Re: need to lower ceiling in bathroom
It's easily done but quite frankly seems like extra work. It's just as easy to leave the dimensions as is.
For a 9 ft wall you can easily use 4x8 drywall by hanging them horizontal --- at the seam install a 1 foot strip --- hang the next sheet horizontal --- you have your 9 feet.
Because the seam would be taped and mudded anyway having the 1 foot strip in this location will blend in better.
Otherwise if you feel you need to drop the ceiling ........
measure down from the ceiling ---- fasten a 2x4 all around the perimeter to the wall studs ---- cut your new joists to fit and fasten in place evenly spaced.
"" an ounce of perception -- a pound of obscure "