What material usually covers the outside of a modern surfboard?

Fiberglass usually covers the outside of a modern surfboard.

A conventional surfboard is made by shaping a lightweight foam blank and then laminating it with fiberglass cloth saturated in resin. After the resin cures, the fiberglass forms a hard, water-resistant shell around the foam core. This construction combines low weight with enough stiffness and strength for wave riding.

Traditional polyurethane boards commonly use polyurethane foam with polyester resin, while many epoxy boards use expanded polystyrene foam with epoxy resin. Fiberglass is used in both broad construction families, although the exact cloth weight and resin system can vary.

Fiberglass is not the board’s core: it is the reinforcing outer laminate. This distinction explains why a surfboard can feel light but still have a rigid riding surface. Repairs often involve replacing damaged fiberglass and resin over the exposed foam.