Editor's Update: As expected, LEED Interpretation #10250 was revisited by USGBC in its 4/1/13 release. This article has been updated to address that revision. 

Composite wood products made with added urea formaldehyde (UF) are one of the few products that LEED has consistently banned under its longstanding IEQc4.4: Low-emitting Materials credit. However, LEED Interpretation #10250, issued January 1, 2013 (revised April 1, 2013) and applicable to all LEED 2009 projects, as well NC-v2.2 and other systems, now allows for the use of urea in combination with melamine formaldehyde (MF) in certain circumstances. The Interpretation was meant to clarify longstanding questions about the use of MF resins. Products that use MF resins without any urea are allowed, per the original credit language. However, many MF-containing products have a urea component. The Interpretation addresses those products as follows: 

• Urea, when used as part of a melamine-urea-formaldehyde (MUF) resin or as a formaldehyde “scavenger,” is allowed as long as the composite wood product meets California Air Resource Board (CARB) Airborne Toxic Control Measure (ATCM) 93120 requirements for ultra-low-emitting formaldehyde resins (ULEF).

Note that in the original January 1, 2013 Interpretation composite wood products that used urea as a scavenger were not allowed, even if they met ULEF requirements. The April 1, 2013 revision reversed that decision.

According to André Verville, research and technical director at Uniboard, maker of ULEF melamine particleboard and other composite wood products. Urea itself “scavenges” leftover free formaldehyde from the MF reaction and converts it into another form, which should actually reduce formaldehyde emissions from the product, he explained, when compared with MF resins that don’t use urea scavengers.  Verville said that pure MF products could have up to three times the emissions of those using the scavenger.

The chemistry of these resins is complicated, and there have been concerns that formaldehyde could be released over time from products using urea as a scavenger—particularly in hot, humid climates. But the ULEF performance-based policy requiring emissions testing was later deemed sufficient enough to address these concerns. Design teams looking to avoid all formaldehyde from MUF composite wood products should look to those made using polyurethane resins.