Building a bouldering wall in my garage - some construction advice?

So I'm designing a bouldering wall in my garage. It'll be pretty small and simple for now, more or less just a fixed campus board with a few angles. I've been following this guide: rockandice.com/how-to-climb… which is very clear.

But, there's one issue in my garage that doesn't follow any of the schematics I've seen.

I want to connect my walls to the ceiling rafters in the garage. The rafters are perpendicular to the wall. That in itself is straightforward (and matches all the guides I've seen), but I have an open garage and the rafters are a whole 58" between one another.

I could simply screw the header joist 2x6 for the wall panel across the rafters perpendicularly, but that means the entire wall panel is literally connected to only two rafters. An 8' 2x6 can't even stretch long enough to touch 3 rafters.

If I went with the easy solution of essentially following this image:

https://d1vs4ggwgd7mlq.cloudfront.net/wp-content/uploads/Article-Images/Metolius-How-to-Build-a-Home-Wall/7-8.png

then because I can only access two rafters (in this drawing they look to be around 20" between, not 58" as in my garage), I'd be putting literally the entire weight of the wall panel (other than what's going into the wall studs) on four screws. Since I have 2x6s for this, it could be 6 screws, but still. That seems like a bad idea.

I had a thought to do something similarly to this diagram:

https://d1vs4ggwgd7mlq.cloudfront.net/wp-content/uploads/Article-Images/Metolius-How-to-Build-a-Home-Wall/9.png

and basically do a double layer of sleepers – 3 sleepers perpendicular to the wall panel that are attached to the rafters, then 3 more perpendicular to that attached to those, then finally the header joist across those 3. That seems kind of insane honestly, but I'm at a loss at what else to do.

Seems like this is something people have already solved before. You have any ideas?

Pics? If I’m imagining it right I believe you are talking about ceiling joists and not rafters, and that they are there mostly there to keep the rafters from spreading, not to carry a load. How wide is the garage? Are you building in the corner? Are the rafters exposed (the angled boards holding the actual roof?)

Don't cheap out on wood, be prepared to buy a ton of it too. My advice would be to make it free-standing on it's own frame (self-supporting). Think of it almost like a self-sustaining box, though there are obviously many ways, it depends on what you want and what tools you have.

MP Woodies
^^ has many examples for a starting place

It’s hard to imagine without pics of what your particular situation is, however, I’m running into a similar issue I think, of having rafters running random directions with no rhyme or reason to their location...they are all sporadically crossing each other and just flimsy 2x4’s.

I’m building a wall as well, and my plan is to attach the beams horizontally from the back wall studs (behind the climbing wall) to the apex corner of the climbing wall, via joists or bolts. Picture a classic A-frame climbing wall setup, but with the main support beams attaching horizontally to the wall behind it, instead of vertically to the ground, if that makes sense. 

Provide pics if you can

I'm away from home now but can send photos when I get back in a couple of weeks. I ended up doing the following:

1. Attach to the meager rafters as normally, mostly to support the materials to make it easier to build.
2. Buy a bunch of T braces (two per stud on the back of the wood) an some more wood. These are not the T braces I bought (can't find them exactly), but they should give you an idea. https://www.homedepot.com/p/Hardware-Essentials-3-x-3-in-T-Zinc-Plated-Plate-5-Pack-852197-0/203810665 The ones I got are designed to go *underneath* and *above* the joist as opposed to on the sides. Because the force is going in that direction, I recommend finding those if you can, but the ones I linked should be able to take more than enough force.
3. Use a level to draw a line on your garage wall behind the top of the studs on your climbing wall that is the same height as the top of those studs (in other words, it should be about the height of your climbing wall).
4. Cut a header joist the same width as your climbing wall, and screw it into the wall studs below the line you measured.
5. Measure the distance from the top of your climbing wall studs to the header joist on the garage wall. use your miter or equivalent to cut the ends of some wood at that length and on the same angle as your wall. Cut one per stud in your climbing wall.
6. Screw these into your climbing wall studs at the top, and then use the T braces to screw them into your header joist that you added. I wouldn't toenail this as it will take a lot of force.

You should be good to go. My wall doesn't even creak now, feels super bomber. It almost doubles the amount of work you need to do per section, unfortunately, and puts more force on the same wall studs, but like I said mine has been great for 6 months.

I think Aidian also has a good call which I considered but I didn't want to clutter up my garage floor. It does allow you to create a 90º wall with the support though if that's your flavor.

Yes! Note that my garage is weird and very few rafters, as mentioned above, so you can see the supports I did against the studs. The area behind the wall also doubles as a nice storage space.