WPC and PVC Board for Wet Area Joinery

What it is

Two related board types used where water rules out plywood:

• WPC — wood-plastic composite, wood flour in a polymer matrix
• PVC foam board — rigid closed-cell PVC with no wood content

Both are fully waterproof through their thickness.

Specification at a glance

Where it belongs

Washroom vanity carcasses and cubicle framing · pantry base units, especially under sinks · service duct access doors · utility and housekeeping storage · skirting and architraves in wet zones · locations where termite risk rules out timber.

Where plywood remains better

Long shelf spans under load · structural joinery carcasses · anywhere screw pull-out strength matters · dry office joinery generally, where plywood is stronger, stiffer and cheaper for the same performance.

Where projects go wrong

• Density unspecified, so a low grade arrives and shelves sag.
• Detailed like plywood, with the same spans and standard screws.
• Long runs fixed rigidly, then buckling with temperature.
• Fire class ignored where surface spread of flame is regulated.
• Used everywhere on cost grounds, producing weak joinery in dry areas that plywood would have served better.

Standards referenced

Plywood comparison baseline under IS 303. Composite board testing practice per ASTM D6662. Reaction-to-fire classification to EN 13501-1.