Repairing Sagging Drywall in Ceiling

In the middle of my kitchen reno and while working in my attic, I discovered that 1 or 2 full sheets of drywall in my living room are sagging badly. Apparently the construction adhesive used 30 yrs ago simply dried up and lost its hold. Since they used nails not screws in the 1970s to attach the drywall to the rafters, there wasn't much to keep it up. At the lowest spot, the gap between the drywall and rafter was about 3/4"!! From inside the attic, I could slide 1/2 my hand into the gap! I figured the whole thing would collapse from its own weight any minute. I raced to HD and propped it up with a bunch of 2x4s. My living room looks like a circus tent.
Getting it supported was step 1. I now need to figure out step 2...repair. Replacing all of that ceiling drywall is NOT the preferred option. My attic has about 18" of loose, powdery, blown-in insulation. Moving that stuff around is a nasty job. I don't believe the drywall is cracked anywhere. It simply sagged as a full sheet (or 2 sheets). I'm hoping that getting it flush to the rafters with the 2x4s and then using LOTS of drywall screws will keep it up there for another 20 years. With the loose insulation, getting adhesive in the gap before screwing up will be difficult if not impossible.
Anyone have experience dealing with this problem?
--Jeff
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Your plan is sound. Most ceiling drywall around US is installed without adhesive. The head of the drywall screws will hold the drywall and the threads will hold the screws into the joists. You will want to space the screws 8-10 inches and while you're at it do the whole ceiling, not just the sagging area. The reason its sagging in the middle is the edges are held up by the vertical drywall pieces, so the adhesive used is probably failing everywhere.
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On Wed, 13 Feb 2008 06:33:12 -0800 (PST), snipped-for-privacy@gmail.com wrote:

Lots of screws? Professionally we do only 3 screws in the field of each sheet on each rafter, with 1 nail on each edge of the drywall sheet on each rafter. Nails/Screws go in every 6 inches or so on the butt joints. If the drywall is sagging that much you may also have a moisture problem. I also suspect that the glue is holding, but the drywall gypsum is separating from the paper backing. Glue is unacceptable on the ceiling except to keep it from creaking, not to hold it up.
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snipped-for-privacy@notasarian-host.net (Mike Dobony) says...

12" O/C in the field is OK for screws, but not for nails. If you are using nails, you have to go 7" O/C.
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Yep sure have..First I need to know the thickness of the sagging drywall...If it is 1/2 or 5/8 it MIGHT be savable...3/8 or 1/4 inch...SOL I'm afraid...Sorry....
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You can try to secure it to the studs with screws. If it's 3/8 sheetrock, it might be difficult since it's thin plus it will want to pull away from the rafters. Another option is to laminate over the ceiling with 3/8 sheetrock.
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Do you have some sort of false ceiling? How come this is only noticeable from the top?
First off, check for water damage. That's often a culprit for sagging sheetrock.
Second off, IF you can get it back into place, just screw it in. Don't bother with any glue.
Finally, if it's sagging that much, check around. If it's sagging that much, the slack had to come from somewhere.
Good luck with it.
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This is 1/2" DW. There is no moisture problem and the adhesive failed...not the paper. The backing is intact and the adhesive is brittle and crumble-y. I found the same thing when I removed soffits and installed small pieces of drywall in my kitchen as part of my reno. This is a split foyer house so most of the living space is upstairs. With attics getting to 125F in the summer (even with a gable fan), its no wonder that after 30 years, it just lost its strength.
And as far as warning signs from below, I have to admit that there were some I didn't pay attention to. I thought fresh nail pops were due to vibration from wood floor installation in the kitchen plus me moving around the attic doing electrical work over the kitchen. I kept saying to myself "Its minor and I'll spackle it later". I now see hairline cracks in the crown molding along the wall and tape seams showing where they didn't before as it began to sag. In hindsight, it was getting worse by the day! I think I had somewhere between 2 seconds and 2 weeks before it collapsed under it own weight. It was sheer luck that I noticed it while doing some recessed lighting work in the attic outside the kitchen area. Lucky me and a big lesson learned.
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wrote:

This is 1/2" DW. There is no moisture problem and the adhesive failed...not the paper. The backing is intact and the adhesive is brittle and crumble-y. I found the same thing when I removed soffits and installed small pieces of drywall in my kitchen as part of my reno. This is a split foyer house so most of the living space is upstairs. With attics getting to 125F in the summer (even with a gable fan), its no wonder that after 30 years, it just lost its strength.
And as far as warning signs from below, I have to admit that there were some I didn't pay attention to. I thought fresh nail pops were due to vibration from wood floor installation in the kitchen plus me moving around the attic doing electrical work over the kitchen. I kept saying to myself "Its minor and I'll spackle it later". I now see hairline cracks in the crown molding along the wall and tape seams showing where they didn't before as it began to sag. In hindsight, it was getting worse by the day! I think I had somewhere between 2 seconds and 2 weeks before it collapsed under it own weight. It was sheer luck that I noticed it while doing some recessed lighting work in the attic outside the kitchen area. Lucky me and a big lesson learned.
1/2 inch might be doable..Start in a corner and work it back up using 2X4's like you are for bracing and screw it every 3 or 4 inches with a DRYWALL SCREWGUN using 1" 5/8 drywall screws and make sure the screws aren't set to deep. Take down bracing out in front of you as you move out to prevent buckling of the sheetrock.Leave bracing in place for a day or so where the worst of the sag was.... This might or might not work.It depends on how long it has sagged. If it's been to long you can never seem to get the curve out of it even if you get it back up... Worth a try...Good luck....
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Corner??? I'm thinking starting in the middle and working my way to the outsides. Altho if its jacked up with 2x4s, where I start/finish may not matter.
--Jeff
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On Wed, 13 Feb 2008 12:48:16 -0800 (PST), Jeff B wrote:

Not good. Start at the outside edge of each drywall sheet and work toward the middle. 1 5/8" screws are overkill, but might be needed to grab the rafter. Start along a wall parallel to a rafter and run the entire length of a rafter. Move on to the next rafter and keep moving from one side of the room to the other. If the screws pop through you may need to slowly work each screw up a little at a time to keep them from popping through. Go slowly to keep from popping the screw heads.
The dimple bits work well in a drill for as much as you are doing. If you know someone with a real screwgun that is better, but don't overdrive the screws. They need to be just below the surface of the drywall.
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wrote:

!"1/4 screws are normal for 1/2 inch drywall and I was allowing a little more for the old glue that might hold it away from the rafter a bit and to give a little extra to draw the sheet up. The clutch in a real screwgun makes it ALOT easier. Always could rent one or borrow one.
Jeff, if you start in the middle you are asking for trouble but it's your baby....LOL...
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You are in a tough situation. You have several factors adding up to a practical impossibility.
Newer drywall panels intended for ceiling use are more sag resistant - the stuff made 30 years ago is more prone to sagging without any additional load being placed upon it.
You do have a load - that 18" of blown insulation can easily exceed the sag resistant drywall rating of 1.3 PSF. Blown insulation can vary a great deal, but 1 to 2 PCF is not unusual. The conversion does not work in your favor.
USG specifies ceiling screws to be on 12" centers, and that's with the newer sag resistant stuff. The older spec was screws on 8" centers. Again, that's based on a 1.3 PSF maximum surplus loading.
The insulation that has worked its way between the drywall and the ceiling framing isn't going anywhere without help. Buildings, particularly wood framed buildings, move with changes in temperature and humidity and with loads applied from above, such as your crawling around in the attic. If you screw the panel back up as best you can and there's a gap, more insulation will squeeze its way into the gap as the building moves. This will be slow to happen, but it will happen and it will create a fair amount of force and the screw heads will start to pull through the face paper.
I see zero chance of a long term solution if you don't remove the insulation from the area in which you are working. You could start at one end, push the loose insulation to the far end, vacuum out the crevice under the joist, and then jack up that area and screw the board up tight. Then you'd have to move the insulation back into the area you worked and start on the adjacent section.
In your situation you will definitely want the screws more closely spaced - say 8" centers. Adhesive or expanding foam would help seal the drywall/joist gap and keep more insulation from working its way between the two. I would also consider filling the joist bay with loose fill insulation, then stapling Tyvek on top of the joists so it's fairly taught, then putting the rest of the loose insulation on top of the Tyvek. That would be one way, off the top of my head, of keeping the insulation and taking some of the load off of the drywall ceiling.
Another option - and it's really easy for me to spend your money for you - is to remove all of the loose fill insulation and use spray foam over the entire drywall ceiling. If you put six or more inches in place in place it would bond to the back of the drywall ceiling and to the joists and make the whole system more of a diaphragm/beam.
Basically, this is the situation: rock > you < hard place. Sorry.
R
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Jeff-
Per Rico's comments.......getting the drywall snug back up against with joists with that isulation is going to be very difficult (read: nearly impossible).
If you really want the ceiling to be flat you've got to get that insulation out of the way....even a few stray clumps, chunks, bit will locally prevent the drywall from seating properly & as you drive screws (or ideally as you gently jack it into place) the insulation will compress & the drywall will bulge or crack. :(
Vacuuming all out is doable & you can save it in large trash bags which you could hang from the roof rafters (if you have enough room)
Ideally getting all of the insulation off the drywall is the way to go but if the material handling logistics is too difficult maybe doing 1/2 of the room at a time could work.
Are you going to try & save the joint work?
If so, ideally you need to jack the ceiling up evenly over the entire area, You fashion a could several "strong back frames" to distribute the jacking force to the ceiling. Something like the lift points of a drywall lift. This would minimize the number of jacks you needed.....the load per sheet isn't huge but each sheets needs several jacking points. But this would be a lot of work. :(
Your situation is difficult because of the loose fill insulation & the fact the entire ceiling has sagged.
Jacking up the entire ceiling (or even "strips) is a lot of work but incrementally screwing screws in sounds tedious. :(
Jeff... I think MIke D's comments about starting from the edge & working a "strip" of drywall along a rafter makes sense. I believe his concept is to use the screws to slowly draw the drywall back up against the joists and avoid the jacking setup entirely. If his concept works it would be much less effort than jacking the entire ceiling.
If you try to use screws only (no jacking) space them relatively far apart so you have fewer jacking screws to incrementally screw. :(
When the sheet or ceiling is completely flat, go back a drive intermediate screws home in one shot.
In my town per code, 1/2 drywall ceilings get 1 5/8" screws at 6" o/ c. Which seem rather long and rather close together. What ever spacing you choose, consider making the jacking screw pattern an even multiple of the final screw spacing and an even divisor of the sheet size.
If you had a helper or two you could do the work with a lot less "up & down the ladder".
Or, if you're up to it....drywall stilts
let us know how it all works out
cheers Bob
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There is no need for a very thick coat of mud (there is just as much mud in any given corner or on tapered edges in a standard installation), there is no need to use green board (green board and not blue board?), and the ceiling buttons distribute the stress far better than any single screw head. It's not a question of the screw threads holding in the wood, it's a question of the head pulling through the face paper. Spacing the screws 8" apart instead of 12" doesn't address the screw pulling through the face paper. If you don't want to cover the buttons with mud, then use a small scrap piece of plywood or stiff plastic to act as a button while you screw the drywall in place then remove the scraps and finish off with standard screws.
In either event, the loose fill insulation is a problem. Using screws to compress the insulation that is already between the drywall and the joists and pull the drywall up tight is not a viable solution. You will be able to reattach the drywall using just screws, but it will not be tight to the framing. Having drywall that is not tight to the framing is a sure way to insure that you repair your repair down the road for reasons I mentioned before.
R
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Thanks for all of your suggestions. I've been trying to figure out my battle plan while I stare at a bunch of 2x4 support poles in my living room. Repair will be this weekend's project. I'll be checking up in the attic to see how much (hopefully none!) of the insulation worked its way under the rafters.
I'll report back early next week.
--Jeff
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The repair of my sagging ceiling went well over the weekend. There were 2 connected 4x8 sheets that were the problem. And to make matters more complicated, one of them was over a stairwell. Luckily there was NO insulation under the rafters/joists since the original builder stapled vapor paper (almost like thin package wrapping paper) to the joist channels. This kept the insulation between the joists.
In addition to the 5 or 6 2x4s keeping it supported all week, it became obvious that trick was to put more poles down a joist line every 12" or so with 1 or 2 on each side at the next joist. I had enough wood for about 3 or 4 in a row. Starting at one end, I wedged the drywall up, put in 1 or 2 screws every 8-12", them moved the back pole around to the front of the row. Put in another screw or 2, repeat. This REALLY turned into a challenge over the stairwell since every pole had to be a different size. The largest one was about 14'.
It took awhile but everything seems to be holding. I'll wait abit to spakle so I can watch the bare screwheads for signs of sagging.
Thanks to all for the advice and suggestions. If it holds for another 20 yrs, I'll be very happy. The lesson learned for me is not to ignore possible warning signs. The job wouldn't have been so complicated if I fixed it when the sagging first started.
--Jeff
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I think you owe that insulation contractor a six pack for 'hanging' the blown insulation with the vapor barrier! That was my main concern - that you wouldn't be able to get the drywall up tight to the joists with the insulation in the way. You lucked out. I'm sure it will be fine and won't cause you any problems from here.
R
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