On July 5, 2017, the U.S. Environmental Protection Agency (EPA) withdrew its ruling that would have delayed compliance dates for formaldehyde emissions standards on specific composite wood products. The EPA will instead proceed with a final rule based on its proposed rule published on May 24, 2017 after considering all public comments. APA along with other wood trade associations had submitted public comments urging that the EPA implement the formaldehyde standards at the earliest possible timeline. Under the new EPA formaldehyde standard, prefabricated wood I-joists, wood structural panels, and other structural engineered wood products, such as laminated veneer lumber (LVL), are exempt due to their very low emission rates.
The EPA federal regulation that definitively addresses formaldehyde emissions from composite wood products sold in the United States was signed into law in July 2010 with extensive bilateral support and the support from APA and other wood trade associations. The implementation rules were first published in the Federal Register on Dec. 12, 2016, by the EPA following extensive study and discussions with wood product industry representatives and public comment. The ruling was delayed when, in February, President Donald Trump issued an executive order to alleviate unnecessary regulations and to require the EPA to evaluate existing regulations and to identify regulations that should be repealed, replaced, or modified.
After review of the public comments, including many from the wood products industry, it was determined that the initial rule was sound and that the Direct Final Rule should be withdrawn. The new EPA ruling will lead to labeling of compliant composite wood products as soon as compliance can be achieved and reduce the unnecessary burden for panel producers, fabricators, distributors and retailers who want to roll out compliant inventory.
The regulation is intended to ensure that all composite wood panels and the finished products containing them – both domestic and imported – meet the world’s most stringent standards for formaldehyde emissions. The standard defines composite wood products as particleboard, medium density fiber board (MDF), and hardwood (decorative) plywood. The standard explicitly exempts structural wood products, such as prefabricated wood I-joists.
What’s in a prefabricated wood I-joist?
Prefabricated wood I-joists are strong, lightweight, "I" shaped engineered wood structural members that are manufactured to meet demanding performance standards. The joists are comprised of top and bottom flanges, which resist bending, jointed with structural panel webs, which provides shear resistance. The flange material is typically laminated veneer lumber (LVL) or solid-sawn lumber, and the web is made with structural plywood or oriented strand board (OSB), with OSB being the most common web material used. The combination of structural characteristics results in a versatile, structural efficient, and economical framing member that is easy to install in construction projects.
Are I-joists new to residential construction?
No, prefabricated wood I-joists were first introduced in 1969, and their use and popularity in residential construction has grown steadily. In the five-year period from 2011 to 2016, 2.2 billion lineal feet of wood I-joists were used in single-family residential construction.
Wood I-joists are manufactured, evaluated, and trademarked by accredited independent third-party product certification or inspection agencies in accordance with ASTM D5055, and are used extensively in residential floor and roof framing. They are ideal for long spans, including continuous spans over intermediate supports. Builders report that I-joists are straight and true, which makes it easier to avoid crowning and maintain a level framing surface.
Do prefabricated wood I-joists emit formaldehyde?
Formaldehyde occurs naturally in all wood (even trees in the forest!), and some additional formaldehyde is present in the adhesives that are used in I-joists and other engineered wood products. The emission levels from structural wood products, however, are so low that prefabricated wood I-joists, structural plywood, and oriented strand board are exempt from the stringent requirements of the California Air Resources Board (CARB) Air Toxic Control Measure (ATCM) for composite Wood Products and the EPA ruling, which is a technical equivalent to the CARB regulation.
“APA ran a study and found formaldehyde emission levels in I-joists were similar to background air levels,” said Steve Zylkowski, Quality Services Director for APA-The Engineered Wood Association. “Our findings validated the decision by CARB and the EPA to exempt prefabricated wood I-joists from the rulings,” he added.
What about the adhesives?
The OSB and plywood products that are used in I-joist webs are manufactured to meet stringent product standards, including Voluntary Product Standard PS 1, Structural Plywood, and Voluntary Product Standard PS 2, Performance Standard for Wood Structural Panels. Because these wood structural panels are designed for construction applications governed by building codes, they are manufactured only with moisture-resistant adhesives that meet Exterior or Exposure 1 bond classifications. The adhesives used in these panels create chemically stable bonds during hot pressing that results in moisture resistance. The same bond stability restricts emissions of formaldehyde. Similarly, the adhesives used in the finger-jointed lumber and LVL flanges, and for the web-flange connections are required to meet stringent strength and bond durability requirements. As a result, wood structural panels and prefabricated wood I-joists have such low formaldehyde emission levels that they were exempted from the CARB and EPA regulations.
Prefabricated Wood I-Joists and Fire Protective Coatings
Several manufacturers offer wood I-joist products that have an added fire-protective layer or proprietary coating. APA does not evaluate those factory- or field-applied coatings being sold in the U.S. A factory-applied proprietary coating must meet ICC-ES Acceptance Criteria AC14, which includes fire endurance and coating durability provisions, and be recognized by a code evaluation report. Additional information about the fire-protective coating composition and performance is available from the manufacturers.