Plans for Rehearsal Space in Berkeley Garage: Feedback?

Posted: Wed Jun 04, 2008 2:01 pm

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: internal dimensions (see link to plans) are 11 and 15 foot-wide walls 21 feet apart, and an 8 foot ceiling. It's 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 providing a link to (just type the url in your browser), 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 welcoming all criticism. Foremost among my concerns are:

1) Am I getting into problems by having so much space between 3 of my internal 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.

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.

pdf's of the plans are posted here:

http://home.pacbell.net/needhame/clark.pdf

Posted: Wed Jun 04, 2008 7:58 pm

"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. " /quote

Ceiling joists look to be 24" + on center. Did you get any recommendation to install additional joists so as to have an acceptable layout or no?

Posted: Thu Jun 05, 2008 8:46 am

Space wrote:

"Did you get any recommendation to install additional joists so as to have an acceptable layout or no?

Thanks for your note.

I have a recommendation to tie the ceiling structure together at the gables with metal braces, for seismic reasons. I'll be doing this. However - if I didn't make this clear - the roof will not be supporting the ceiling of the inside assembly. It's not intended to. The ceiling of the inside assembly will rest on the inside walls, which will be built with heavy-gauge metal studs.

When I refer to reinforcement of the ceiling, I am talking about metal that will be installed perpendicular to the joists in the ceiling (which is not built yet - it doesn't exist), not joists in the roof.

I hope that's clear. The joists in the roof (pictured) have nothing to do with the joists and bracing in the ceiling we'll be building.

I'm especially interested in recommendations for my windows. The Green Glue website talks about varying opinions as to the best way to get isolation. I'm looking for specific recommendations for an application like mine: Because this is a rehearsal & practice space rather than a recording studio, I am trying to let some sunshine in instead of sealing it up: So I've got this 2 - window issue arising from my room-within-a-room design.

How best to get isolation with those 2 windows, one after another, each installed in its own wall? Double-pane windows for both? If so, what thickness of glass & what type?

I read that laminate glass when it gets cold loses its superior ability as far as (stopping) transmission of sounds, so I am assuming my outer window assembly should not be laminate.

Posted: Thu Jun 05, 2008 9:26 pm

I see. So maybe you could explain what it is you guys are doing when you say "caulking plywood in the roof"? This is foreign even to someone as far out as I Smile

Will your roof be the weakest link? It's going to depend on what you do with that door in the exterior wall that breaches the room in room design. Or maybe another wall would help? I'd opt for a skylight and just be done with all the speculation.

Posted: Fri Jun 06, 2008 12:51 am

Space wrote:

I see. So maybe you could explain what it is you guys are doing when you say "caulking plywood in the roof"? This is foreign even to someone as far out as I Smile

Will your roof be the weakest link? It's going to depend on what you do with that door in the exterior wall that breaches the room in room design. Or maybe another wall would help? I'd opt for a skylight and just be done with all the speculation.

1) What caulking is for: The existing plywood that comprises the roof has had several generations of roofing nailed into it, and was not brilliantly built to begin with. I've been advised to get in there & seal anything that comprises a chip or a nail-hole. Acoustical caulk is what I've been told to use, but, hey, I'm new to all this. I'm hoping with the advice of wiser minds and my fairly savvy contractor, we will button things up as they should be.

2) The doors will be built according to specs from Rod Gervais' book & I hope will not compromise things too much. Regrettably, one does have have to get in & out (don't mean to be sarcastic: It has occurred to me more than once that things'd be easier if I could just seal myself in, like some Edgar Allen Poe story).

3) I'm not sure I get the advice for another wall, but I'm all ears. Wouldn't this create a four-leaf assembly? It had occurred to me to put sheetrock up against the inside of the roof to help with what I am guessing is my weakest link, but that runs against everything I've been reading & hearing. The mass should be on the outside, yes? And other than laying down more roofing, I don't know how to get the mass there.

In connection with this ... do you know what sort of isolation I can expect with comp shingles + 1/2 " plywood + insulation? I'm asking because - unless I plan for a skylight, as you mention - I am figuring what thickness / type of glass i should use in my external window. I'd like to know what sort of isolation I should expect from the roof, so I can make a good call there. Don't want to break the bank on an external window that is more massive than necessary.

4) Your skylight idea: I guess I should go read some posts about skylights. Is there a reason this would be simpler to engineer, or less troublesome as far as escaping noise. Is it an advantage that any sound that is escaping is escaping roofward rather than laterally, as it would through a window? Again, I'm all ears.

Appreciate the help very much !

Posted: Sun Jun 08, 2008 3:53 am

Space wrote:

I see. So maybe you could explain what it is you guys are doing when you say "caulking plywood in the roof"? This is foreign even to someone as far out as I Smile

Will your roof be the weakest link? It's going to depend on what you do with that door in the exterior wall that breaches the room in room design. Or maybe another wall would help? I'd opt for a skylight and just be done with all the speculation.

Space, please accept my apologies for any offense or confusion created in these forums. I may have created both. Mia culpa.

I am curious how you would prepare the eaves (pictured in pdf's) before putting insulation in place. Advice that I got from a friend who's been through a similar project was to use acoustic caulking. What I take this to mean is caulking seams: The areas that air could move through (even though comp shingles are in place). Would you simply putty & paint to seal nail-holes & chips?

Posted: Thu Jun 12, 2008 7:23 pm

No offense...some confusion Wink

Some things you will see in yours or anothers building are there for a reason and shouldn't be modified.

With your roof, or mine, it is the overhang(if built with one) that provides the air flow from the bottom of the roof system that helps to move air out the end of gable vents, ridge vents or roof vents/turbines.

The roofing plywood can shrink and grow because of the changing temperatures. It does this all year long. So, as a rule, builders make certain that a building has adequate air flow in the attic to maintain the structure.

I witnessed a place that folks had limited the airflow and the plywood was buckling off of the roof! The heat built up over a period of summer months with limited means to escape and basically fried the plywood/shingles. The inside of their building was hotter as well with heat coming in through the ceiling as well.

As to what I would do. If this is an existing structure I wouldn't do anything to the roof. Some things are what they are and attempts to improve them return very little if anything at all.

Posted: Sat Jun 14, 2008 10:50 am

RE: My "outer room," I see the logic of accepting that my garage will never be an airtight space & if I try to make it so, I will be getting into other difficulties.

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.

pdf's of the plans are posted here:

http://home.pacbell.net/needhame/clark.pdf

Posted: Sat Jun 14, 2008 11:22 am

So... Let me get this straight. You're going to build a room within a room within a shed?
How big is your shed?

Posted: Sat Jun 14, 2008 12:08 pm

Garage dimensions: 21 x 24 feet (it's a 2-car garage)

Joists allow for eight foot ceilings after construction, though if this new plan is a contender I'm going to lose some inches on the ceiling height.

Other than the ceiling height issue & the ambition (cost & time) involved, is this really such a bad idea ? It gets around the seeming impossibility of turning a garage into a space that will hold sound.

Posted: Sat Jun 14, 2008 6:40 pm

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.

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