I'm trying to build a bed frame similar to the one shown below.

I'm struggling to design the long, chunky white support beneath the top bunk.

It looks like its about 200cm x 18cm x 8cm.

For such a long structure, I've thought about using two softwood CLS beams glued together with MDF boxing, but this seems fiddly and I wonder how strong it would be with a child jumping on top of it. I imagine CLS beams flex quite a bit and any mdf boxing around it may crack as a result or the glue may break.

Then I thought about maybe using 3 layers of 25cm birch plywood glued together vertically to create a single smooth beam which can easily be routed on the corners and painted easily without the need for boxing. Although this much plywood sounds a bit heavy, but think it would be very strong for the weight in the vertical axis at least. It would be supported horizontally to the wall, so I'm not as worried about horizontal or sidewise movement.

I couldn't find many examples of creating un-supported boxing like this on the internet.

Does anymore know of a better/best way to create long but strong structures like this?

I'm just interested in the long horizontal beam and not about connecting it to the other bits at the moment.



  • 1
    Make a hollow box section - gives similar strength without the mass.
    – Solar Mike
    Apr 7, 2020 at 10:59
  • I would create a skeleton strong enough for your purpose and assume the which is cosmetic. You could even make a truss for the long parts and then cover it with whatever looks good.
    – Duston
    Apr 7, 2020 at 14:00
  • @duston a truss like diagonals in the interior of the box? Apr 7, 2020 at 19:26
  • @SolarMike but I'm wondering what to build the box from? my worry is that as the skeleton flexes the boxing will crack along the joins, as it will be painted white. Apr 7, 2020 at 19:28
  • What is a CLS beam? Apr 8, 2020 at 14:35

3 Answers 3


There is not a convincing reason this has to be any sort of box structure. In fact for a bed support like that a single USA type of 2x8 (actual 1.5"by 7.5" 38mm by 190mm) on edge on each side of the bed would be way more than enough support. The overall weight can also be accommodated by using proper means to join the ends to the vertical posts.

If you like the wider top surface of the beam next to the side of the bed then that could be easily attained by using two of the typical 2x8s side by side or spread them a small amount and then cap the top and bottom with thin plywood. MDF would work for the cap too but is going to be more susceptible to damage over time if it gets wet.

  • Thanks! Yes, most bunk beds have fairly deep but narrow wood bars, but its the width that is confusing me. I agree two 2x8 side-by-side would probably the simplest, but they tend to be softer wood and wonder how easy it will be to get the joins and edges smooth and painted...? In the UK, we have CLS which is planed but maybe I need the sawn pieces instead. Apr 7, 2020 at 19:32
  • The boxing with plywood or mdf is possible but feels problematic to my, as the inner skeleton bends or even warps potentially. I was thinking birch plywood over standard softwood beams...I think birch plywood is strong and harder wearing, especially if painted...and with kids :) What do you think to plywood instead? Apr 7, 2020 at 19:34
  • I would always go for plywood over MDF, chip board, particle board or OSB.
    – Michael Karas
    Apr 8, 2020 at 1:01
  • I've been doing some drywalling and jointing recently and made me think I could cover the 2x8 beams in drywall and plaster up the joints nicely. Wonder how hard wearing it would be...can't find many examples of this on the internet, but wonder if the picture I originally posted, is actually plasterboards...but can't tell...? Jun 7, 2020 at 21:11

That is a relatively short span and a 2x6 as a beam would support the weight of the bed and things on it (people, etc). The weak point is the connections, use joist hangers at the end for the connection to the post and wall. Then cover with dry wall to make it look nice.

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  • That's a good point. I was going to use glue and long screws and fill their ends and paint over. I guess these would be visible and would require boxing around. But the strength of the joint is a good point. I was tempted to use birch plywood and make a basic dovetail joint at each corner Apr 8, 2020 at 8:07
  • I like the support idea. I'm thinking to use drywall. Do you think drywall will withstand knocks from kids ok? Jun 8, 2020 at 22:42
  • 1
    'regular' dry wall (1/2") will probably get dinged by kids over time. You might consider 5/8" which they use for commercial walls, it's a bit tougher against dings and probably won't break which can happened with 1/2" (kids....)
    – Ack
    Jun 9, 2020 at 4:08

There is different ways to do this but you could create 3 ledgers going around and lag bolt the front in. You can hide the lag bolts pretty easy.

I have done similar type of bunk beds in my beach rentals. I used pine LVLs (both 2x8 and 2x10s) and bolted the front in. Mine were similar with a front ladder, not side. The pine LVLS paint really nice so it gives it that custom look without having to put a ton of work on refacing it. Yea they might cost a little more but maybe like $50 more for the whole bed and they will never have an issue and look great.

I would not use any MDF in your design period... Maybe plywood under the top slats to give a nice flat surface for the top of the bottom bunk. But that should be eat. These are things easily damaged and I would assume bunkbeds are going to hold kids or rowdy adults.

  • Thanks, that's great. May I ask why you dont recommend MDF? Does it damage easily? Apr 8, 2020 at 8:06

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