Plywood has been a go-to material because it generally works and the price is right. There are always comparisons of plywood to particle board, but at the end of the day, both are susceptible to warping. In that regard, 3M Co. has developed 3M Reinforced Polyurethane Foam, a said to be lightweight, rot-resistant alternative to plywood with no risk of warping.
The foam boards have high strength because of their fiberglass reinforcement which lets them go into structural and semi-structural applications. Because the boards are waterproof and strong, they target applications that include marine, transportation and general construction.
One of their advantages over plywood is a weight savings ranging from 30 to 60%. The reinforced foam is available in five densities ranging from 15 to 26 lb/ft3. (For comparison, plywood densities typically range from 30 to 43 lb/ft3.) The reinforced foam is sold in 4x8-ft sheets and provides users with a straight, level board that is easy to work with. 3M’s reinforced foam can be shaped with common wood working tools and provides a better adhesion than wood because of its low moisture content.