yet another studio...

Hi again, We're starting to build a studio on the top most 5th floor of a commercial building. The building is pretty much empty except for a shirt press on the second floor and some storage spaces on the 5th floor. Our band's rehearsal room has been in the building for some time and now we're going to add a control room to make it a proper studio. We occupy 4 rooms total in one corner of the building. The current CR, live room, a PA storage, and the future control room. So far the live room itself is not isolated at all, just your typical empty timber frame walls with a layer of chip board on both sides. The floor is a concrete floor with that cool 70's linoleum finish. The outside walls have huge windows all across the building. The live room ceiling is acoustically treated and the room actually sounds very good. Originally the building was a press and it was therefore made to accomodate the very heavy machinery used. So from isolation point of view that's great. We've been recording in the space before and there are no problems with noise going out(since there's pretty much no one to hear it...) or coming in so far. We will initially isolate the live room also but for now we want to have the control room built and isolated. The CR is on the other side of a wall from the live room so we will have good visual between the rooms. I've been drawing for about a week now and came up with a plan. I will present the plan in sections so everything gets covered as best they can. So starting with the outer layer of the CR. The room itself is 7,2m x 4,5m and 2,75m high. All the surrounding walls are the same empty timber frame and chip board on both sides except the outside wall which has 1,95m x 1,2m windows running along the entire outer wall. So 6 windows total... The CR also has windows up above the doors running across the whole room which of course need to be covered with rock wool as well. The basic idea is to divide the room so there'll be a small storage space behind the CR. Here's the first part: -The wall between CR and live room 1.Take out the chip board sheets from the CR side of the wall 2.Put new studs in to form the CR/live room window frame 3.Glue and seal the taken chip board back to the cavities to increase the mass 4.Glue and seal another 1 or 2 layers of gypsium board on top of that 5.Add a layer of 100mm rockwool to the wall Here's the cross section of Live room to CR: 2 layers of chip board and 2 layers of gypsium board-100mm rock wool-100mm air cavity-3 layers of gypsium board-100mm rock wool How does that sound? We can get a lot of rock wool for very cheap so if you think we need thicker layers of it, please let me know. Now I do have a couple of questions, surprise... What would the TL be of the first mass wall? We ordered dB-rated windows and according to the manufacturer the TL of this double window is 51 with 150mm air cavity. I can't remember specifically the thickness or TL of the individual windows but I'll find out on monday and let you know. I don't want to make the walls overkill because the windows are the weakest point but I do want to make them thick enough for best isolation possible... :blah: My second question is a bout the wall between the hallway and the CR. The construction is similar(chipboard on both sides of an empty timber framing). Could I just add gypsium to the CR side of that wall without pulling out the chip boards? This would make it a three-leaf system once the inner frame is built. I want to get the outer structure right before I start talking about the inner frame and acoustics etc so I won't post the whole plan just yet.

Hiya - I can't help with your questions but good luck with the build. I am trying to research building a private rehearsal/recording set up in office space in Helsinki - I am really interested in how the legal, permissions, and approval process works. If you do carry on with your studio diary here I would really appreciate some info on the Finnish system:) Good luck!