wall and floor fixing am I the only one ????????????

[Jonathan]

Is there room in the design for two diagonal stretchers from corner to corner ?

I think so...

It's common to fix them to the floor, but not the wall. I think it's a good idea to fix it to the wall too so long as you can do it without distorting the frame. The wall is obviously very strong so if the frame is fixed to the 2 walls at a few points you've immediately made it significantly stronger, in addition to stopping it moving.