
Chemistry
Capped composite has wood. Capstocked PVC doesn't. Everything else flows from there.
Capped composite = wood fibre (hardwood flour, bamboo, or recycled wood) + recycled plastic (HDPE or PVC) + a polymer capstock that surrounds the board. The wood content is what makes a composite a composite — it gives the board weight, dimensional stability, and a grain that prints naturally. Modern capped composites at TUDS run 30%–60% recycled wood with the rest being plastic and cap.
Capstocked PVC (often called "cellular PVC") = no wood at all. The core is foamed PVC for weight reduction, with a PVC or PMMA capstock fused on top. Because there's no organic substrate, there's nothing for mould or rot to attach to — and nothing to absorb moisture. That's the chemistry advantage that drives most of PVC's downstream durability claims.
One nuance: Eva-Last uses a bamboo-infused PVC composite — wood content is bamboo (regrows ~50× faster than hardwood) and the plastic is PVC, not HDPE. So Eva-Last sits between a traditional capped composite and a pure PVC board. It's still a composite (it has organic content) but the chemistry is closer to PVC than wood-flour composites are.

“The wood-versus-no-wood distinction is the only one that actually matters at the chemistry level. Everything else — heat, scratch, fade — is downstream of what the cap is made of, not whether there's wood inside.”





