How Level Ceiling Joist For Drywall

[Snipe Hunter]

I was hoping I could just shim up the 2 bad ones and that the others within 1/4" or so was good enough.  
 

It looked flat before I took it off, but there were 2 layers of sheetrock on the ceiling.

Two layers was probably not done by a pro. I'm assuming they did it because it looked like crap.

I usually rip 2x4s on my table saw and I've also used luan. It's cheap and cuts easily. I personally wouldn't fir perpendicular like in the photo unless it was horrible. Run a string across the joists to make it easy to measure. They don't have to be perfect, just close. I usually attach the firring with drywall or roofing nails. An 1/8 off won't be noticed but a 1/4 will.

[Snipe Hunter]

It is such a small area. I would sister some 2X 4's against each joist. Make sure they are straight. Make sure any lights or duct work fits. Mark these new studs so that is what you screw to. Level as level can be. If you try to shim you have to see if the entire joist is equally out and there maybe low spots. It is not structural and is just for a ceiling. This is the way I would correct it.

Solid approach

[JGrout]

Me I would KIS 

just shim it

[Lynden]

Me I would KIS 

just shim it

Cardboard shims are freeways for subterranean termites. When I straightened my walls and ceilings I used 1-1/2" x 8' strips of 30-pound felt (cut from a roll) to shim out the low spots. The high spots were removed with a power planer.

[APZ]

Two layers was probably not done by a pro. I'm assuming they did it because it looked like crap.

I usually rip 2x4s on my table saw and I've also used luan. It's cheap and cuts easily. I personally wouldn't fir perpendicular like in the photo unless it was horrible. Run a string across the joists to make it easy to measure. They don't have to be perfect, just close. I usually attach the firring with drywall or roofing nails. An 1/8 off won't be noticed but a 1/4 will.

Thanks Neil and everyone else.  I think this is the route I'm going to go with. 

What happens with a small gap between the sheetrock and the HVAC ceiling vents?  Will the drywall contractor take care of that with caulk or something or should I be doing something?

[JGrout]

you have termites in the attic spaces you have far bigger problems than cardboard shims.

[Robert Adams]

you have termites in the attic spaces you have far bigger problems than cardboard shims.

True. Now you could get some carpenter ants in there and they will take care of the termites but the ants are harder to get rid of than the termites are.

[Lynden]

you have termites in the attic spaces you have far bigger problems than cardboard shims.

http://thehouseholdpests.org/img/termite...rywall.jpg

I said walls and ceilings. Subterranean termites will eat anything containing cellulose in a stud bay, including the paper backing on drywall and the kraft paper on insulation. Why introduce more cellulose in the form of cardboard shims when there are alternatives.

[ronlaughlin]

Good grief, it is a small space.  Just rip strips, and nail them to the joists so that all is in the same plane.  Strength is not compromised.   Just inform the dry wall hanger to use longer fasteners, so they are attached to the joists, not just the furring strips.   Me, i wish all the problems in my life were so trivial.

[JGrout]

Again the joists are wood, the cardboard is also from trees and the termites will feast on more than cardboard if they get that high up.


So either way the structure  is still compromised, IOW it was over before you even knew it .

just saying