Green Building – Composite Lumber

Tom Sulcer, Creative Commons 

Did You Know?

  • Composite wood is used in the manufacture of cabinets, countertops, doors, flooring, and many other products.  Its chemical binders often contain formaldehyde, a carcinogen, developmental toxin, endocrine disruptor, and respiratory irritant.

  • When selecting wood products based on health, solid wood has the lowest levels of formaldehyde.

  • If solid wood is not possible, look for products labeled as NAF (No Added Formaldehyde) and ULEF (Ultra-Low Emitting Formaldehyde).

Composite Lumber

A Veneer of Safety?

Composite, non-structural, wood is used in the manufacture of cabinets, countertops, doors, flooring, flooring underlayment, furniture, moldings, and shelving.  While structural lumber such as studs and sheathing is essential to most homes, it is usually not directly exposed to the indoor air.

These composites use chemical binders to mold wood particles and chips into functional boards, and these binders often contain formaldehyde.  This chemical is carcinogenic, a developmental toxin, an endocrine disruptor and organ toxicant, and can cause respiratory problems.  Its symptoms include dizziness and sinus inflammation linked to multiple chemical sensitivity.  There is no safe threshold of exposure.

Responding to public health concerns, the lumber industry has complied with regulatory standards limiting formaldehyde emissions.  Voluntary standards lower emissions even more.  Below is a ranking of wood products reflecting their effect on the indoor environment.

Note that there is a secondary ranking within each class that contains formaldehyde.  Composite hardboard has lower emissions than particle board, which in turn has lower emissions than medum density fiberboard due to the percentage of chemical binders used in each product.  Also worth noting is that there is no such thing as formaldehyde-free wood.  Wood generally has a small amount of the chemical that is naturally occurring.

Solid Wood – Solid wood, where feasible, is a preferred option to composites of any kind.  If this class of materials is used, it is preferable that finishes or coatings be applied during manufacturing to limit VOC offgassing onsite.

No Added Formaldehyde (NAF) & Soy-Based Resins  Some composite lumber products use formaldehyde-free binders.  These include methylene diisocyanate and soy-flour mixed with petrochemicals.  While environmentally preferable, isocyanates are asthmagens, and some petrochemicals are inherently toxic in their own right.

Moreover, some retail composite products are so complicated that one part of the product can be labeled NAF while another part still contains the chemical.

Ultra-Low Emitting Formaldehyde (ULEF) – This is a voluntary standard that goes above minimum national standards.  The ULEF standard results in an emissions reduction of at least 11% in particleboard, 18% in medium density fiberboard, and 15% in thin medium density fiberboard.

National Formaldehyde Emissions Standard­ – Beginning in 2009, the California Air Resources Board (CARB) required that all composite lumber products sold in the state limit formaldehyde emissions to standards verified by third parties.  Between 2010 and 2012, stricter Phase 2 (“CARB 2”) standards were put into effect.  CARB 2 products became a default rating for green building programs around the country attempting to improve indoor air quality.  These standards were estimated to have lowered Califonia formaldehyde emissions from composite lumber by 58%.

In June of 2018, the U.S. Environmental Protection Agency adopted (with minor revisions) CARB 2 standards for the entire U.S. 

Environmental/Health Ratings for Composite Wood Products

Various agencies and organizations rate composite wood product emissions differently.  Some analyze them as assembly materials; others certify retail products.

California Air Resources Board

The Board certifies composite material and product manufacturers that meet the more rigorous NAF and ULEF standards for sale in the state.

Composite Panel Association

The Association lists composite wood product manufacturers that comply with NAF and ULEF standards.

Eco-Certified Composite (ECC) Sustainability Standard

This is another green product initiative sponsored by the Composite Panel Association.  In addition to not exceeding national formaldehyde emission standards, products must meet at least 3 of 5 other environmental criteria: a net-zero carbon footprint; use of local and renewable resources; recycled content; efficient use of raw materials; and sustainable wood sourcing.


This certification system administered by Underwriters Laboratories measures for VOCs emitted from many product categories, including cabinets, countertops, and doors (wood, agrifiber, and metal).   It has two tiers: its standard GREENGUARD rating; and its premium GREENGUARD Gold certification.

Indoor Advantage Gold

Scientific Certification Systems, Inc. is a private company now operating as SCS Global Services.  It certifies third-party verifications of environmental claims.  It has rated several composite-wood molding products for low air emissions.

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