Climbing wall construction - joists vs. studs

Hi all,

I'm currently trying to design a freestanding climbing wall to fit into my apartment (i.e. a wall that will sit on the floor unanchored) and I'm going to make something similar to this (although beefed up a bit more in terms of the supports, and with a kickboard added):

instructables.com/id/Freest…

Unfortunately, the thing that weirds me out about it is Step 4:

instructables.com/id/Freest…

The plywood panels are supported by horizontal joists instead of vertical studs, which goes against every single climbing wall design I've seen in the past. However, I'm not sure if that's really a necessary feature for a square wall, since there's no compressive load parallel to the wall the way there is in walls that are designed to support a floor or roof.

Is there a real reason that this kind of design would be unsafe? It would make construction easier (no need to lift a whole panel of plywood a few feet in the air, less angled joints, etc), and I could make the plywood flush with the frame (2x6 wood for the frame and 2x4 joists recessed by 3/4"). Any advice on this would be much appreciated.

Cheers,
- Alex

I recently moved and had to come up with a smaller version of the wall I had. I used those exact instructions as a basic format for my training wall. I don't have the upper piece of plywood (ceiling too low), just the two 4X8 sheets with the horizontal joists. The thing is totally solid. I won't lie as I was putting it together (I have almost no construction/engineering experience, just common sense) I thought there would be no way the thing would hold together. Once you get the plywood sheets screwed in tight the whole thing locks together. I added an extra two feet to the base 2X4s to prevent any forward tipping. If you're like me you'll wish you had two sitting side by side though. Happy building!

Thanks guys. My current plans for modifying the design are:

- Add a 14-16" kickboard at the bottom and increase the overhanging grade to 40 degrees
- Use 2x6 for the outer frame and recess the joists by 3/4" so the plywood is flush with the rest of the frame
- Use 4x4 posts (or doubled 2x4s) for the vertical supports
- Add a bit of extra wood at the front to prevent tipping (probably not much, 6-10", the addition of the kickboard and angle change put the centre of mass even further from the fulcrum)
- Possibly fasten the top corner joints by cutting a small notch in the 2x6 frame beam and using a joist support instead of angle joints

Cheers,
Alex