs

• Keep your home cooler in summer & warmer in winter

• Reduce pollutants, allergens & pests entering your home


SPF insulation comes in two basic types, and both can be used in any climate zone. All SPF insulation provides air sealing and insulation. Open-cell SPF, ProFILL, is generally less costly than closed-cell foam because it does offer fewer performance characteristics. The higher R-value per inch of closed-cell foam may be more suitable in tight spaces and justify the investment. Closed-cell foam, ProSEAL also provides vapor retarder and water-resistant performance needed in certain applications, as well as structural strengthening of the home. 

Illustration of where spray form may be applied on a house


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MYTH #1: SPF is flammable. 

False...Cured SPF and the chemicals used to make SPF are not flammable. They are considered ‘combustible’, which like many common building materials, including wood, means it requires a higher than normal temperature to ignite. And in some cases, spray foam can improve fire safety by blocking flame spread inside frame walls.

MYTH #2: SPF emits toxic chemicals.

False...Following proper installation and curing, SPF does not outgas toxic chemicals. The SPF can help prevent unwanted infiltration of pollutants, allergens, and moisture. Combined with proper mechanical ventilation, SPF can improve indoor air quality, Installers wear protective equipment mainly because of short-term chemical hazards during and within a few hours after application.

MYTH #3: SPF creates a home envelope that doesn’t allow a building to ‘breathe’. 

True...which is good. SPF prevents the infiltration of unwanted moisture and exfiltration of conditioned air which, in turn, can reduce condensation that causes mold, mildew, poor indoor air quality, rot or corrosion of the home. A properly designed spray foam home will also include controlled ventilation to bring in small amounts of outside air to displace odors from normal homeowner activity while minimizing energy loss.

MYTH #4: SPF increases termite infestations. 

False...SPF is not a food source for wood-destroying organisms like termites. SPF seals cracks and gaps in the home, reducing paths for entry of insects and other pests. SPF also controls the infiltration of unwanted moisture, which termites need to thrive. When properly applied, SPF can be installed to allow for regular visual termite inspections by pest management professionals, providing no greater risk to termite damage than any other cavity insulation.