Detatched Garage Studio

Hi! I just bought a house in Los Angeles and want to build a studio in the 2 car garage in the backyard. It is an old stucco and plaster building built around the 1950's measuring 21'x19'x10'. The floors are mace of asphault just like the driveway and there is an existing concrete foundation around the perimeter. There is a wooden support beam for the roof right in the middle of the room. I record rock and country and music for film and TV so I want the room to be pretty quiet. I also play with a few bands and can get pretty loud. I don't have any immediate neighbors which is kinda why I choose to buy this particular place. My first concern is keeping sound from the street out, second is having the room acoustics sound good, and third is keeping the distant neighbors happy. I've been reading this forum for a long time and found it very helpful. I also bought the Build It Like The Pros book and its great! I just have a few questions that I need answered before I proceed with building.... To get started I've ripped out the existing ceiling because it was water damaged. There is a new roof now so things should be fine when I install the new ceiling. I am in the process of tearing out the asphault and am going to pour concrete in the floor. I am going to isolate the new slab when I pour it. I have a contractor doing that for me. I am replacing the big old garage door with a rool up door to save space. When the floor an ceiling are finished I'm gonna build four new walls inside and another wall 3 feet in front of the roll up door. My first big question is what to do with the existing walls. They are plaster walls on the inside and stucco out. Im going to build new walls right next to the old walls with new framing and everything. Should I: A: Build single leaf walls and leave the existing stucco where it is? I will frame them out, insulate with rockwool and lay triple drywall on one side. Will this create a 3 leaf wall? B: Tear out stucco first and proceed with the walls? This will be a 2 leaf wall? C: Build double frame walls with drywall on both sides? Keep in mind I'm planning on doing this already on the wall facing the roll up door. I will try to post pics and drawings soon but I need help asap on deciding if I should tear out the existing plater on the walls. Thanks!

I reposted in construction which seems like a better place...

hi there, the key to understand leafs -- and isolation -- is Mass - Air - Mass. So if you reinforce the stucco by adding mass directly to it (ie, layers of sheetrock/drywall), it will beef up the mass without adding a second "leaf." However, if there is an airgap between the stucco and the mass you add, that adds another leaf, which is not ideal, but sometimes unavoidable. So ideally, if you are going to stick to a 2-leaf system, you would beef up the stucco layer with more mass, and then build an inner wall frame, putting all the drywall on one side of your framing. Can you provide a diagram and pictures of your space?