Installing drywall to ceiling

[Troy]

Our new liberty home is placed on a basement with beams removed to allow for drywalled ceilings. The joists run from center to outside walls and along the foundation where the home sets, the first joists are back from the exterior wall about 12". The basement walls have now been framed (2 x 4)to allow for 1/2" drywall on the walls, but I was hoping someone here to tell us if we need some kind of support (1 x 6) on the top plate to hold the edges of the ceiling drywall that runs with the width of the home?
Can we use 1/2" on the ceiling or is 5/8" code?
We understand that the walls will be run on edge and to start butting our first piece against the ceiling to help with sagging.

[Mark Bower]

I would use 5/8" on ceiling so in the future nothing will sag. And then I'd install the ceiling first, then the walls. If your walls come up and butt the ceiling panels, you probably won't need support. In fact, some books say to let the ceiling edges float like that to minimize cracking.

Mark
You gotta see my repair manual!