The design has been tweaked few times over and I'm set to get this thing completed. Below are the final plans from which I'll be working.
The first wall was assembled and once it was ready to go up I discovered my first planning issue. The supports holding the silencer box are in the way, and the opening is to low so the box will need to be raised. I pushed the box up with another brace, then climbed into the attic to put a 2x4 across the truss to hold the box up out of the way. Once that was done I stapled the insulation to the furring strip across the top and the wall was able to be set in place.
With the east wall up (windowed) and first north and south wall holding it in place, you can see how this inside out room is going to look. I have a 4" air gap that will surround the new room and a layer of insulation between. At the time I had finished this part of the construction I was thinking I'd be getting proper glass and make a nice window, but prices of materials have gone up in the pandemic and that glass looks like its going to be way out of the budget. I have to keep the window as a means of egress to comply with code so most likely it'll be sealed off by shutters made to be inside out like the rest of the room.
I had to screw the silencer box to the trusses to keep it out of the way while the first wall went up. Once it was in place though I was able to tack down the 2x8s that will turn into the support beams that will be holding the box up. With the plans and measurements all laid out, assembling the walls was actually a really quick process. These panels got heavy. At one point as I was trying to do it all by myself, I was pretty sure I broke a finger when the ladder folded in on itself as I was trying to get one of the 250lb ceiling panels up. Help was definitely required to get everything in place without dying.