When hanging drywall the ceiling is the most difficult as you are holding up a large sheet while trying to get a few screws started in it. By installing the ceiling sheets first this gives you a little tolerance in cutting and aligning the sheets because you have 1/2" to play with at all edges because the sidewalls will cover up to 1/2".
If you hang the walls first - you would need to measure and cut the ceiling panels to exact measurements - I mean exact.
Plus standard framing using pre-cut 8' and 9' studs gives you a small space at the bottom of the drywall after hanging. If you increased that by 5/8" (most hangers install 5/8" drywall on the ceiling), you would have a large space or void at the bottom of the wall.
Hang the ceiling first - you will be glad you did.
Start by snapping a chalk-line by measuring and marking out from the corners 48+3/8". This chalk-line is where the edge of your first ceiling sheet should line up. Stay on this chalk-line. Always put your cut ends to the walls and your factory or uncut ends together and breaking on the center of a ceiling joist.
Stagger the next sheet about 4' from the previous joint. On new construction with an attic above, do not screw the drywall within 6" of the wall on sides of the sheets. This is because roof trusses dry-out in winter and create tension on the bottom chord or ceiling joist and this causes drywall ceiling/wall joints to crack.
Hang wall sheets horizontal, again with all cut ends to the wall and factory edges (uncut) against each other. Stagger joints and cut full pcs over doors and windows so that the edge of a sheet is not right on the edge or side of a window.
Measure for drywall prior to ordering as sometimes different lengths work better according to the room measurements. Try to use full pcs. on rooms under 12', and do not use pcs. smaller than 16".
Use 1+5/8" screws for 5/8" thick drywall and 1+1/4" screws for 1/2". These are coarse thread drywall screws for wood framing.
Always mark joist and stud locations on the drywall prior to hanging. This saves time and keeps you from missing the joist or studs. Measure from the wall to the center of each joist or stud and then transfer those measurements to the sheet of drywall.
Use a drywall screwgun or a cordless drill with a simple drywall dimpler attachment. The screw should end up slightly below the surface of the paper cover on the drywall - sort of dimpled. If the paper tears, then the screw won't hold.
Get all set up before you start. Get a tool pouch to put your screws in, a place to keep your tape measure, pencil,chalkline,hammer holder,screw gun holster,drywall square,drywall rasp *(used to rasp down jagged cuts on drywall sides or ends, a good utility knife,extra utility knife blades, extra phillips screw tips for screwgun and or dimpler attachment for cordless drill.
Do not attempt to finish (spackle & sand) the drywall yourself - please !! This is not as easy as it sounds. And don't leave wide or open gaps in joints thinking the drywall finisher can fix it. Do a good job hanging the drywall, even if it takes longer.
General Contractor 30yrs. and counting