For non-structural, high-volume applications (like packaging or disposable formwork), EPS (Expanded Polystyrene) is the cheapest by volume. However, in structural markets, PET Foam (Polyethylene Terephthalate) is the current industry sweet spot. While it is slightly more expensive per board foot than basic PU, it offers thermoformability (can be heated and shaped without crushing), 100% recyclability, and excellent fatigue resistance, reducing the total life-cycle cost.

