How to Hang Airtight Drywall on Ceilings
When placing the sheets, be careful not to smear the caulk or adhesive too much. The framing is only an inch and a half wide, so smearing it can seriously compromise the integrity of the air barrier.
Floating the butt seams allows faster drywall hanging and cleaner seams because you can use a recessed seam backer to pull the butt ends back where mud would otherwise build up.
Now with the sloped part of the ceiling done, we move to the flat part. For this, the author uses a drywall lift, which allows him to carefully place these 12 foot sheets of 5/8 in. drywall without smearing the caulk.
Holes in the ceiling for junction boxes or light fixtures are cut out with a router and then sealed with caulk. It is better to seal holes with caulk after the drywall is attached as opposed to before hanging the sheet, because the drywall router or saw might damage the caulk joint.
Latex caulk is a better choice for this application because drywall compound won’t stick to silicone caulk.
Cutting the sheets a quarter inch short is a good way to ensure that the sheets will fit. In this instance, they also cut a notch for the large piece of conduit running down the wall. Again, all of the gaps will be sealed with canned foam later.
Again, it is important to get the sheet squared up before pushing it up tightly against the framing, and consequently, the adhesive. But it tight to the studs, square to the adjacent sheet and lift it into place.
One of the tricky things about old framing is that sometimes it is not square, which means a gap somewhere in the drywall seam. For big gaps like this, cut a custom patch, pack it in and cover it with mud later on.
After completing the ceiling, apply canned foam along the perimeter. Let it expand out, and come back later to cut it off. All this makes the ceiling a nice tight plane.