Composite wood products are uniform and reduce waste, but they’re not problem-free. Every engineered wood product uses adhesive to bind together its wood particles, and these binding agents can off-gas (emit) toxins into your home. Phenol formaldehyde (PF) is a probable carcinogen found in the majority of engineered wood products. Luckily, off-gassing will decrease over time, especially in well-ventilated areas, but it’s a good idea to allow these products to “air out” before you occupy your new home.
Be alert for products that contain urea formaldehyde (UF), which off-gases at a higher rate than its cousin PF. UF is found in many pressed wood products made for indoor use, like particleboard or medium-density fiberboard. To avoid this more noxious binder, use exterior-grade plywood, even indoors, because it typically will contain the more benign PF.
Formaldehyde-free options are becoming available. PMDI is a waterproof, polyurethane-type binder that’s moving into the marketplace. Although it’s an attractive option in terms of off-gassing, the adhesive is quite toxic until it cures, posing a threat to factory workers’ health.