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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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desk

brhans
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physicsboy
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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 Oct 24 '22 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 Oct 24 '22 at 18:58
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    glued with wood glue they will be more rigid than screwed, it could be up-to twice as stiff. – Jasen Oct 25 '22 at 04:00

1 Answers1

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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.

KMJ
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  • 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 Oct 24 '22 at 19:06
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    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 Oct 24 '22 at 20:05
  • Y posts are cheap but you'd need to drill the flanges to be able to screw it in. – Jasen Oct 25 '22 at 03:53
  • 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 Oct 25 '22 at 17:59