Double stud 16" wall or....first post yeah!!

Hey Jim, you should build two separate walls because of better decoupling and the 4" airspace is good. For reference look here and here. I hope that helps. Cheers, Carsten

Hi Him, and welcome aboard!

As of now the wall could be aprox. 16" thick double 6" stud with a 4" air space. Should I have separate bottom plates for each side? (6" bottom plates for each row of studs?) in essence build two one sided walls? with the air gap, leafs on the outer sides only of course and have the bottom and top plates of one wall decoupled from the other wall all the way up until the struts? or.. have a 16" bottom and top plate? also is a 4" airspace alright?

It sounds like you have the right idea, except for this part: "I will be putting up a wall dividing the tracking room from the CR." Only one wall? what's the use of that? You need an entire ROOM, with four complete walls and a ceiling. One wall won't do anything at all for you, except make it look pretty. And this part: "...decoupled from the other wall all the way up until the struts?". They need to be decoupled all the way, period! Not just "up to the struts": There must be NO connections AT ALL between the two leaves of your wall. Each room is a separate "box", inside the house itself, which is another "box". You need to think of building it like two shoe-boxes (your rooms) inside a large hat box (the house). The only place where the boxes are in contact, is the floor. All other surfaces are totally disconnected and decoupled, and sealed air-tight. Nothing touches anything. If you don't do it that way, there is no point in doing it at all. One wall by itself is a waste of your time and money. You also need to make sure that you have ONLY TWO LEAVES in any direction. Not one. Not three. Two, and only two. So basically: The existing walls of the house are your outer leaf for both rooms, and you will be building two totally separate new rooms inside that. Which means that you will have to remove the sheetrock from the inner surface of the house walls, leaving only whatever is on the outside of the house (siding? stucco?). You will then need to "beef up" that outer leaf, using the sheetrock that you just removed: Cut it to shape, and fit it between the studs of that outer wall, pressed up tight for good contact, held in place with cleats, and sealed all around with caulk. A couple of layers of that should be enough. But you didn't say how much isolation you need! (All you said is "I don't have to worry so much about bothering anyone", but that isn't very helpful! What about external sounds that you need to stop getting in? (Traffic, aircraft, wind, rain, noisy neighbors, lawnmowers, animals, etc.) You need real numbers. If you don't have them, don't guess: measure them with a sound level meter. You should read this post and do everything it says before posting again.) Anyway, when you have done that and sealed your outer-leaf air-tight, fill the spaces between the studs with insulation (rock wool or fiberglass). If there was already insulation in there, you can probably re-use it, to save money. Now you can start building your actual rooms. Separate stud frames around each room, no connections at all, built about 4" in from the existing frames, and on separate bottom plates. At least two layers of sheetrock on the inner sides of those studs, with a layer of Green glue between. Staggered joints between layers, backer rod in the gaps, seal with caulk, tape, mud, etc. Now build your new ceiling across the top of each room, in the same way: joists, two layers of sheetorck with Green Glue, lots of rock wool up above. Seal air-tight. Once again, no connection between the new ceiling and the roof above, nor between the ceilings in each room: they are totally separate ceilings, one for each room. That is your second leaf. Fill the entire gap between the two leaves with insulation, as much as you can afford, and make sure that both leaves are sealed hermetically: If air can get in or out, then so can sound, even through a tiny crack. That's it!