Is blocking required for ceilings?

ChrisJJ

Hi,
We're slowly upgrading our garage to make it usable all year around. To keep costs under control, we're doing some work ourselves and hiring others to do the more tricky jobs.

The garage is attached (house & garage built in 1967) and is 25' x 25'. The rafters are 24" on center. There is already fire rated drywall installed between garage and house.

It's now time to drywall the ceiling and we're definitely having that job done by someone else. I know blocking needs to be added along the gable end to give the drywall something to hold onto.

My question has to do with blocking elsewhere. One guy said we needed blocking added, spaced out between all the rafters at every 2'. As a result each sheet will have wood along all edges. Another guy said new blocking wasn't needed other than the gable end.

Now I'm confused. A quick google search gave me images & videos of drywall sheets being attached to rafters with blocking and without. Thinking about it, I can see that the extra blocking between rafters would give more possible attachment points for the drywall and that one could use thinner drywall without sagging. But on the other hand, adding all that blocking adds another layer of effort and cost and I'm wondering if it's overkill.

I looked at the NY state building code and the section on ceiling finishes sent me to the section on wall finishes and that did not say anything about blocking. So it seems that blocking isn't required but I'd admit that I could have missed some bit of info on this.

BigJim

My crews and myself built many houses and never put extra blocking for sheet rock. We always installed sheet rock nailers along all walls where needed. With nailers between the rafters it would be tough on the insulators.

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Jim

racebum

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.

bjbatlanta

5/8" drywall is acceptable on 24" centers without any additional blocking. 1/2" is not unless it's the special "no sag". Regular blocking between the joists should already be in place as required by code to keep the joists from moving/twisting. It is not necessary to fasten the edge of the drywall to anything other than the joist.

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