Is blocking required for ceilings?
depends. it's easier if you cut a few 48" 2x4's when you do the install. i assume you'll use 5/8" 4x12 sheets for the ceiling. when you hang, you cut the board to fall on a joist then attach your 48" 2x4 with 2-3 16d's for the next sheet to start on. doing this will prevent any sag from an end that doesn't get attached to a joist. since a 2x4 is 1.5" wide that means if you're perfect 3/4" of sheetrock will be on it if you split the same way you would if you were doing roof sheathing. easy with plywood, not as much with sheetrock. your whole garage would cost 10 bucks or so in 2x4's, it's actually time saved to be able to just bang and hang
one last thought. in new construction it's often easier to skip this step because things are fairly true. let a house settle for a decade plus especially if it's made with 2x4 truesses and 24" oc you will have some run out and wobble boards that would make you wish you had installed what i just mentioned. i just hung a 1985 ranch house with 2x4 trusses 24"oc, there were a couple spots that started at one measurement and were 1/2" off at the end of 48" due to run out in the truss.
Last edited by racebum; 08-20-2010 at 02:37 PM.