Plywood Grades Explained: MR vs BWR vs BWP (Marine) for Kitchens, Wardrobes and Furniture

Why plywood grades matter

Plywood is made by gluing thin sheets of wood (veneers) on top of each other with the grain of each layer at right angles to the one below. That cross-lamination is what makes it stable and strong in both directions. For a refresher on how it compares with solid wood and MDF, see solid wood vs plywood vs MDF.

What separates one grade from another is mainly the glue and, at the top end, the quality of the veneers and core. The glue decides whether the layers stay together when the board gets wet. That is why the grade you choose should follow where the furniture will live.

The grades

MR grade is interior plywood. Its urea-formaldehyde glue copes with normal indoor humidity but weakens if it stays wet, so layers can separate (delaminate) under a leaking sink.

BWR grade uses phenolic glue, which is far more water resistant. It is the sensible default for most kitchen cabinets and for furniture in humid coastal cities.

BWP grade, commonly sold as marine plywood under IS 710, is the top of the range. It uses waterproof phenolic glue and also has stricter requirements on veneer quality, gaps and overlaps in the core. It is the safest choice for anything near constant water.

Grade names on invoices are sometimes used loosely, so check the standard printed on the sheet.

What the grade does not tell you

The core species

The inner veneers can be cut from different timbers:

• Gurjan and other dense tropical hardwoods give a heavier, stronger board that holds screws and hinges well and copes better with moisture. Marine plywood traditionally uses gurjan.
• Mixed hardwoods are common in mid-range boards.
• Poplar and eucalyptus cores are lighter and more economical. They are fine for many interior uses but hold screws less firmly and are less tolerant of water.

Thickness and construction

• 18–19 mm is standard for cabinet carcasses, shelves and shutters.
• 12 mm suits drawer sides and partitions.
• 6–9 mm is used for backs and drawer bottoms.
• Calibrated plywood is sanded to an even thickness, which makes for tighter joints and flatter shutters.

Treatment

Many manufacturers treat veneers against borers and termites. That is separate from the glue grade and worth asking about (see protecting furniture from termites).

Emissions

Formaldehyde-based glues release small amounts of formaldehyde. Many brands now publish emission classes such as E1 or E0 (lower is better). If indoor air quality matters to you, ask for low-emission boards, especially for bedrooms and children's rooms.

Which grade where

Edges are where plywood fails

Water rarely gets in through a laminated face. It gets in through cut edges, screw holes and joints. So:

1. Seal every exposed edge with edge banding or laminate.
2. Use a liner laminate on the inside faces of kitchen cabinets.
3. Keep a gap, or use a waterproof plinth, at floor level where water is mopped.
4. Fix leaks quickly: even marine plywood will swell if it sits in water.

The finish on top matters too; see laminate vs veneer vs PU vs duco.

How to check what you are buying

• Look for the ISI mark with the standard (IS 303 or IS 710) and the grade printed on the sheet.
• Check the thickness with a measuring tape or calipers at several points.
• Look at the edge: layers should be continuous, without large gaps or overlapping veneers.
• Ask for the core species and any borer/termite treatment.
• Make sure the grade on the sheet matches the grade in your quote and bill of quantities. Our guide to what a turnkey interior project includes explains how to read a BOQ.

How we specify plywood at Savistar

Board grade is one of the first lines we specify in any interior project, room by room, because a wardrobe and a sink unit need very different boards. If you are planning a kitchen, see our guide to modular kitchen layouts, or talk to us about your home.