The first steps in construction are to tear out the old rock band sheets and fiberglass, box in the furnace, and fix up the drywall for painting. These steps are pretty much independent of any acoustic treatment I'll need to do, so I can get started. I also assume I will have some treatment on the ceiling, so I can put in some studs to support whatever ends up there.

Here was the room when it was set up for band practice:

Carpet on the floors, R13 insulation tacked to all walls, covered by sheets. Draped sheets on the ceiling. The room was quite dead. Before tearing the old treatment out, I used ETF to measure the RT60 in this room, as shown in the following graph:

As one might expect from the carpet and insulation, the room is (was) very dead, with an RT60 of around 100 ms at higher frequencies, rising somewhat at lower frequencies.

Photos of the first steps, in progress, after tearing out the wall covering and insulation from the practice room:

Same corner as the earlier band room shot. Note the garage door opener coming thru the wall. This is going to be a challenge.	The southwest corner, where I envision the mixing console going. The garage door rail is going to be a challenge here.
Exterior door	Furnace and hot water heater, starting to be boxed in.

Fixing up the walls was more of a challenge than I'd expected, and brought back a few memories. The room had been built when the boys were about 14, and I'd supervised but let the budding punk band members do most of the work of putting up drywall and so on. I recall that, much to my amusement and surprise,  the drummer, a very strong, athletic type, later a football star, had never used a hammer before. Going over the walls, this was pretty evident, lots of bent nails, nails that had missed the studs, hammer holes in the drywall, and so on. They'd patched up the cracks with spackling, and there were gobs of it everywhere. I tried to smooth this all out, but it's never going to be mistaken for a professional dry walling job.

But making progress:

Boxed in furnace area. I dicovered there was some space to be had in this box, and added room for tow cabinets in the side. Slatted doors seemed the safest bet around the furnace even tho it won't help with noise. The empty areas are reserved for some type of sound panels, TBD.	My solution to the garage door opener and track was to build a round box around them, looking a bit, and hopefully functioning a bit as a poly/diffusor.
Finished "poly" box around the grarage door track. Also added some paint by now. Low voltage downlights in the poly. Also angled off the corner, using an old door. The door is hollow and fairly thin, and may provide some bass trapping. The corner behind it is filled with fiberglass.	Poly around the grarage door opener

That sort of completes the major raw architectural elements I want to address. Now it's on to sound issues.