What Composite Wood to include in Low-Emitting Materials
Green Building Team on November 28, 2018
The LEED v4 BD+C and LEED v4 ID+C Indoor Environmental Quality (EQ) credit Low Emitting Materials uses the definition of Composite Wood per California Air Resources Board (CARB) 93120 Composite Wood Products Airborne Toxic Control Measure (ATCM) which includes hardwood plywood, particleboard, and medium density fiberboard. Therefore, it excludes hardboard (high density fibreboard), structural plywood, structural panels, structural composite lumber, oriented strand board (OSB), glued laminated timber, prefabricated wood I-joists, and finger-jointed lumber.
Similarly, LEED Interpretation #10466 clarifies that structural engineered wood products do not need to meet the general emissions evaluations requirements. Structural wood products do however have to be:
- made with moisture resistant adhesives meeting ASTM 2559;
- have no surface treatments with added urea-formaldehyde resins or coatings, and;
- have a certificate of compliance with the applicable industry standard, as outlined by product type (e.g. plywood, OSB, etc.). See LEED Interpretation #10466 for full list of product type requirements.
What about softwood plywood? In Canada softwood plywood is quite common. Consider the definition of hardwood plywood per CARB 93120 ATCM:
“’Hardwood plywood’ (HWPW) means a panel composed of an assembly of (A) hardwood layers or plies of veneer or (B) veneers in combination with a platform consisting of lumber core, composite core, a special core material, or special back material, joined with an adhesive. The face veneer may be composed of a hardwood or decorative softwood species (ANSI/HPVA HP-1-2004)…”[emphasis added]
The definition references the American National Standards Institute (ANSI)/ Hardwood Plywood and Veneer Association (HPVA) standard for hardwood and decorative plywood, which allows the use of softwood face veneers in the definition of hardwood plywood. Therefore, softwood plywood is not exempt, and is subject to CARB 93120 ATCM, and the Composite Wood Evaluation requirements of LEED v4 EQ credit Low Emitting Materials, which is to have ultra-low-emitting formaldehyde (ULEF) resins or no added formaldehyde resins.