I aim to place, unsecured, (though blocked from movement on 3 sides) a piece of sheet/engineered wood on top of the side rails of a single bed frame. The siderails are 2 cm wide and will be acting as if beams supporting a subfloor. The horizontal space between the siderails is approx 92cm and the length is approx 191cm.

My understanding is I will be outwidth the max recommended spar/beam distance for a subfloor where I have seen a rough max of 60cm for a sheet of mdf at 22mm thick.

Can anyone recommend the best type of engineered wood for this please? IE • particle board/chipboard • mdf • plywood (softwood) • plywood (hardwood)

And possibly a thickness though I guess the thickest would be best?

Looks not important, I just want the type of engineered wood that is least likely to warp. Thanks G

  • Is this going to sit inside the rails like a mattress and therefore be exactly 92cm x 191cm? Or is it really on top and if so how much larger than 92 x 191? Commented Aug 16, 2018 at 4:51

1 Answer 1


You will want plywood for the application that you desire. The 92cm (36.22 inches) width demands a thick plywood to prevent flexing and warping. Good quality plywood that is 20mm (0.75 inches) thick should be adequate for that width just a small amount of flex.

As a point of reference in the past I had built a platform bed for a daughter that used a 22mm (0.75 inch) thick fir plywood base that was supported along the two long edges very similar to what you are proposing. That plywood was 99cm (38 inches) wide and it was plenty sturdy enough. As a matter of fact to make that platform bed easier to easier to transport and assemble that base plywood was cut in two separate pieces instead of the full length of the bed frame.

  • Thanks for that Michael. Is it the case that you reckon the plywood can be softwood for this application and there is no issue with it having to be a hardwood?
    – user89970
    Commented Aug 17, 2018 at 8:07
  • @user89970 - I had used fir plywood in the case of the platform bed. I guess you could call that soft wood. I did use a higher quality style plywood that had more layers than the typical construction grade plywood.
    – Michael Karas
    Commented Aug 17, 2018 at 10:16

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.