There are two general categories of Spray Foam Insulation materials; open-cell, low-density (a.k.a. ‘half-pound foam’) and closed-cell, medium-density (a.k.a. ‘two-pound foam’). Both foam categories provide excellent insulation and air sealing. Although both are made using almost identical chemical reactions, there are some inherent physical property differences that often determine which product is chosen for a particular project.

Open-cell spray foam (ocSPF) has an open cell structure where the cells are filled with air. The open-cell structure renders soft, flexible foam, with a density of about 0.5-0.8 pounds per cubic foot (pcf). Still, air is the primary insulation medium in ocSPF, fiberglass, and cellulose. These insulations work by reducing the natural air movement within these materials thereby reducing the ability of the material to conduct heat. The R-value per inch of open-cell foam typically ranges from R3.6 to R4.5 per inch. Unlike fiberglass and cellulose, the fine cell structure of ocSPF makes it air-impermeable at certain thicknesses. The air-impermeability of ocSPF qualifies it as an air-barrier material, dramatically reducing air leakage through the building envelope, significantly lowering the building’s heating and cooling costs. ocSPF, like fiberglass and cellulose insulations, is moisture-permeable, and may require the installation of a vapor retarder in colder climates. .

Closed-cell spray foam (ccSPF) has a closed-cell structure which yields a rigid, hard foam, with a density of 1.8-2.3 pound per cubic foot (pcf), and has been demonstrated to provide a structural enhancement in certain framed buildings. These smaller cells trap an insulating gas, called a blowing agent. This blowing agent has a lower thermal conductivity than still air, and increases the R-value. Typical R-value per inch of closed-cell foam ranges from R5.8 to R6.9* per inch, making it a great choice in applications where clearance is limited. Like ocSPF, ccSPF is also air impermeable at certain thicknesses and can qualify as an air-barrier material. The closed-cell structure of ccSPF makes it water-resistant and is the only spray foam that can be used where contact with water is likely (e.g., below-grade concrete walls, in contact with the ground, or on the exterior side of the building envelope). At a thickness of 1.5 inches, ccSPF has moisture permeance typically less than1.0 perms and no additional vapor retarder is required for most applications.

*Consult product data sheets

Closed-cell foams, by nature, are resistant to water absorption, and are approved by FEMA as a flood-resistant material. Open-cell foams can absorb and retain liquid water at varying rates. It is important to consider the different properties for each foam type for each application.

During application, Spray Foam Insulation, like most site-applied building materials, will release small amounts of chemical compounds into the air. Each manufacturer will provide a time for re-occupancy after completion of the application. Spray Foam Insulation materials and coatings can also give off odors that may be noticeable by some people, but with proper ventilation, these odors should subside. Several Spray Foam Insulation products have been independently tested (ULe GreenGuard, CAN-ULC 774, CA 01350) for the release of volatile organic compounds, and no significant levels have been measured after the prescribed cure periods. One study, performed by the American Medical Association, assessed the toxicity of a number of foam plastic insulation products and concluded that fully-cured polyurethanes present no toxicity problems for humans (the Journal of The American Medical Association, Vol. 245, No. 3.).

Spray Foam Insulation, like many construction materials, is combustible and can ignite when subjected to heat or flame. For this reason, model building codes require that Spray Foam Insulation materials (with some exceptions) must be separated from interior (occupied) spaces by a 15-minute thermal barrier, such as ½” gypsum board. In limited access areas like crawlspaces and attics, an ignition barrier may be permitted in place of a thermal barrier. Prescriptive thermal and ignition barriers are defined in the model building codes, and alternative coatings, coverings, and assemblies may be used.

As a trade association, SPFA, by law, cannot provide information on material or installation costs. In general terms, the installed cost of SPF insulation is greater than that of fiberglass or cellulose insulations, but SPF provides many extra benefits including air barrier and vapor control, as well as improved structural performance. The installed cost of SPF roofing systems is competitive with other roofing systems. Get In Touch with InsulRight for an estimate and specific requirements.

Because of its rigid nature and ability to adhere to many materials, closed-cell Spray Foam Insulation (ccSPF) can provide structural enhancement to framed buildings. Racking strength of certain framed walls, as well as uplift strength of framed roof decks, can be significantly increased with the addition of just 2-3 inches of Spray Foam Insulation.

Before hiring a Spray Foam Insulation contractor, always be sure that the applicator on the job site is properly trained. At a minimum, the applicator should have completed a two or three-day equipment and materials course provided by the Spray Foam Insulation Material Supplier or Distributor. All members of the Spray Foam Insulation crew should have completed the Online Health and Safety Training for Spray Foam Insulation, provided by the Center for the Polyurethanes Industry (CPI) at www.spraypolyurethane.com. Additionally, you may want to consider a contractor with advanced training offered by the SPFA Roofing or Spray Foam Insulation Building Envelope Certification Programs.

Spray Foam Insulation is an ideal product for insulating and air-sealing existing homes. Spray Foam Insulation can be used to create energy-saving unvented attics and crawlspaces that seal against air leakage and bring under-insulated and leaky HVAC ducts inside the conditioned space of the building. In addition, Spray Foam Insulation can be used to insulate and air-seal band and rim joist areas where the framing meets the home’s foundation.

The application of Spray Foam Insulation can produce hazardous levels of airborne chemicals during and just after installation. These chemicals, most notably MDI, will degrade into non-hazardous compounds in a few hours when combined with moisture in the air. Because of these short-term airborne levels, re-occupancy of the work area by other trades or building occupants is typically 24 hours. However, specific re-occupancy time may vary depending on the type of material, the volume of mists and fumes generated, building size and rate of ventilation. Your contractor and their supplier can recommend re-occupancy times based on job-specific conditions. For more information on Jobsite re-occupancy, please refer to the American Chemistry Council’s Center for the Polyurethane Industry (ACC-CPI) website: http://www.spraypolyurethane.org/Reoccupancy

Spray foam, when applied to certain minimum thicknesses (about 1.5” for closed-cell foam and 3.5-5.5” for open-cell foam) will form an air-impermeable, air-barrier material. When properly installed in a well-designed building envelope, SPF plays a key part in creating air barrier assemblies and systems. For more information on air barriers, visit the Air Barrier Association of America (ABAA) at www.airbarrier.org. ABAA provides a material specification for SPF under the ABAA document 07263.

Closed-cell Spray Foam Insulation can be used in combination with other insulation materials such as fiberglass, cellulose and foam board products. These cost-effective hybrid systems use SPF to insulate and air seal and use other insulations to provide assembly R-values that meet energy codes. In colder climates, special design considerations are needed to address potential moisture condensation issues. For more information on using Spray Foam Insulation in hybrid insulation applications, see SPFA’s guidelines on hybrid systems: SPFA-146 Spray Polyurethane Foam for Hybrid Insulation Systems – Climate Zones 1-3 and SPFA-147 Spray Polyurethane Foam for Hybrid Insulation Systems – Climate Zones 4-7

The use of Spray Foam Insulation and roofing systems is permitted by the international model building codes published by the International Codes Council (ICC). Spray Foam Insulation is a type of foam plastic, which is specifically addressed in the International Building Code (IBC) Section 2603, and in the International Residential Code (IRC) Section R316. These sections of the model building codes focus on fire protection requirements for the safe installation of these materials. Many Spray Foam Insulation products have third-party code compliance evaluation reports that detail how specific products may be installed to meet the model building code requirements. Although ICC provides model building codes, states, and local jurisdictions accept different editions or may make changes to these codes before adoption always check with your local building department to confirm which version of the code is being used and specific requirements for the use of Spray Foam Insulation. For copies of or more information about the model building codes, they may be available at your local public library or visit www.iccsafe.org.