1. What are the differences between open-cell vs. closed-cell SPF insulation?There are two general categories of SPF 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 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 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 exterior side of the building envelope). At a thickness of 1.5 inches, ccSPF has a moisture permeance typically less than1.0 perms and no additional vapor retarder is required for most applications.

    *Consult product data sheets

  2. Does SPF absorb water?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.
  3. Does SPF emit volatile organic compounds after installation?During application, SPF, 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. SPF materials and coatings can also give off odors that may be noticeable by some people, but with proper ventilation, these odors should subside. Several SPF products have been independently tested (ULe GreenGuard, CAN-ULC 774, CA 01350) for 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.).
  4. What fire protection measures (thermal or ignition barriers) are required for SPF?SPF, like many construction materials, is combustible, and can ignite when subjected to heat or flame. For this reason, model building codes require that SPF 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.
  5. What are the structural benefits of closed-cell SPFBecause of its rigid nature and ability to adhere to many materials, closed-cell SPF (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 SPF. For more information, please contact SPFA to obtain detailed reports.
  6. How do I know a SPF contractor is properly trained or certified?Before hiring a SPF contractor, always be sure that the applicator on the jobsite is properly trained. At a minimum, the applicator should have completed a two or three day equipment and materials course provided by the SPF Material Supplier or Distributor. All members of the SPF crew should have completed the Online Health and Safety Training for SPF, provided by the Center for the Polyurethanes Industry (CPI) at www.spraypolyurethane.com .
  7. Is SPF suitable for residential retrofit insulation applications?SPF is an ideal product for insulating and air-sealing existing homes. SPF 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 SPF, can be used to insulate and air-seal band and rim joist areas where the framing meets the home’s foundation.
  8. Should access to the work area be restricted during and immediately after spray foam installation?During and immediately following spray foam applications, fumes and mists are generated that can be hazardous to your health. Access to the work area during this time should be restricted to personnel wearing appropriate personal protective equipment (PPE), including respirators, and whose job responsibilities require them to be in the area.
  9. What is the difference between low-pressure and high-pressure SPF application?Low pressure SPF applications fall into two categories, sealant foam and insulation foam:
    1. Low Pressure Sealant foam consists of one-component aerosol cans and two-component spray foam kits.One-component SPF aerosol cans typically hold from 0.5 to 2 lb. of SPF and are used for sealing cracks, crevices and small holes.  They are available at retailstores and are popular for do-it-yourself (DIY) projects.

      Low pressure two-component kits consist of small A- and B-side pressurized cylindersconnected to plastic hoses and a disposable spray nozzle or gun. They are most commonly used by SPF contractors  for air sealing,patching and repairing of small areas of spray foam (up to 100 bd. ft).  The two-component kits can range from 5 to 30 lb. of material.

    2. Low Pressure Insulation SPF systems consist of refillable cylindersof A- and B- components in sizes ranging from 50 to 100 lb. of material. The cylindersare typically pressurized to around 200 to 250 psi with a pumping capacity between 10-15 lb. per minute with a maximum hose length of up to 200 feet. Most systems are unheated and use equipment specific to the SPF system.

    High Pressure SPF systems consist of A-and B components being transferred from unpressurized 55 gallon drums or larger tanks and pumped through a proportioner that heats and pressurizes the materials. The materials reach pressures ranging from 800 to 1500 psi and temperatures of 100-140°F as they pass through heated hoses and are mixed at the spray gun. Pumping capacity varies considerably depending on the size of the proportioner and can range from 10 lb. per minute to more than 45 lb. per minute throughhose lengths up to 350 ft.

  10. Can SPF be used as an air barriers?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 ABAA document 07263.
  11. Can SPF be used with Other Insulations (Hybrid Insulation Systems)?Closed-cell SPF 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.
  12. Is SPF permitted by the building codes?The use of SPF insulation and roofing systems is permitted by the international model building codes published by the International Codes Council (ICC). SPF 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 safe installation of these materials. Many SPF products have third-party code compliance evaluation reports that detailhow 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 SPF. 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.