Step 22b – Ceiling Drywall

The walls and attic are now air sealed. The cement slab was air sealed several months ago when I completed the framing, but several parts had deteriorated while it had been exposed to the elements so I touched up those areas. The only part of the conditioned space of the house that isn’t yet air sealed is the 2nd story ceiling. This will be done with drywall and spray foam.

Drywall is very easy to work with. To cut a piece to fit, you lightly run the blade of a utility knife so that it just cuts through only the thin paper surface of the sheet. Then, you can simply snap it so that it bends back away from the line you just cut.

You lightly cut through the paper on the other side to complete the cut. Any rough edges are quickly sanded with a couple passes of a drywall rasp.

The 2nd story ceiling drywall is secured to the bottom chords of the trusses with 1 1/4 inch coarse thread drywall screws. The drywall is attached perpendicular to the trusses, and staggered to improve strength. I lucked out in having a neighbor offer me use of his drywall lift so I didn’t have to buy one of my own. Installing 8′ sheets of drywall solo is possible with a little creativity, but the smaller sheets require more work to apply joint compound to the seams. The lift will allow me to use larger 12′ sheets so I will have fewer joints to worry about.

One at a time, I lifted the sheets up to the ceiling and screwed them to the trusses. It is important that drywall screws are installed perfectly flush to create a nice, smooth wall. I bought a drywall screwgun to help with this. The bit has a part that stops the screw from turning as soon as it is flush with the drywall.

Drywall must be attached on all four sides. This becomes a problem in many places because not every sheet ends on a truss. Many framers solve this problem by nailing more wood up, and then screwing the drywall into the wood. That wood is using up space in the attic that should be filled with insulation. I used metal drywall clips instead. These attach to the edge of the sheet and are screwed into the top plate of the wall. The screws will be covered by the drywall that we will hang on the walls.

Before the last sheet was hung, I went up in the attic and used spray foam to air seal all of the edges of the drywall to the top plates of the walls, as well as all the seams between the sheets and around gang boxes.

Next, I cut out a 22″x30″ rectangle in one of the gable ends and attached it with a couple of hinges. This will swing inward to allow me access to the unconditioned part of the attic. Attic access points are notorious for air leaks so putting the access on the outside removes that issue. I’m not worried at all about air leaking from the outside to the unconditioned space of the attic. The only worry is air leaking from a conditioned (heated or cooled) space to an unconditioned space.

The access point is just underneath the roof overhang so it is well protected from rain, but just in case I added some weatherstripping around the perimeter of the opening to ensure a good seal between the weather resistant barrier of the hatch and the wall. It will also be protected by siding.

With the access hatch complete, I could now install the final sheet of drywall, totally and permanently closing off the attic from the rest of the house. I entered through my access hatch and used spray foam to air seal the last sheet of drywall.

Closing the access hatch, the attic was completely dark and I could quite easily pick out any holes in the spray foam where light was coming through. The light shining on the plastic and spray foam gives them each a neon look. I crawled around the perimeter of the attic checking out every seam. The conditioned space of the house was now completely air sealed.

14 Comments on “Step 22b – Ceiling Drywall

  1. Thanks Matt for documenting your build. I’m following along and picking up ideas along the way.
    Question; any particular reason you forgo the poly and focused on sheetrock and foam for the ceiling? What about the seal in the transition between the ceiling sheetrock and to of the exterior walls?

    • Thank you for following Anders! Are you asking why I didn’t use a polyethylene vapor barrier in the ceiling? According to experts like Martin Holladay and Joe Lstiburek, vapor barriers can be dangerous, especially when placed in contact with insulation. There are quite a few great articles on the subject, but here is one: The gist of it is that if they are installed flawlessly, that’s great, but reality says there will be a pin sized hole at some point and that can cause serious issues. Myself being a beginner, I am not confident I could install it perfectly. The transitions between ceiling sheetrock and exterior wall top plates is air sealed with spray foam. I’m not sure if that answers your question or not but let me know and I can give you more specifics

      • You are right, GBA is all about air sealing and no vapor barrier.
        I have been looking at scandinavian concepts like where Greg La Vardera promotes the designs sucsessfully used in cold climates for long time.
        I plan a build in zone 6B where a vapor barrier might be useful (like often in Canada) but I’m still undecided.

        • Yeah, those are good. I don’t see why you would need a continuous interior chase like they show but you could plan out exactly where you would need it and utilize it there. I did all my plumbing on interior walls anyway. Have you read the Perfect Wall? In my opinion, that is the best information you can find on designing walls. Lstiburek has written entire books on this topic…

    • I attempted a level 5 finish with no texture. Skim coated everything. The walls turned out pretty good but the ceilings were far from perfect. Let’s just say I have a ton of respect for what you do! Drywall finish has been the most difficult part of the build to perform up to my standards. Respect for drywall contractors!

      • The finish is the hardest part for people who aren’t experienced with it. Unfortunately, the finish is the only thing people see, so a great drywall job can be ruined with a poor finish.

        • Much respect for you Joe, not only because I know how much skill a good drywall finisher has but also because not too many drywallers give two cents about air sealing.

  2. We normally use drywall mud for sealing all the gaps between drywall sheets, but spray foam isn’t a bad idea in some cases. The fact that you can see the light coming through as a way to see and inspect every seam from the backside is a cool method for looking for leaks. I like it!

    • Thank you Mitch. I tell everyone the hardest part of building the house was the drywall. Unlike everything else, the slightest mistake is highly visible and the lighting only highlights them. I spent countless hours skim coating and sanding and it was one of the few parts of the build that I will be subbing out for the next build. Many friends had advised me to sub it out but I like to figure things out on my own. They were right!

  3. Awesome content! Easy to see how somebody might think one type of drywall is good for an entire property, but it’s more nuanced than that. Choosing the proper material goes a long way in deciding the effectiveness and durability of your walls. Thanks for this handy guide

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