BWP plywood, MDF or HDF: what to use where

Almost every dispute we see between a homeowner and a contractor traces back to one line on a quote that says 'plywood' without saying which kind. Here is what the terms mean.

The three you will be quoted

• MR-grade plywood ('moisture resistant'): fine for bedroom wardrobes and living room units. Not for anything that gets splashed.
• BWP / BWR 710-grade marine plywood: boiling-water proof, phenolic bonded. This is what belongs in kitchens, bathrooms and utility areas.
• MDF and HDF: engineered fibreboard. Smooth, stable, takes a paint finish beautifully — and swells permanently the moment water reaches the core.

MDF is not a bad material. It is a bad material for a wet area, which is exactly where it is most often used badly.

A simple rule

If a leaking tap could reach it, use BWP marine plywood or WPC. If it is a shutter face that will only ever be wiped, MDF is perfectly reasonable and often the better substrate for a lacquered or PU finish. Ask for the IS 710 stamp on the board itself before installation, not just on the quote.