Post and Beam Shop Build

Hello, I have been lurking/researching on this great forum but I am a little confused on an issue. My goal is to convert my 48’x30’ post and beam shop into; Control room approx 13 x 21 x 11, Iso booth approx 9x13x10, Live room approx 21 x 28 x 11. One 12 x 30 section will not be built out and reserved for garden tools etc. (Photos and drawings of existing pole building type structure attached.) I plan on a lot of listening, mixing time, and maybe messing with video in the control room. I would like to play and record some rock and roll with some pals…definitely loud. I own a sound meter but haven’t had much use for it until now…There is only 1 house across the street approx 100 yds away. My house is 60 yds away. Otherwise I am surrounded by national forest. I am in the planning phase and have time and money to throw at this project to do it right. I have a lot of experience framing and finishing houses and commercial buildings before I became a dentist. I enjoy building and for me the process of this build is part of the goal. My finished studio will be true rooms within a room. At this time I am looking for the biggest bang for my buck for sound dampening/reduction with the existing structure before moving on to the interior. My questions; Should I mount RC on the existing OSB wall and hang two 5/8 sheetrock or attach two layers of sheetrock directly to the OSB? (With green glue caulking to seal edges.) I think the latter but wanted to verify. Similar question for the ceiling. Two layers of 5/8 directly to the rafters or attach RC to rafters and 2 layers of 5/8 sheetrock? I plan on Roxul insulation on ceiling. Thanks in advance... Jim ---------------- Sorry I forgot to log in before my post :shock:

Sorry I forgot to log in before my post

No problem! It's a little quirk on the forum right now: it shouldn't let you do that, but for some reason that I haven't figured out yet, it does. But I fixed your post for you... So Welcome to the forum! :)

Control room approx 13 x 21 x 11, Iso booth approx 9x13x10, Live room approx 21 x 28 x 11.

Did you check those with a room ratio calculator (room mode calculator), to make sure there are no red flags?

definitely loud. I own a sound meter but haven’t had much use for it until now…There is only 1 house across the street approx 100 yds away. My house is 60 yds away. Otherwise I am surrounded by national forest.

OK, but do you need isolation? I doubt the animals in the forest will turn you in for violating the noise regulations (but beware of rabid environmentalists! :) ), but going the other way their are lots of noises that might disturb your recordings. Animals, for example, or wind, rain, thunder, hail, aircraft, etc. Or noises inside your own house: radio, TV, vacuum cleaner, phone, etc. So do consider all those when you come up with your number for isolation.

I have a lot of experience framing and finishing houses and commercial buildings before I became a dentist.

Framing -- dentistry... Yup! I see the connection! :)

At this time I am looking for the biggest bang for my buck for sound dampening/reduction with the existing structure before moving on to the interior.

Sound isolation (a.k.a. "soundproofing") is actually a system comprised of both parts. It's not the the outer wall stops sound and the inner wall is decoration. It's that the outer wall and inner wall work together as a tuned system to stop sound. Change something in either of those walls, or even the gap between them, and you change the isolation. So you should approach your design from that point of view, taking the outer and inner as a combined unit, with all parts working together.

Should I mount RC on the existing OSB wall and hang two 5/8 sheetrock or attach two layers of sheetrock directly to the OSB?

If you are going to do true "room in a room" construction, then neither! :) Your outer wall can be only one "leaf", and your inner wall provides the other leaf. The outer wall has drywall (or OSB, or plywood) only ONE side of its studs, and the inner wall has drywall (etc) on only ONE side of its studs. Each set of studs has "stuff" on only one side, for a total of two leaves. You should never have three leaves, even less four leaves, as that would reduce your isolation for low frequencies. 2 leaves, and only 2. Each leaf can be built up from several layers if needed, ut they all go on the same side of the studs. So a leaf for very high insulation might consist of 5/8" OSB directly on then studs, then 5/8" drywall on top of that, then a layer of Green Glue, then a final layer of 5/8" drywall. The system looks something like this: Or you can also do the inner-leaf "inside-out", like this, which has significant benefits (both acoustical and practical): If you have several rooms, then your outer shell is one leaf, and each inner room is it's own leaf, as follows: Ceilings are the same: each room has it's own independent 1-leaf ceiling that rests only on that room's own walls, and the entire outer-leaf has one single leaf of roof. RC is meant for those situations where it is not possible to build a separate stud frame for the inner leaf, and the drywall has to be on the same studs as the outer leaf. In that case, the RC provides a reasonable level of decoupling, so it is a good solution, but that's not your case since you said you are going to do full room-in-a-room construction. So you do not need RC.

(With green glue caulking to seal edges.)

Careful there! The Green Glue company makes several products, only one of which is acoustic caulk: You use that for sealing gaps and cracks. Their flagship product is Green Glue Compound, which you spread between the layers of drywall. That is not caulk. And it is also not glue! (Despite the name). It is a special viscous-elastic polymer that provides constrained layer damping between the drywall sheets. That is very important for low frequency isolation, and very effective. So that's the way to do it. - Stuart -

Great clarification for me thanks so much. I am still digesting and will incorporate your ideas into my build. Yes, I've been playing with the room calc and the size of the rooms will be adjusted. I can pretty much make them "ideal" without losing very much space. Excellent point about my true isolation requirements I need to reconsider. Wind and rain noise on the metal roof would be a problem but not much else. Fortunately the environmentalists are pretty unwelcome in this county :roll: I am planning 2 5/8 layers of sheetrock on "outer" existing walls and ceilings and 5/8 and 1/2 on the inner. From reading this difference in wall masses with be more effective for a broader freq range? Insulation and air gaps uniform all around..etc. About the drywall leaf of the inner room being on the outside... I know this makes resonators and bass traps easy to integrate but what do people do for esthetics to cover the studs? Thank you so much!! jim

and 5/8 and 1/2 on the inner. From reading this difference in wall masses with be more effective for a broader freq range?

well, yes, there is a slight advantage to having materials of different thickness or different density, but that advantage disappears when you also take into account the other aspects: total mass, stiffness, resonance, coincidence, etc. For example, with the 5/8 + 1/2 plan, if you make them both 5/8, then you have more mass, more stiffness and the coincidence dip rises to a higher frequency, all of which are good. You lost the slight advantage of having different resonant frequencies, and the slight advantage of the impedance mismatch across surface boundaries, but overall you gained more than you lost. Better still, what you lost is mainly applicable to high frequencies, which are easily isolated and which you had covered anyway, and what you gained is all in the area of low frequencies, which are always a bitch to deal with. In other words, just do everything with 5/8" fir.rated drywall, and you'll be maximizing your isolation.

I know this makes resonators and bass traps easy to integrate but what do people do for esthetics to cover the studs?

Normally: acoustic fabric. Just stretch it across the studs neatly, to hide the "ugly". Some people then put broadly spaced wooden slats over that, mostly for aesthetic reasons, but also to keep the highs in the room, without loosing too much into the absorption. - Stuart -