Installing/fixing ceiling drywall when trusses are uneven?

Question

My house is an "L" shape where the short leg of the "L" is the garage. Above the garage ceiling, the trusses transition from one orientation 90 degrees to another orientation. The different orientations of trusses are different heights above the floor.

This means one-third of the ceiling has the bottom edge of the trusses 1/2-inch lower than the other two-thirds.

When the ceiling drywall was originally installed, the drywall was butted up at this uneven transition and caulked. This joint has failed over time, and then wind blows through the joint (when the garage door is open) making the problem even worse.

What is the proper way to fix this situation?

Answer 1

There are a few solutions for such a problem.

What I would do is mark the locations of the joists on the higher drywall, and then glue and screw new half inch drywall right on top of it. (Or 3/8" or 5/8" depending on if it's not exactly a half inch difference.) This will most likely be the cheapest and easiest option.

You could also remove the drywall, sister wood or steel studs to the ceiling joists at a 1/2" offset and then reinstall drywall. This Fine Homebuilding article has a more detailed description of the process.

Answer 2

You'll have a header running across the 90° transition in the framing direction, so this shouldn't be that difficult to fix. I'd remove the drywall from the last stud bay (shaded below)...

...and attach blocking to the header that will catch the sheetrock. Since you're getting air ingress there, I'd take the opportunity to insulate while you have it open. I'd also use fiberglass tape instead of paper along this joint when you put the drywall back up - I've found that it tends to hold up better along seams like this.

Answer 3

The higher section could easily be furred down (after removing the drywall) with strips of 1/2" plywood.