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My cupboard height is going to be 8 feet and I bought plywood and I didn't realise plywood could bend if the cupboard height is going to be more than 4 feet.

Any suggestions and ideas I should keep in mind while building the cupboard. I can't give back the plywood and get block board.

The cupboard is 10 feet(width),8 feet(height) and 2 feet(depth). I'm worried that the door of this 8 feet high cupboard might bend over the time.

My plywood is 19mm in thickness

Please find the sketches below

Cupboard or Wardrobe Cupboard or Wardrobe

Show case Show case

TV Stand TV Stand

Modular Kitchen

East side wall

South side wall

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    Welcome to Home Improvement. We're going to need a lot more detail. How thick is the plywood? How about a sketch of the cupboard you're building? What kind of corner joints are you making? Honestly, unless you're using 1/8" (~3mm) ply, there's very little likelihood of it bending once you've got it built into a box - even 1/4" (~6mm) won't "bend" once you've built it into a box shape. It might not be quite as sturdy as you'd like, but bending isn't likely.
    – FreeMan
    Commented Nov 18, 2021 at 23:25
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    Yes, please add more details and pictures/sketches of your project.
    – gnicko
    Commented Nov 19, 2021 at 1:14
  • I have added more info along with sketches
    – Amogam
    Commented Nov 19, 2021 at 20:06

2 Answers 2

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18mm plywood (~3/4" for those using imperial units) is plenty thick for a cabinet door, even if it's 8' tall.

Because plywood is made up of plys of wood laid down in alternating directions, it is much more stable than solid wood would be and is much less likely to warp over time than solid wood.

I would recommend that you get high quality "cabinet grade" plywood for this project. Standard building plywood in 3/4" thickness is usually made of 5 plys, while cabinet grade is usually 11-13 plys. More plys will give you more resistance to warping. Additionally cabinet grade plywood is made from higher quality wood with fewer voids (holes in the plys) and those that are there are filled with a tan colored epoxy so they don't leave holes in edges should you happen to cut into one.

Cabinet grade plywood will also come with some sort of nicer wood on the surface plys. You can get Baltic birch, Oak, mahogany, maple and other woods on the surface of the plywood, while the inner plys are made of a cheaper (but still limited voids) wood.

Note that any 2.5' by 8' door of any construction can warp over time. There are things one can do to minimize it, and using 18mm plywood is one of those that will help minimize warping. Don't hang heavy suit bags from the outer edge of the closet door while you're packing, don't let kids hang on the doors, keep a reasonably stable humidity, don't splash drinks on it, are all things within your control that will help. However, wood is a natural product and warping can happen. It's highly unlikely, IMHO, that your doors will warp significantly any time soon.

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    More hinges and magnetic catches will help keep it straight.
    – Platinum Goose
    Commented Jul 13, 2022 at 13:36
  • Thanks for pointing out Cabinet grade plywood , it makes sense to have more plys
    – Amogam
    Commented Jul 13, 2022 at 20:04
  • 4 Hinges and 2 magnetic catch for single door of 8 by 1.5 feet door ? would it be enough
    – Amogam
    Commented Jul 13, 2022 at 20:05
  • I have some IKEA cabinets that are 8' tall. They have 4 hinges (not spaced evenly for whatever reason - I'd space them evenly if I were building my own). They don't have magnetic catches at all. 2 of the 4 hinges are soft close, which sort of "latch" in the shut position. You can use soft-close hinges and/or latches of whatever sort you want. One latch near the top & one near the bottom should help (by holding the door evenly closed), but I don't know that they're necessary. If things really tend to warp that much were you live, they might be a prudent precaution.
    – FreeMan
    Commented Jul 14, 2022 at 14:26
  • Comment correction, @Amogam: My tall cabinets don't have any latches at all, magnetic or otherwise. Thinking this through a little more, if you go with 2 latches and space them too far apart, you may cause bending in the door by pulling the centered handle against the catches that are "far" away from it, warping the door each time you pull it open, instead of just letting it open by itself with zero resistance. I'd suggest that a couple of soft-close hinges will do more than enough to hold the doors closed.
    – FreeMan
    Commented Jul 14, 2022 at 14:40
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Go with 18 or 19mm plywood for door and load bearing areas.

If it's gonna carry less load then you might choose 12mm plywood as well.

Go with 8 or 9mm plywood on the wall side.

Make sure that you are letting the plywood lay idle for 2 or 3 days where it's gonna be fitted so it can suit better for the environment.

Hope this is helpful.

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  • Thanks for mentioning the plywood sizes but still haven't answered what extra steps you can do to stop it from bending
    – Amogam
    Commented Jul 13, 2022 at 9:32
  • Just you have to buy quality product and don't go for longer doors or shelf. Cut the plywood and see if it has any gape between plys of the plywood or any overlapped ply. Take a professional while buying the plywood and he see the edges of plywood and see if it's of finer quality
    – D C T
    Commented Jul 13, 2022 at 9:36
  • My suggestion is to buy a readymade plywood door instead of doing it on your own with carpenters because you can get rounded edges from the factories ..carpenters will usually use Edge tape and the edges will be sharp besides door that comes from factory would have gone through rigorous stress testing and you can be rest assured.
    – D C T
    Commented Jul 13, 2022 at 9:39
  • thanks for the suggestions
    – Amogam
    Commented Jul 13, 2022 at 9:45

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