The three plywood grades
| Grade | Standard | What it handles | Where to use it |
|---|---|---|---|
| BWP (boiling water proof) | IS 710 marine | Prolonged moisture and steam | Kitchens, bathroom vanities, sink units |
| BWR (boiling water resistant) | IS 303 BWR | Occasional moisture | Wardrobes, TV units, study tables |
| MR (moisture resistant) | IS 303 MR | Dry indoor use only | Shelves and panels far from water, low-budget furniture |
The names are confusing because "resistant" sounds strong. In practice, MR grade is commercial plywood for dry areas, and it should never be used in a kitchen in Mumbai. Steam from cooking reaches the cabinet carcass every day, and MR board swells at the edges within a few monsoons.
What we specify
For modular kitchens we use 18 mm BWP plywood to IS 710 for the carcass, with the sink unit and the area around the hob always in BWP. For wardrobes and TV units, BWR is generally enough, but a wardrobe on a wall shared with a bathroom should be BWP, because damp travels through masonry. Our kitchen cost guide shows how grade affects price.
Thickness
- 18 to 19 mm: carcass sides, shelves and shutters.
- 12 mm: drawer sides and some internal partitions.
- 6 to 8 mm: back panels.
A cheaper quote often uses 16 mm instead of 18 mm on the carcass, or an MR back panel. Both are hard to spot after installation, so ask for thickness and grade to be written into the quotation.
MDF and HDHMR: when they are fine
MDF (medium density fibreboard) machines cleanly and takes paint and CNC patterns well, which is why it is used for jaali panels and painted shutters. It does not hold screws as well as plywood and swells badly if water gets in. Keep it away from wet areas.
HDHMR (high density high moisture resistant board) is denser and handles moisture better than MDF. It is a reasonable choice for shutters and some kitchen carcasses, and it is more stable than plywood against warping on tall shutters. It is heavier, and screw-holding depends on using the right fixings.
Particle board is used in ready-made furniture. It is the cheapest and the least durable in humidity. We do not use it for built-in work.
How to check what you are getting
- Look for the IS mark and the grade printed on each sheet, along with the brand and batch.
- Ask to see sheets on site before carpentry starts.
- Check that every exposed edge is edge-banded. An open edge lets moisture in, whatever the grade.
- Make sure hardware is named too: hinges and channels matter as much as the board.