UKC

Thinking of building a wall in my garage, I was going to do a freestanding one but now thinking of suspending it from joists / roof truss 

The joists are 2x7 inch (17.5cm x 5cm) and each end sits on a concrete block wall.  Would I be able to hang a 40 degree board from these, am thinking 2.4mx 2.4m 18mm ply, and hanging with chains / slings or rope. The bottom edge will be on a hinge from a small kickboard and situated against a wall. 

Are these joists / trusses strong enough, they look pretty meaty to me!

Thanks

Also, 2nd question!

What's the best size timber to use for the framing to mount the ply sheets onto?

What is the span of the 7x2's, and what spacing between? They are generally strong to 3.5m

Whats above?

I would frame the ply with 4x2 at 600mm centres 

Hmm span is 5m, but would be running from L to R side of the board not front to back so I could suspend it from 2 of them or place another timber on top of them at 90 degrees and attach to that to spread the load more? 

Spacing between is 55cm

There's an empty room above so just some laminate flooring, kids just use it as a play room so only a few toys in there

I'd build the diagonal struts off the floor, not a hinge above the kickboard. It'll be easier to build and you can stick a kickboard inboard of that if you want.

4x2 is quite spindly for a 40° structure and it may flex more than you'd like. 4" dressed timber is in reality only 89mm (I think) so I'd bump it up a size from there. 600mm centres is fine as are the existing rafter sizes. Or you could stick with 4x2 main frame supports and put them in at 400mm  centres rather than increasing their section.

Edit: typos.

i’ve just moved, so have built the first of a series of walls in my garage. This one is 20 degrees. The top trimmer is bolted into ceiling joists. The framing timber is 6x1 as it’s really cheap in 3.6m lengths at the local fencing contractors shop. Board is 18mm shuttering ply which was £26 a sheet from  the local Travis Perkins. I did put some bracing in the back about halfway up which supports storage shelf. Centres are 2 foot, with 4 inch edging so that a 8x8 tnut matrix isn’t blocked by any stud work.

Holds from my old wall mostly Hardwood Holds, Beastmaker and Holdz. Next up is a 40 degree board and campus board.

PS your joists are plenty meaty for this.