Video: How to Hang Airtight Drywall (2 of 3)
Hanging the ceiling: Use drywall adhesive to seal between the drywall and each framing member, and try not to smear the adhesive when installing the drywall
Watch the video
Produced by: Colin Russell and Daniel Morrison
Myron: We're going to hang this portion of the ceiling first. We want to get the measurement for this first panel before we put any adhesive on the framing. That way it doesn't get all over our tape measure. We've already got the panel measured and cut. Now I'm going to go ahead and put the drywall adhesive on. I'm applying the drywall adhesive to each rafter, about a 3/8-inch-thick bead, a little past where the seam is going to hit, and all the way down to the bottom plate here. The drywall adhesive actually adds a little shear strength and reduces the fasten pops in my drywall, but it also will help seal these bays so it will reduce air leakage maybe from one bay to the next.
Now we are going to go up easy, and I'm going to try to place it in this corner before we push it into the ceiling. Now go up against the ceiling. We'll let it slide down slowly.
Justin: 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 barrierBuilding assembly components that work as a system to restrict air flow through the building envelope. Air barriers may or may not act as a vapor barrier. The air barrier can be on the exterior, the interior of the assembly, or both..
Myron: You'll notice how the adhesive is actually beyond the seam. I wanted that, because I wanted to make sure that I had adhesive all the way to this edge, because that makes a better air barrier. Justin, let's get ready to measure the next sheet.
Justin: 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.
Myron: I've been able to apply adhesive to each rafter, but at this little gap between the rafters, there is nothing there to actually apply adhesive or caulking to. But later on, I'm going to put a bead of foam in here. You'll notice that we had the same problem along the bottom. We had a little gap there, and later on we are going to put a bead of foam in there.
Justin: 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.
Myron: I'm looking good here. I float all the butted seams. I purposely place it between the framing and I attach it to a backer board, which creates a very stable and a recessed butted seam.
Justin: 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.
Myron: Notice how I shut the router off before I remove this piece of drywall. That way the router doesn't pick up any dust and blow it back in my face. I want to air seal around this outlet, but in addition to that, they are actually blowing cellulose insulationThermal insulation made from recycled newspaper or other wastepaper; often treated with borates for fire and insect protection. above this ceiling. So if I fill these gaps in, it will prevent that from blowing through. Because there is a little bit of dust there I just want to take a brush and get some out of the dust that was left by the router.
You can see that dust coming out of there. Now that would prevent the caulking from adhering. I'm just going to fill that gap - fill it right in.
Justin: Latex caulk is a better choice for this application because drywall compound won’t stick to silicone caulk.
Myron: The length that I want is 124. The actual measurement is 124 1/4, but we're going to back it off 1/4 inch and make it 124.
Justin: Cutting the sheets 1/4 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. Butt it tight to the studs, square to the adjacent sheet and lift it into place.
Myron: We're going up slow. See? See, that's how I would do it. Perfect. I've got to go to you about 2 inches. There we go. Now come to me. Now this seam is going to nasty over here.
Justin: 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 of this makes the ceiling a nice tight plane.
Myron: I've done all of the air sealing I can do for now, so we are going to go ahead and hang the walls.
Click here to see episode 3: Video: How to Hang Airtight Drywall (3 of 3).