Thickness & Size · Application Guide
25mm Board Guide: Why 25mm Means Blockboard, Not Plywood
Plywood is made up to 18mm. When a job needs a 25mm board, for long shelves, heavy table tops, stair treads or tall doors, the answer is 25mm blockboard: a solid wood-strip core that stays straight over long spans.
Four Jobs That Call for a 25mm Board
In each case, use 25mm blockboard. Plywood is not made in 25mm.
Long, Loaded Shelves
Bookshelves, pantry and store-room shelves that span 5 to 6 feet between supports without sagging. See blockboard for shelves.
Heavy Table Tops & Counters
Conference tables, large dining tables, study tables without middle legs and shop counters that carry real weight.
Doors & Partitions
Tall door shutters and partition panels that must stay perfectly flat. See blockboard doors.
Stair Treads & Bed Bases
Heavy-duty stair treads and king-size bed bases, in BWP blockboard where moisture is a risk. See stair treads.
| 25mm option | Best for |
|---|---|
| 25mm MR pine blockboard | Dry rooms: shelves, tables, beds and wardrobes |
| 25mm MR double core blockboard | Extra stiffness for the longest spans and heavy tops |
| 25mm BWP pine blockboard | Kitchens, bathrooms, ground floors, stair treads and gates |
| Two 18mm plywood sheets glued together | When you want a solid plywood edge at about 36mm, such as a thick countertop |
Rates for every size: blockboard price list.
Is 18mm Plywood Enough?
For most home furniture, yes. Wardrobe carcasses, kitchen cabinets, beds and TV units are built in 18mm plywood, with supports every 2 to 3 feet on shelves. Move to 25mm blockboard only when a part spans a long distance with no support, carries a heavy load, or must stay perfectly flat over a large panel. See our plywood thickness for furniture guide and blockboard vs plywood.
For a flat painted or CNC panel rather than a load-bearing part, 25mm MDF is another option: 25mm Greenply Interior MDF and 25mm Greenply HDMR MDF.
More Buying Guides
Frequently Asked Questions
Is plywood available in 25mm?
No. Standard plywood is made up to 18mm. For a 25mm board, use 25mm blockboard, available in MR pine, MR double core and BWP pine.
Is a 25mm board necessary for furniture?
Only for parts under real span or load stress, such as long shelves, large table tops, heavy stair treads or tall doors. Most furniture is built in 18mm plywood.
Which 25mm blockboard should I buy?
25mm MR pine blockboard for dry rooms, 25mm MR double core for the longest spans and heaviest tops, and 25mm BWP blockboard for kitchens, bathrooms, ground floors and outdoors.
Can I use two 18mm plywood sheets instead of 25mm?
Yes. Gluing two 18mm sheets gives a very stiff board of about 36mm with a solid plywood edge, which suits thick countertops and heavy shelves.
How heavy is a 25mm blockboard sheet?
An 8x4 ft sheet of 25mm pine blockboard is usually lighter than an equally thick plywood board, because its core is softwood strips, which makes long shutters easier on hinges.
Need the Right Board for Your Project?
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