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While time-consuming, the process of getting drywall installed, mudded, and sanded was surprisingly pleasant.
Installation and trim
We follow the 3-1/2" flush base technique from Build's blog post. After mounting the wall board, I trimmed off the lower four inches and screwed on Z-metal to provide a reveal and gap above the 1x4 base stock. The Z-metal trim isn't easy to find but I managed to get it from Steeler.
The door jamb protrudes to the same depth as the framing members. The wall board sits flush against the face of the door frame, held back about 3/4". The door jamb is kerfed to receive a piece of L-metal that cleanly finishes off the side of wall board. After tape/mud/prime, I applied a small bead of Big Stretch Caulk to the inside corner between the jamb and L to cover any minor imperfections in the kerf.
The L-metal is even harder to find since you need it with at least a 1" long leg to properly seat the leg in the kerf after coming around the 5/8" wall board. I was finally able to get some from GTS which curiously is just one block away from Steeler. The stock I found is paper-faced, flat on one side, and beaded on the other to receive the joint compound - perfect! (Except it took a week to source it.)
The windows are trimmed out with VG fir 1x6 stock that is kerfed just like the door jamb to receive L-metal.
The one exception is the side of any window that is next to a corner; in that case the wall board of the incoming corner wall terminates straight into the window jamb with some U-metal to keep the cut crisp.
The bottoms of the windows were positioned such that the top edge of the horizontal window jamb/trim is at the same elevation as the underside of the Z-metal on the rest of the walls. This resolves the window corner condition where it transitions to wall and allows the base trim to run continuously and at the same height along the wall and windows.
In other words, getting this right required precise planning and 1/8" precision and alignment from the day I planned the rough framing and ordered the windows, through final trim and flooring installation. Good times. It's nice when a six month long plan comes together.
We also wanted some configurable bookshelves on the window wall underneath the clerestory, and I happened to have a spare stick of
recessed display shelf standard
SSRB-11B8) floating around from my library shelving project, so that got cut in half and mounted.
It's a bit extra to mount since it is deep enough that it has to sit on a recessed stud, and then the stud itself
needs a slot cut down the center to accept the back end of the shelving brackets, but at least this time I'd already figured this out
and prefabbed partial studs in the shop and just glued them on to the sides of existing studs.
Mudding and sanding
After much internet research (and some trial and error) I figured out that the following are the three kinds of drywall mud to use, in the following order:
- Hot mud is akin to concrete or mortar: it comes as a dry mix in bags, you mix it with water once you need it, and it sets up fairly quickly (I choose a 45 minute set time version). It's a good first step to use to cover large gaps because it cures by chemical reaction, not by water evaporation, so it's less liable to contract on larger gaps. However, sanding it is about as much fun as sanding concrete, so use it only as a first coat that doesn't need sanding.
- Joint compound is an excellent second (third, ...) coat on top of any initial hot mud coat you may have. Get it premixed, but do toss it into a bucket to re-mix it and consider adding a bit more water to it if it doesn't spread well. Apply with a 6" wide knife, then a 9" wide knife for the second joint compound coat. Sand after each coat. You will end up with little air pockets in it and that's okay.
- Topping compound is a great final coat to fill in whatever little air pockets and other tiny imperfections you might have had in the penultimate coat. Supposedly you can just throw some dish soap into joint compound to manufacture your own topping compound, but I chose to spend the extra ten bucks to get a pre-made one.
I found it to be quite worth it to go through the relatively minor trouble of sourcing three kinds of compound rather than just winging it with all-purpose. I've ended up with a better drywall finish than I'd even hoped for and I think it's largely due to that diligence.
For sanding drywall, it's absolutely worth spending the money on sanding screens and a good holder for them rather than using sandpaper (which would just clog up instantly).
Make sure you have a good vacuum, vacuum often, and clean your vacuum's filter often. Get a soft brush to put on the end of your vacuum's hose.
I primed with Kilz 1-2-3 rather than some cheap-o primer and it went on quite nicely. We top-coated with Sherwin Williams Cashmere paint; it costs about twice as much as any paint at Home Depot but it also went on quite nicely in a single coat so that saved a bunch of time.
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