I have an interior wall in a building with metal roof trusses and drop ceilings. There are no wooden truss members or joists to attach the top plate of the wall. The interior wall will attach to an exterior wall on one end and end in a corner on the other end, but I must build something to attach the top plate to down from the steel roof truss members. Just wondering how often I need to do this. I am guessing 8 feet would be ok?
In my opinion this should be done 3 times per span at a minimum. So really it depends what you are building with. If you use your stock 2x4s that are 8 feet then 3. But If you get longer 2x4s I think you can also go with 3, given there are no breaks.
(This is also assuming that you can fasten the bottom every couple feet)