Plans for Rehearsal Space in Berkeley Garage: Feedback?

I live in Berkeley, California. I am remodeling a 2-car garage into a rehearsal space (not a recording studio). We have neighbors on 3 sides. The nearest is 25 feet away. The intended use is for live jazz. Not rock 'n' roll levels, but there are drums and amplified bass & guitar. I get an A-weighted db reading on my Radio-Shack Sound Level Meter of 85 (slow setting) when the group is meeting in my living room. I have the help of a contractor who has done this (room-within-room) before with very good results. But this is a bigger project. The scheme is for a room-within-a-room assembly of the sort recommended in Rod Gervais' book. Double framing. Internal wall will be double 5/8" sheetrock with GreenGlue, insulation, and minimum 2" airspace. External walls are insulation, 1/2 " plywood on wood studs, and 7/8" stucco as siding. It will all rest on a concrete slab. The ceiling is the same treated rock. I've had a structural engineer weigh in (excuse the pun) on reinforcement of the ceiling, as it's rather long. This will be done with 2 struts. None of this internal assembly will be tied to the outside. In the plans I am posting here (a bit crude, but I hope they get the idea across, and most of the specifics), I have taken the dimensions of a studio design by Wes Lachot that I cribbed from the realtraps.com website. It has an 8' ceiling, and happens to fit very neatly into my available space, leaving room for an angled corridor with some storage space. Perfect - or so I hope ! Here's my source: http://www.realtraps.com/art_studio1-big.gif I'm accepting all criticism. Foremost among my concerns are: 1) Am I getting into problems by having so much space between 3 of my nternal walls and my external walls? Like building up low frequencies? And, if so, can I diminish that problem by treating the space between? My friend hung fiberglass panels like flags from the rafters to help with this sort of issue. His source was: www.atsacoustics.com 2) What would you recommend for windows? The intention is for a big 5 x 4 foot double-pane window with a companion window on the other side of the air-space (see plans). Rod's book has suggestions for calculating one's needs as far as mass / glass thickness, but he is assuming a studio app., with visibility needed between control room and tracking room. I am trying for sunlight from the outside world & thus framed window / airspace / framed window. We are unclear, with 2 double-pane windows, if we are getting into the 4-leaf effect. I'm also concerned - alternatively - about overkill. Perhaps we don't need a double-pane window in the outside wall when it is surrounded by simple plywood and stucco? And I'd love to hear from more experienced minds about thickness of panes with my scenario. I do understand that laminate glass has good properties for this application. As a final note, I am probably not going to splay the glass in the double-pane window (or windows), as reflections are not as much a concern as is the isolation value of the window. 3) Is my weakest link the roof? Above our 8 foot sheetrock / GreenGlue ceiling, we will have a roof of 1/2" plywood, caulked, with composite shingles up top. We will be very careful to caulk all seams in both the internal and external walls, but I am wondering if the roof is going to undermine my efforts. Your guidelines ask for budget: We're budgeted at 33 k for this whole project (starting with the garage torn down to its bare studs). This includes electrical, purchase of AC unit, lighting & miscellaneous. I am not including acoustic treatment of the finished room. Thanks very much - in advance - for your time ! Clark Suprynowicz Berkeley, Ca.

given the amount of space around the room you're talking about, i think you could try to use the double glazed windows to get the light you want. certainly sealing up the rooms as well as possible is a good idea - noise, energy efficiency, insects... will you need additional absorption outside the room? maybe. since you have it all open you could add it later if you found it to be an issue. since you're going to be adding insulation in contact with the new drywall, resonance issues from the panels should be minimal.

Those windows are really my concern right now. Appreciate your thoughts, Glenn. When you say: "i think you could try to use the double glazed windows to get the light you want" Makes me think I should be more specific in my question. Should I: 1) Have a double-pane window assembly in the interior wall AND the exterior wall, or 2) Have a double-pane window assembly in the interior wall, and an ordinary window in the exterior wall (the exterior wall, as you see in my plans, is less formidable: just plywood and stucco on wood studs). 3) Given that options 1 & 2 don't include specifics (such as thickness of glass), can you tell me what specific recommendations you'd make for whatever combination you'd like to see? Page 89 of Rod Gervais' book gives a way of calculating appropriate thickness of glass, but I'm not secure making this calculation given that my example is so different from the ones in his book: I've got a window, 2" of airspace and then yet another window, rather than a single assembly.

I found a reference on your forum to a situation like mine. Apologies for not finding this before. I searched for "Four leaf" & found a fellow who was trying to ameliorate sound from the street by putting windows over his windows. Here's Mr. Gervais response: Posted: Tue Jan 22, 2008 12:49 am Post subject: Reply with quote I wouldn't go that route - (Normal window installed inside of) There are companies out there who specialize in sound attenuation windows for city settings - and they work pretty well. If you just stick a standard window in there - you created a 4 leaf system with thin annealed glass - whereas the specialty windows are constructed with thicker laminated glazing. Check your local listings for specialty soundproofing windows - and get some quotes. I have had good luck with these in NYC. Rod So, it's true - the 4-leaf effect is alive and well with windows ? All windows, thin annealed glass or otherwise? For now I take it that I should avoid double-pane window (of any kind) plus double-pane window. Can anyone give me a recommendation (thickness) for a single sheet of glass mounted in a wood frame with the appropriate neoprene setting blocks? I believe I will want laminate glass for the interior, but not laminate for the exterior window (the Green Glue site informs me that laminate glass loses its superior abilities in cold weather). It seems to me that the idea is to match - or exceed - the sound isolating qualities of my 2 layers sheetrock / Green Glue assembly on the INSIDE wall. And to match or exceed isolation of my 1/2" plywood / 7/8" stucco on the outside. I suspect I've set myself up for a very expensive piece of glass by specifying a 5 x 4 foot window. Is this madness? I can scale back. ____

Hi Clark, You've got it! The general rule of thumb around here, is to use glass 1/3 the thickness of your plasterboard walls. That's based purely on mass, with the density of glass being roughly 3 times that of plasterboard. Using Green Glue changes that relationship in favour of the plasterboard, especially for lower frequencies. You'll have to make a judgement call on that yourself, and price will certainly be a factor at those thicknesses! You'll probably want to have a look at the Knightfly's handy Material Densities post.

quiet wrote:

I suspect I've set myself up for a very expensive piece of glass by specifying a 5 x 4 foot window. Is this madness? I can scale back.

Probably madness, but quality is remembered long after the price is forgotten.

Appreciate the guidance, Adam. I'm putting this all together, a piece at a time.

Adam, I wonder if you want to weigh in on a change in my plans. This has been prompted by a lot of talking-over the nature of building in a garage such as mine (I don't have the budget to build a new structure). My garage will never be an airtight space & if I try to make it so, it seems I will be getting into other difficulties (one forum-member described witnessing plywood buckling on a roof becasue of the buil-up in heat from lack of ventilation). Given that, should I create a two leaf assembly, with airspace, INSIDE my garage? Until now (see plans below) I've been thinking that the second leaf would be the plywood / stucco walls of the garage itself, sealed as best I could. But I could make an inner room with two sheets of rock, insulation / airspace / insulation, two sheets rock. And then (I think) it becomes less critical what the isolating qualities of my garage are. If this plan seems sound (sorry for the awful pun), I would also, of course, need a ceiling of similar construction. The windows, with the agenda I'm describing, would consist of a Rod Gervais-style double window in the inner assembly. The windows in the garage itself that would let light into the space would be - it seems to me - less critical, as long as they had isolating qualities as good as the (remodeled) garage, with its new stucco siding. pdf's of the (old) plans are posted here: http://home.pacbell.net/needhame/clark.pdf

Your "plans" do not give enough detail. When I look at these drawings it looks like every time the door is opened, the "air" in between the mass air mass is walked directly into. That is what it looks like. And if that is what it is, then you are shooting yourself in the foot with this design. Any place that you have an opening breaches that aspect of the build and lessens the effectiveness. If you have a hole in your mass it has less ability to work as an overall component. Conversely, if you have a "hole" in your air, e.g. any path that leads out of this contained envelope and to the outside environment, it has less ability to work as it should. What you see as a wall and a door and an exterior wall I see as a boo-boo:) When the door is opened is there to be a ceiling overhead in this shelving/hall area...because you need one there or you are walking directly into the "air" of your mass/air/mass. When you walk into this hall from this exterior door if you can reach out to the left and touch insulation in your new build...you are most assuredly in the air of your mass/air/mass. If this is how it is...then you require a wall to make this part of your build more contained. You need that wall anyway to place the ceiling for the hallway/shelving area on, so it seems. And this has been what I have been after all along. Not windows, not sky lights, not roofs, not plywood...breaches. Your walls/envelopes, as best I can see from the detail in this sketch you have, are not >contiguous<. And this is far more important.

Thanks for a thoughtful critique. I will create more detailed drawings that include a ceiling in the shelving / hall area ...

...is there to be a ceiling overhead in this shelving/hall area...because you need one there or you are walking directly into the "air" of your mass/air/mass.

... and that seal in the air space of the interior room, so that you will be touching wall rather than insulation, as in the thought experiment you perform here:

When you walk into this hall from this exterior door if you can reach out to the left and touch insulation in your new build...you are most assuredly in the air of your mass/air/mass.

I had actually just arrived at the same conclusion by piecing together what others have told me. This means creating a room-within-a-room within a garage (as another Forum member just described it). But I think that's what I should do. Thanks, again.