Types of Spray Polyurethane Foam Products
Spray polyurethane foam (SPF) is a highly-effective and widely used insulation and air sealant material. However, exposures to its key ingredient, isocyanates, and other SPF chemicals in vapors, aerosols, and dust during and after installation can cause asthma, sensitization, lung damage, other respiratory and breathing problems, and skin and eye irritation.
To create the final SPF insulation or sealant product, a chemical reaction of two component parts has to occur. Chemicals in SPF products leave the gun, nozzle, or straw and form a foam as the chemicals react. Safe work practices should be in place to avoid exposure at every stage of SPF installation.
The chemical components, particularly isocyanates, and related hazards are similar for the various types of SPF products on the market. The polyol blend (side B) of SPF products contains a variety of proprietary chemicals that provide specific performance functions i.e, catalyst, flame retardant etc.
However, the amount of product used, the delivery mechanism, and overall application process differs for each type of SPF product; therefore, the potential for exposure may vary, though there is potential for eye, skin, and inhalation exposure to hazardous chemicals with all types of SPF products. Remember to use the appropriate protection and best practices suited for each type of SPF product.
Types of Spray Polyurethane Foam Products
There are three main types of SPF products, each of which have different application uses, but all the SPF products require the use of protective equipment in order to prevent exposure to isocyanates and other SPF chemicals. See below for more information on the differences and similarities of the SPF products.
For more information on the distinctions between the various spray polyurethane foam products and guidelines that should be followed during application whether you’re a homeowner hiring someone to install spray polyurethane foam (SPF) for you, a do-it-yourselfer, an SPF contractor, builder or weatherization professional, visit the American Chemistry Council’s Center for Polyurethanes Industry Spray Polyurethane Foam Health and Safety website. ![]()
| Information on the Various Types of Spray Polyurethane Foam Products | |||
| SPF Types | Two-component
High-Pressure Open-Cell (low density, half lb.) Closed-Cell (medium density, 2 lb.) Closed-Cell (high density, 3 lb.) |
Two-component Low-Pressure |
One Component Foam
(OCF) |
| Uses |
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Sealant for filling cracks, holes, gaps, and crevices:
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| Applicator | Professional Installer |
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| Container size | 55 gallon drum containers | Typically three to five gallons per container from the system house, but can be purchased in larger containers over the internet or in some retail markets | Available in retail and hardware stores nationwide in a variety of sizes ranging from 12 oz. to 24 oz. cans |
| Engineering Controls | Ventilation and containment practices should be considered to control chemical exposures. Work in "permit-required" confined spaces as defined by OSHA, which may include work in attics and crawl spaces, requires entry procedures, including an entry permit, and training for the workers.
OSHA requires a hierarchy of controls, under which employers must first implement engineering controls where feasible. Consult the safety data sheet for additional guidance on the use of Personal Protective Equipment (PPE) and Respiratory Protection when the use of engineering controls are not feasible or adequate to control exposures. See below for personal protection recommendations for each type of SPF product. |
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| Personal Protection | Personal Protective Equipment:
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Personal Protective Equipment:
Read more information about personal protection when using two-component low pressure kits. |
Personal Protective Equipment:
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| Chemical Composition | SPF products contain approximately 50 percent Side A and 50 percent Side B. This chemical reaction generates heat. Side A contains very reactive chemicals known as isocyanates. Side B contains a polyol, which reacts with isocyanates to make polyurethane, and a mixture of other chemicals, including catalysts (which help the reaction to occur), flame retardants, blowing agents and surfactants. |
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| Variations in Chemical Composition | Open-Cell Blowing Agents: Carbon Dioxide or Water |
Closed-Cell Blowing Agents: HFC-245fa |
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| Application Process | Sides A and B are pumped through heated hoses from supply tanks into a nozzle where the two components react and are spray applied at elevated temperatures (>150°F) and pressure (1200 psi). “Open” cell foam expands more vigorously than “closed” cell foam and should be applied in layers. See photographs below illustrating expansion differences between open-cell and closed-cell SPF. Foam can expand up to 120 times its original volume. After the foam is applied, has expanded, and has cured, it may be trimmed or cut, as needed; this might especially be true for the use of “open” cell foam that may expand beyond the wall. | Sides A and B combined at application site and sprayed on as a stream or bead. After the foam is applied, has expanded, and has cured, it may then be trimmed or cut, if needed. | OCF components are pre-reacted and undergo further reaction with ambient moisture at the time of application (moisture cured). Applied as stream or bead. May be trimmed or sanded. |
| Chemical Exposure Potential | May be exposed to chemicals:
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May be exposed to chemicals:
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May be exposed to chemicals:
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| Hazards |
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| Re-Entry | Some manufacturers estimate that it can take 23 to 72 hours for the foam to fully cure after this type of application, but curing rates can vary. | Some manufacturers estimate that it can take 23 to 72 hours for the foam to fully cure after this type of application, but curing rates can vary. | Some manufacturers estimate that it can take 8 to 24 hours for one component foam to cure, but curing rates can vary. |
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| Open-Cell SPF Two-component “Professional” High-Pressure System: - Low Density - Expands aggressively - Dries soft - Lower R-value (~ 3.5 per inch) *Photo Courtesy CertainTeed |
Closed-Cell SPF Two-component “Professional” High Pressure System: - High Density - Expands less aggressively - Dries rigid - Higher R-value (~ 6.5 per inch) *Photo Courtesy CertainTeed |
Information on Other Insulation Products
For information on other Insulation Products, visit the Department of Energy's Energy Savers Types of Insulation, the Occupational Safety and Health Green Jobs website or the ENERGY STAR® Air Seal and Insulate website. Read more information on the ENERGY STAR® program as it relates to SPF.
Spray Polyurethane Foam (SPF) Site Navigation
Free Online Training Available!
Applicators and helpers:Receive free basic online training
available on the American Chemistry Council’s Center for Polyurethanes Industry SPF Health and Safety website for preliminary information. Applicators should also receive classroom and hands-on instruction on the safe use of SPF offered by the Spray Polyurethane Foam Alliance Accreditation Program
and SPF system houses.
Health Risks and Alerts on Isocyanates
Isocyanates, are potent eye, skin, and respiratory irritants, reported to be the leading attributable chemical cause of work-related asthma.
Isocyanates are powerful sensitizers that can trigger a severe and potentially fatal asthma attack in sensitized persons if exposed to even very low levels of isocyanates.
The National Institute for Occupational Safety and Health (NIOSH) issued two Alerts to prevent asthma and death from exposures to isocyanates:
- NIOSH ALERT, Preventing Asthma and Death from MDI Exposure during Truck Bed Liner and Related Applications.
- Preventing Asthma and Death from Diisocyanate Exposure.
Exposures to isocyanates should be reduced to the lowest possible level.



