Legs from 3/4 plywood.. load capacity

Woodworking Asked on January 4, 2022

I am designing a 5’x6.5′ loft bed. 4-5 years down the line, I’d like to be able to remove (or trim) and throw away legs ( and any under-bed furniture) and be able to use it as a regular bed afterwards. This is a DIY project.

This will primarily be used by my 5 year old, but should be capable of handling at least 1 adult’s weight also.

I am looking for help to determine if the legs, as designed, would hold up for the purpose.
If not, what would be possible leg design I could make up with 3/4 inch plywood that can do the job. I prefer to use only one kind of raw-material, because of limited tools I have available.

Design details:

Overall assembly is shown in following images:

full assembly-angle-1


The legs are also supported at bottom as shown in first image.
There will be one desk, one two-seat-bench and one long shelf above these supports. Behind all those furniture, I’ll add additional vertical supports (at least 12 high") to legs, hopefully arresting any racking. Legs will not be bearing weight of any furniture other than bed frame.

Legs assembly and attachment are as shown in following image:

leg assembly

Each leg is L-shaped corner assembly of two pieces 64"x5.5" plywood sheets.

I have sketched up two possible corner joints as shown in second image:
(left) with 6 inch thick laps/fingers joint with a 8mm dowel every 6 inches and
(right) finger joint with 1 inch fingers.

Cleats are glued and screwed to bed-frame. Legs will insert into cleat+frame corners as shown. Legs will be bolted to frame with 8pcs M6 bolts in each corner. Frame will have a D-nut insert for each bolt.

I feel that rest of design would be OK, but I am not able to find any resources on strength of plywood in the configuration as being used in legs. So, not sure if legs would hold up.


  1. Updated full assembly diagrams to show positioning of stairs, and internal structure panels added for arresting racking.


  1. New leg design, made from 4pcs of 3" wide plywood arranged as a hollow square. How would this compare to a solid leg made of 4 pcs of 3" plywood pieces laminated together? I believe hollow tube would be stronger than solid core, if cross-section area is same (can’t recall where I heard that)


One Answer

The square legs would be considerably stronger than just the 2-sided legs, but honestly what is wrong with using 2x4's for the legs? You only have to cut them to length and you can nail 2 together for added strength if you want. On top of that you can cover them up with the plywood if you want to have that look, without all the trouble of putting finger joints in plywood. Now if you're using 1" plywood, maybe, but then the cost would be cheaper at that point to go with 2x4's and cover them with cheaper 1/4" plywood.

unfortunately I don't have numbers to back it up, but plywood legs makes me itch with 'not safe'.

the other issue I see, are not enough triangles to keep things from 'racking', unless you plan to run some lag bolts into the wall on 2 sides.

Answered by bowlturner on January 4, 2022

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