What You Donít Know About Foam

Posted by Macie Schreibman on June 23, 2011
What You Donít Know About Foam
It seems that some materials being used by contractors during energy retrofits may not meet code or manufacturer's requirements for an ignition or thermal barrier, according to Pure Energy. In this case, the company, which is dedicated to quality assurance in the home improvement industry, is referring to the use of rigid or spray foam products. “When some building and retrofit products burn, they can release potent fumes that can make people sick or die," says Pure Energy founder Tamasin Sterner.
Some plastic foams, both rigid and spray, require being covered by an ignition or thermal barrier after installation. Others do not. The deciding factor about whether or not they need to be covered is the installation location, whether or not the product has a fire rated barrier already built into the product, and for some products, the product thickness. (The thicker the product, the higher the hazard if it burns, so some thicker products need a covering).
The following is a breakdown of what contractors need to know, courtesy of Pure Energy:

Spray Foams
  • When applied to sill plates and headers, spray foams are permitted to be installed without a thermal barrier when they meet the installation thickness of up to a maximum of 3.25 inches, density range of .5 to 2.0 lb/cu ft, and tested in accordance with ASTM E 84.
  • When applied in small quantities in attics, crawl spaces, basements and other areas of the home to fill gaps and cracks, products such as Dow’s Great Stuff (single component polyurethane) spray foams can be used without a thermal barrier providing manufacturer installation specs are followed with typical sealing widths of 1-5/16 inch maximum, and nominal foam thickness not to exceed 3 inches.
  • When applied in large quantities to areas such as attic roof decks, crawl and basement walls, when using two-part polyurethane, each product must be evaluated for location use and requirements for coverings, and the coverings must be evaluated to be sure they meet the requirements as a barrier.
  • Based on area usage (storage, heating appliances, etc.,) and codes, an ignition and/or thermal barrier may be needed—either spray product, or drywall, or other approved covering.
  • When applied to ducts in attics and crawl spaces an ignition barrier may be needed dependent upon product and manufacturer testing.  Spray polyurethane foam is permitted to be applied to duct joints and seams without additional covering.
Rigid Foams
  • In some cases, rigid boards may be used in unfinished attics or crawl spaces without covering as long as they are not over a certain thickness. 
  • When applied in attics, most must have a barrier over them unless the attic is used for service of utilities only.  In other words, most rigid foam boards don't have to have a barrier over them if they are used in an unfinished attic that is used for utility service only.  If the attic is used for storage, heat producing appliances or if it is finished, most rigid boards need to be covered with an ignition barrier or thermal barrier. 
  • Most rigid boards are not permitted to be used in unconditioned or conditioned basements without a thermal barrier.
  • When used in crawl spaces, most rigid boards don't have to be covered if the crawl space is used for utility only.  However, if the crawl space is used for storage or heat producing appliances, some rigid boards must be covered.
  • When used in the living spaces, most rigid boards must be covered.
Along with the above, it is recommended that all contractors read the literature available from the product manufacturer to be sure they are using the correct product for the location and application. 

"As QA inspectors for several weatherization, conservation, and efficiency programs, Pure Energy must know as much as possible about fire, electrical, building and other codes.  We also must know about products and where they are allowed to be used in buildings, with or without ignition or thermal barriers that are required to protect people in the case of a fire," Sterner says.  "Code books are hard to read and understand!  We are doing our best to clarify the issues, and we believe we are on the cutting edge with this information."

For more information, download the entire whitepaper, “Air Sealing and Insulating Using Rigid or Spray Foam Products” here.

Pure Energy uses a coaching model for all of its services, whether it be QA inspections for programs, audits, or teaching. Since 1987, Pure Energy has served over 40,000 households.

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