a couple more random questions..

1. can someone point me to a link that shows the proper type of HVAC duct that I should use? All I seem to be able to find locally is plain old galvanized stuff. 2. Any recommendations on a low-noise register for HVAC? I've seen some mentioned, but haven't been able to find one. 3. sway-braces/wic clips - obviously, I need these between my existing walls (foundation) and inner leaf walls that run along the foundation. What about the 'inside' walls - do I want to use them between the 2 leaves of the wall between control/live room? Thanks!

I'm not the most qualified to comment on your duct question, but I'll try to at least get you pointed to a stating point... Obviously HVAC is a seriously complex issue that when done right, it's what will make your studio... and when done wrong... ooooof. First, the main trunks... Your trunks are typically a galvanized trunk, like you are already finding. Then they are lined with a rigid insulation like a Johns-Manville or Knauf duct liner. One thing I ran into was a county code wonk... Since my HVAC is in the attic space above the studio, our inspector's require that all galvanized duct be wrapped on the exterior with a minimum of R-4 insulation. Regardless of whether the duct is lined or not, this was a requirement that I had to meet. The reason is because of condensation that forms on the exterior of the ducts during the long cooling season, has a tendency to cause rust and degradation of joints. I mention this is because you're in GA, and may run into the same thing. Home Depot has flexible duct that at least you can start with looking at. It's an R-6 rated duct, from what I can tell. There's also QuietFlex and Thermaflex for starters. There are plenty of others out there to look at... almost too many. In my case, I already knew that the HVAC was well over my capabilities to handle. So, I contacted a bunch of contractors to try and get the best price. The contractor I settled on wasn't the cheapest, but the one who had the most experience in dealing with high-end home construction and at least knew what the goal was for getting the system as quiet as possible. e.g. long sweeping bends, the importance of keeping smooth transitions, etc. I'm still on saw service power, so I've not fired up either of the units yet, so I'm still crossing my fingers that we're going to have a quiet system, but at least I'm confident that if there is a problem, that the contractor WILL resolve the issue... and it's all at his expense from this point on. Low noise registers are something I'm going to start on VERY soon... like in the next few days. :) I'll actually be building my own. Essentially, they are simple slats that will direct the air straight down. (All of my supply boxes are ceiling penetrations.) The plan is to ease the edges of the slats to a 1/4" radius to reduce turbulence and thus noise. HTH, Max

Thanks, Max.. that does help. I'll most likely bring in some pro for HVAC - but like everything else, I'm researching it like I'm doing it all myself.. I want to know EVERY detail of what's going on, so I know if it's being done right or not. I was planning to do soffited ducts for my supply and returns - you mentioned ceiling penetrations for yours.. I could get away with ceiling (I actually have about a 14"x19" joist space to run ductwork over the rooms), but I thought that soffits provided better isolation from 'upstairs' (this will be built in a basement with 10' ceilings). You're in the RDU area? Not TOO far from me, so I suspect we'll run into the same thing. HVAC-wise, I'm seriously leaning toward using my mechanical room as an exchange chamber - and tapping into the existing HVAC to cool and heat that room. Normally, this seems to be a no-no - but the area where I'm building the studio was designed into the house as a 'home theater' area.. so it was designed to be part of the whole-house HVAC (with a good bit of electronic equipment and a half-dozen people). The mechanical room actually contains two different air handlers covering 3 zones in the house - so I can actually tap into both to make sure I get adequate cool/warm air. As it is - the area that I'm building stays very comfortable with the existing supply (from just one of the two air-handlers) - I suspect tapping into both will give me plenty of cool/warm air. I certainly need to check all the calculations, but this area was designed to house a bunch of people and electronics.. so I suspect I should be good.