OK, so I’ve just read the ‘Hanging Drywall Overhead’ article and have reread the ‘Perpendicular or parallel?’ paragraph several times… but here’s the thing; I have a combination dining room/living room ceiling that is 12.5 ft by 25 ft with the joists spanning the width which means I could board the ceiling parallel to the joists with 14 ft sheets and wind up with no butt joints. So, the only argument against parallel that concerns me in this case, is the potential for sagging because of the strength difference… Will 1/2″ board sag on 16″ centers if hung parallel? How does drywall wind up being stronger in the long direction? Cheers and thanks in advance!
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Hope everything is square and the joist are arrow straight. Breaking the tapered side on a 1 1/2" joist isn't a bad thing, but it is unusual to find a truly square corner to start in. That means tweaking the first sheet by cutting the 4' end, or making a tapered rip the length of the board to true up the rest of the install. Once that first ceiling to wall line board is true, the rest of the board goes in with only cuts on the butt ends. If you are hanging the board for a living, speed becomes a big factor. You learn quickly to trust your own skills, not the framers. A joist that is 3/8" off in either direction will mean a long rip on the tapered joint or scabbing on blocking for the edge to land on. Finisher don't like tapered joint messed with because it then becomes a really long butt joint.
1/2" drywall hung overhead on 16" centers is fine. You should not have any sagging problems.
If you really want to hang across the short run of the room, you might consider strapping the ceiling with 1x material. that effectively changes the direction of the joist. You loose 3/4" in ceilng height, but if there're no other ceilings running into that room, the difference in not noticed.
Dave
Welcome to BT.
I have never seen drywall run parallel to ceiling joists, nor have I seen 14' drywall. Is 14' drywall available where you live? I guess they might have it a speciality store here but I never asked, and almost always by drywall from building supplies.
Run strapping Perp. to joists
hang the sheets the 14foot direction
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Thanks for the insights folks. I can't strap the ceiling because I installed a woodstove chimney when I did the roof and it would be absurd to move it down 3/4" now... My joists are pretty true but this is a very good point - if they run off it will defeat the purpose... After comparing the total combined joint length today, I realized that I would only be adding 12.5 ' of butt joint (with a combo of 12's and 14's - and yes I already have the 14's...) I did another search tonight and came up with some info on drywall "grain" from an old posting (ie; directional strength). So, I guess I'll be normal and hang it perpindicular...
Good.
I think you're better off going perpendicular. I helped my Dad hang drywall parallel to ceiling joists once. (Although it's been quite a while back) After about 5 years it sagged so bad we tore it out and replaced it with drywall running perpendicular.I have no idea why that is - That drywall can be stronger one way than the other. But it sure seems to be the case.
Ambiguous headline: MAN STRUCK BY LIGHTNING FACES BATTERY CHARGE
I would think that one reason it would be stonger perpendicular would be the tapered edge. You have the face paper wrapped around and I think the material is compressed to make the taper, making it more dense/ridgid.
This is just a theory - I don't really know how drywall is made, but I sure think the tapered edge is stronger.
"I have no idea why that is - That drywall can be stronger one way than the other. But it sure seems to be the case."
The Taunton book of DW (Myron Ferguson) discusses this. Evidently DW has grain, and he shows (in a photo) the effect of bending the DW with concrete blocks as weights. Bends much more in one direction than the other. Seems mysterious to me as well, but I will hang perpendicular.
Both 1/2 inch ceiling board and 5/8s fire code is fiberglass stranded for support.
The strands across the width are only four feet of course while the other strands span the lenght of say 12 feet. The process of banding comes to play just like nailing deck boards across joices thus helping hold a straight line. It was decided here a few years ago that blocking didnt help support a floor after the plywood was installed . Another support theory of mine in the stranded drywall is looking at a rope bridge. There are many means of support but only one to keep it there swinging over the water.
Tim
Around here it's always 5/8" board on the lids whether they're 16 or 24 OC.