I currently have a 2.2m desk made from a double layer of 18mm birch plywood - So 36mm in total - That is currently supported by 4 hairpin legs (700mm tall), one on each corner and a set of drawers (700mm tall) for support in the middle.

My plan is to mount this desk on the wall with battens.

I have done a test fit and it seems that my main fear is becoming a reality, and the table is sagging somewhat on the one side not supported by a batten.

How can I go about making an addition to strengthen the unsupported side such that it doesn't sag/bow?

My initial idea was a metal support - C channel or box section

Photos (Click to enlarge)

Note: Spirit level is 1.8m long

Mounted front of desk (away from wall)

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Mounted Back of desk (At wall)

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Before mounting - note: middle is being supported by drawers

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  • Are those two plywood sheets just laid on each other or glued together? If they are properly glued it will reduce any bending.
    – Solar Mike
    Commented Oct 24, 2022 at 18:36
  • @SolarMike They are screwed together around the periphery. I originally planned to glue them together but was renting at the time and didn't glue for portability.
    – physicsboy
    Commented Oct 24, 2022 at 18:58
  • 1
    glued with wood glue they will be more rigid than screwed, it could be up-to twice as stiff.
    – Jasen
    Commented Oct 25, 2022 at 4:00

1 Answer 1


You can use a stiffener, something like this. If you want to build it out of wood, a 100mm or so ripped piece the full width can go under the middle at 90 degrees to the underside of the table. Screw and glue it to the underside with a temporary support in place. Basically what you're doing is adding something that provides support in the direction that your plywood is weak.

  • Could C-chanel work the same way? Thinking about catching my knees on the protrusion of the product you showed. Or even a right angle piece of steel inserted in a V orientation with the point of the v downwards
    – physicsboy
    Commented Oct 24, 2022 at 19:06
  • 2
    Sure. Angle iron could work, C profile could work, Unistrut could work. It's all about getting the forces so that they're trying to do something tough (stretch steel or stretch a board) instead of something relatively easy (bend plywood).
    – KMJ
    Commented Oct 24, 2022 at 20:05
  • Y posts are cheap but you'd need to drill the flanges to be able to screw it in.
    – Jasen
    Commented Oct 25, 2022 at 3:53
  • Most kitchen tables have a skirt or stretcher board around the edges. It not only looks nice, but it gives more strength to the leg attachments, and it prevents the top from sagging. If your desk is so low that you'd hit your knees on a 2-4" (50-100mm) piece underneath, then you might want longer legs under the desk!
    – FreeMan
    Commented Oct 25, 2022 at 17:59

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