Spray Polyurethane Foams

One of the current cutting-edge advances in home energy conservation is the use of spray polyurethane foam insulation. Although the chemistry has been around since the 1940s, the past ten years have seen the application expand in commercial buildings and high-end homes. Spray foam is applied to the structural elements of a house – often on the attic roof deck, on foundation footings, and within exterior wall cavities – to provide insulation, act as a vapor barrier, and reduce noise transmission. While most applications are for newly constructed buildings, spray foam may also be used to retrofit older buildings and homes.

What is Spray Foam?

The end product of spray foam is a rigid foam produced by an exothermic (gives off heat) chemical reaction between a polyol resin, flame retardants, and an isocyanate. The insulation expands 30 to 50 times its original volume as it is applied and permanently adheres and bonds to applied surfaces. Spray foam products are either closed-cell or open-cell, depending on the application. Both act as thermal barriers; but closed-cell foam is denser and acts as a vapor barrier, allowing air but not moisture to pass through.

In traditional houses, the attic is designed to be cold during the winter to reduce the potential for ice dams. When spray foam is applied in an attic, it becomes part of the heated structure, reducing the potential for thermal bridging and condensation. This barrier provides a high  degree of insulation (approximately R-6 for each inch of foam). U.S. Department of Energy studies show that 40% of a home’s energy consumption results from air infiltration. Spray foam eliminates some of the drawbacks of traditional insulation, such as fiberglass or blown-in cellulose, but is considerably more expensive.

Most spray foam products are typically sold through distributors. They are applied by independent installers, often hired by the property owner. With the interest in energy conservation and availability of grant money, a number of weatherization companies have been created to serve this market.

Are Spray Foam Products Hazardous?

Manufacturers state that when the products are properly installed, they become completely inert once they cure. One manufacturer attributes any problems to human error during the installation process, stating “what we find in our investigations is the applicators at some level can make an error”. The company urges property owners to ask for proof of qualifications and training from installers when considering spray foam and selecting an installer.

In the past several years, concerns have been expressed about the safety and efficacy of spray foam products. The  Environmental Protection Agency has taken a special interest in the subject. Their website has a link to information on the products and states “the potential for off-gassing of volatile chemicals from spray polyurethane foam is not fully understood and is an area where more research is needed”.

Isocyanates are strong irritants to the gastrointestinal and respiratory tracts. Inhalation of the vapor or particles of foam dust can cause a sensitization reaction, making exposed individuals susceptible to asthma attacks with each subsequent exposure. The polyol resins may contain quantities of formaldehyde and other aldehydes, as well as volatile organic compounds.

If the material is not mixed in correct ratios, applied at too high or too low a temperature or in too thick a layer, or installed improperly by an untrained or inexperienced person, the foam may not properly cure and could continue to off-gas for extended periods…of months or even years.

There are many factors that affect how quickly the foam cures – including type and thickness of foam, condition of mixing equipment, air temperature and humidity, temperature of the components, and the installer’s training and experience. Questions have been raised about the level of training provided by the manufacturers to distributors or installers who are usually independent contractors.

In June 2013, OSHA issued the creation of a Special Emphasis Program for isocyanates, such as those used in spray foam products. This program is directed toward employees that install the products and lays out a set of recommendations for safe handling – including respiratory protection, protective equipment, ventilation, and, most importantly, proper training and certification.

Does Spray Foam Burn?

In addition to health-related issues, a secondary concern is flame propagation and smoke damage. Most spray foam products contain flame retardants such as 1-chloro-2-propyl  phosphate (TCPP) or Tris. The  products have to meet strict guidelines for smoke and flame spread. Treated, spray foam products will not ignite. In the presence of an open flame and heat, spray foam may slowly smolder, which can produce copious quantities of acrid black smoke.

Occasionally, when the foam is applied to surfaces too quickly or in too thick a layer, the heat given off by the chemical reaction may be sufficient to cause charring and ignition of structural wood components, resulting in structural fire damage. The National Association of State Fire Marshalls has produced a report, “Bridging the Gap, Fire Safety and Green Buildings: A Fire and Building Safety Guide to Green Construction”. This report identifies some of the difficulties in fighting building fires that use green construction techniques such as spray foam.

Managing the Risk

Insurance companies may provide general liability, environmental liability, and/or errors and omissions coverage for spray foam manufacturers, distributors or installers. They may also provide property insurance for commercial buildings and homeowners.

There are a growing number of class-action lawsuits filed against the manufacturers, distributors and installers of the foam components – claiming adverse health effects  including chemical asthma and sensitization, as well as chronic odors that make a   property unusable. As of the summer of 2013, class-actions have been filed in Connecticut, Florida, Michigan, New Jersey, New York, Pennsylvania, and Wisconsin, with similar actions expected in Arkansas and North Carolina. In most cases, it was reported that the homeowners were either in their homes at the time the foam was sprayed or came home immediately afterward. In one such case against a manufacturer, the plaintiffs state spray foam “remains toxic after installation because either as designed it is impossible to become inert and non-toxic even under optimal conditions, or proper installation is nearly impossible given the exacting set of installation requirements and inadequate training and installer certification methods”.

The exact number of lawsuits filed is unknown; but given the trend and recent media publicity, they are likely to continue. One primary question raised is who has the liability – the manufacturer, the distributor, the installer, or all three. In Connecticut, there is currently a bill (HB5908) that addresses the need for professional certification in the spray foam industry. There is also an ANSI/ISO accredited professional certification program under development.

In cases where there is product failure or improper installation, the remediation options are limited. The cured foam bonds or adheres to structural framing elements. Where foam has been sprayed into exterior wall    cavities, the wall covering must be removed to expose the foam. The cured foam may be scraped out or treated by blasting with dry ice; however this process is expensive and time-consuming and can produce a lot of smaller foam particles that spread through the building and air handling system. A second option is to cut and remove the treated structures, up to and including the entire roof. This requires careful project management to replace the roof and make the building weather-tight.

Since spray foam is a high value-added product, residential properties are likely to be large and expensive…and either of these removal strategies may cost several hundred thousand dollars. In commercial properties, costs are likely to be considerably more. The third and final option is to consider the property a total insurance loss.

Of course, these cost estimates do not include contents replacement, interruption in use of the property, temporary housing, business interruption, relocation expenses and personal injury. Add to this cost, the retention of law firms, hiring of experts, air testing and other expenses, and the potential exposure and liability may be considerable.

HETI: Experienced EHS Professionals

HETI has extensive experience in supporting our clients through a comprehensive range of environmental health & safety (EHS) support services. Our staff of industrial hygienists and environmental scientists can help manage the complexities and risks presented by spray foam…as well as other new and challenging environmental issues.