I'm building my son a loft bed. I'm trying to make it really sturdy because he has a tendency to break things. Each leg will be two 2x6s (brown in picture) joined with pocket holes. In the inside corner of each of those legs will be a 4x4 (red in picture) that extends up under the mattress. The 4x4s will support horizontal 2x6s (orange in picture) which will brace the slats (not pictured) for the mattress. All the way around the mattress will be three rows of 2x4s. These are green in the picture but I did not picture them going all the way around. There are two additional horizontal supports at the bottom (also green in picture) going around the back and both sides but not the front. The blue ladder on the right side will be made from 2x4s. This bed is meant to support a rambunctious 10yo boy as he grows into adulthood. I know diagonal supports do make structures more sturdy but is it necessary considering the 5 horizontal and the leg design with three boards? enter image description here

  • Should work... be sure to use at least 2 screws per end of each 2x4. If it racks after you've built it, you can always add a bit of plywood (like, 12" tall) on 3 sides at the bottom. Aug 14, 2022 at 18:55
  • 1
    Two big bolts into the wall [3 if it's in a corner] would obviate a lot of your extra support requirement.
    – Tetsujin
    Aug 15, 2022 at 10:49
  • 2
    This is significantly over built compared to the bunk beds my two boys slept in for more than a decade. It was made by my FIL out of a single 2x4 post in each corner and 1x4 horizontals with 2 end slats for each bed section (very rigid across the short dimension) and nothing but the mattress support rails held in by bed support hardware for the long direction (with some wobble). My eldest was also rather destructive and didn't make a dent in this structure. As designed, this thing will take a small aircraft crash landing on it.
    – FreeMan
    Aug 15, 2022 at 14:32
  • I got plans here. oploftbed.com
    – Xavier J
    Aug 16, 2022 at 16:09

4 Answers 4


I'm posting this as an answer because I know I will exceed the limit for a comment. I've built about 3 dozen bunk beds for a church retreat facility. They were all red oak. The side rails and the headboard/footboard rails where all mortise and tenon...that about the strongest joint out there. But unless you have a well equipped shop, not a DYI project. That said....

If you could put a shallow dado in the legs where the rollover rails go (the green boards) wide enough for the rollover rails, making it a snug fit, then fasten with bolts. That would go a long way to minimize racking rather than counting on the fasteners alone to prevent it. For appearance sake, you'll want to do that on the inside of the legs.

For the mattress surface, I used plywood screwed to cleats on the headboard/foot board rails as well as the side rails. That really ties things together and makes it very sturdy.

You are planning a purely vertical ladder. I have found those are hard to climb and if you could incline it by about 10 -15 degrees it makes it a lot easier to climb. You could do that by cutting a long wedge attached to the legs. On my ladders, I cut dados to accept the steps and screwed them in from the other side of the wedge. That way, the weight is supported by the dado in the wedge rather than the fasteners. Alternatively, you could build a detachable ladder. I'm attaching a pic of the finished product. (OK, maybe bragging a bit!, sorry), but I think it's a good simple design that maybe might give you some ideas.

Lastly, don't forget you need a rollover rail along both the long sides of the mattress.

bunk bed

  • 3
    Do you mean "groove" (a narrow channel or depression) rather than "grove" (a group of trees)?
    – psmears
    Aug 15, 2022 at 11:10
  • 1
    LOL @psmears. Excellent point. ;)
    – FreeMan
    Aug 15, 2022 at 12:47
  • @psmears I probably should have used the term "dado" but not everyone knows what that means, so I called it a groove. Funny comment! Thanks! LOL Aug 15, 2022 at 13:40
  • @psmears I also noticed I misspelled groove! I'm going to edit my answer and change it to dado. Aug 15, 2022 at 13:54

Did something similar once.

Legs were four 2x4 and rails 2x8, cross pieces 2x6 and cutouts in the legs (1” deep) so that the wood supported the rails just held secure by bolts.

Used by 2 adults for “normal” night-time activities…

No racking as the legs were against the walls - it was a small room with a high ceiling.

  • 6
    Used by 2 adults for “normal” night-time activities… If Solar Mike is under 40, this means that the bed is robust. If Solar Mike is over 50, this means that the bed was not tested under duress.
    – dotancohen
    Aug 15, 2022 at 10:45
  • @dotancohen under 40 when I built it, but also over 100kg at the time…
    – Solar Mike
    Aug 15, 2022 at 10:58

Firstly, that thing is a beast and will probably last decades as-is. It's probably going to weigh over 100 pounds.

My one suggestion would most certainly be to add some shear strength via cabinet-grade plywood; 3/4" sande plywood.

This serves two purposes:

  1. Shear strength; virtually eliminate any lateral movement
  2. Utility: decoration, mounting things, kick board, etc...

With the plywood you could also scale back your use of 2x6 + 4x4 posts. You'll achieve massive amounts of rigidity with the plywood.

enter image description here

Note: there is no plywood on the right side behind the climbing rails; I merely botched your drawing.

Also, I would plan for an angled ladder with flat steps. The amount of PSI those thin ladder boards will impose will gradually get more uncomfortable as the years go on.


Unfortunately I am not qualified to make comments to your construction, other than to say, it is massive.

Sharing ideas:

Some time ago, I build a bed with very fancy looking legs.

I only used 2x2 for the entire structure.

I paired two 2x2 (becoming 2x4) to increase the horizontal strength to hold the mattress.

Here is a primitive drawing, as I do not have 3D drawing capability.


The red are the verticals and the gray are horizontals at different hight. So you end up with 2x2 legs with 2 inch opening in between (looks fancy).

Then the whole structure was screwed with appropriate length screws and nuts.

One day they grew up, and I just unscrewed the structure in to 2x2 pieces.

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