How Level Ceiling Joist For Drywall

[JTTHECLOCKMAN]

How did we get to termites??? A few 2X3 studs sister to sides of joist. Run a level string line from end of room to end of room. Done in an hour. If there is termites I believe you better address this before you put the sheetrock up. Never heard of anyone shimming with cardboard.

[Robert Adams]

How did we get to termites??? A few 2X3 studs sister to sides of joist. Run a level string line from end of room to end of room. Done in an hour. If there is termites I believe you better address this before you put the sheetrock up. Never heard of anyone shimming with cardboard.

Cardboard shims are quite common. Though here they just don't try to shim it they just texture to cover up bad drywall work. 

      https://www.menards.com/main/building-ma...161477.htm

[Phil Thien]

Get (rent) a rotary laser and use cardboard to shim things before the drywall guys show.

If things are way out of whack...

Clamp 2x material to existing joists and level to the laser.  Use the existing joist as a reference to draw a pencil line onto the clamped 2x.

Take the 2x material down and cut to the pencil line with (if you have it) a bandsaw.  Now you have a scribed shim that you can tack back up to that joist and move onto the next.

Renting a laser can really speed things up and reduce a tendency to lower the ceiling more than necessary. It is also very handy to see just how things like ceiling boxes and HVAC fittings may need adjustment.

[APZ]

I do have a couple that are way out of whack and that's a great idea.  I have a laser level and a bandsaw; I'll be trying that.

[Phil Thien]

I do have a couple that are way out of whack and that's a great idea.  I have a laser level and a bandsaw; I'll be trying that.

You'll find that ductwork (even sheet steel) can be adjusted quite a bit once detached, so don't leave a 1/2" gap and rely on caulk once you're done, get everything adjusted before you call the drywall guys.

[EricU]

Cardboard shims are quite common. Though here they just don't try to shim it they just texture to cover up bad drywall work. 

apparently, the denizens of Happy Valley are real heathens, because the Borgs don't carry shims and there are no textured walls here either.

[NateClark]

You're fine if you have a ⅛" variance or less between joists.  You can achieve that tolerance by ripping a few shims in ⅛" increments on your table saw then use a straightedge (a straight piece of 4' framing lumber or a level) to quickly brad nail or staple shims to the required thickness.  score and break shorter piece as needed where the joists are convex/concave.

If you want to get fussy about it, you can hang a laser level so it's just barely lighting up the lowest spot of the lowest joist, then temporarily sister 2x4's with screws so they are barely touching the laser level, then scribe and circular saw the shims and attach with brad nails or finish nails.  If you sister then things get cramped for electric and HVAC and the hangers may accidentally fasten to the sisters causing the screws to reverse pop and let the drywall sag a bit.

Just out of curiosity, why aren't you hanging and finishing the sheet rock yourself?  Around here you would be hard pressed to fine someone who does good work to rock and finish a bathroom, unless they were a GC remodeling the bathroom for you.

[APZ]

I don't feel like hauling the material home and into the house.  I also hate to sand.  We have contractors around here who just do drywall.  Hopefully I can find a good one.

[mike4244]

If a joist is less than 1/4" out, leave it alone. The two joists that are lower, shim them and let the rockers do their work.
mike