Among the listed materials,builder’s grade plywoodis the most resistant to water damage according to the IICRC WRT body of knowledge. Plywood is composed of cross-laminated wood veneers bonded with water-resistant adhesives, giving it greater dimensional stability and moisture tolerance compared to other engineered wood products.
Tempered hardboard, medium-density fiberboard (MDF), and particleboard are all highly moisture-sensitive. These materials rely on compressed fibers and resins that rapidly swell, lose structural integrity, and experience irreversible damage when exposed to water. The WRT manual identifies MDF and particleboard as particularly vulnerable, often requiring removal even after brief exposure.
Builder’s grade plywood, while not immune to damage, can often tolerate wetting, dry effectively, and regain much of its structural performance if contamination conditions permit. This makes it more likely to be restorable under Category 1 or some Category 2 conditions, depending on exposure duration and degree of damage.
The WRT curriculum uses this comparison to help technicians make informed decisions during initial inspection and material evaluation, reinforcing that not all engineered wood products behave the same when wet.
