AT's Studio in the Garage

Almost ready to start the construction on my garage studio … where the space is very limited. I already have an L shaped 2 existing walls which will be enclosed to build the studio in. Planning on floating the floors and the walls but these existing 2x4 walls are already fastened to the concrete slab. I know that room in a room (double wall with air gap) is the best way around this problem but as you can see this space is very small and I don’t want to loose any more real estate space. My (naïve) idea is to float the newly built floor and the walls (shown in pink) and leave the existing walls as they are filling all the cavities with Rockwool, RC and layers of drywall. Nevertheless floated walls will be attached to the existing (non floating) walls along with ceiling joists. Would this create a problem? Would I be better off fastening rest of the (newly built) walls to the concrete... floating the floor only? FYI: Tracking and the vocal booth will have double walls between them and all the rest will be single walls… all with RC. Construction has started, go to page 4

Having some walls floated and some not isn't practical; kinda like having half your houseboat on pontoons and the other half anchored in concrete when the tide comes in... You've only stated about 1/8 of the info requested in the "dont even think about it" post at the top of the forum; if you can read through that and add to your information ALL the points covered (to the best of your knowledge) it will help us help you. As a general rule, if you can't float the walls the floor is a waste of time to do, especially on a tight budget; floating a floor the WRONG way can actually make things WORSE. Please fill us in more http://www.johnlsayers.com/phpBB2/viewtopic.php?t=3231 and we'll see what can be done... Steve

Hey Steve, I kind of had doubts about partial floating of the walls, thanks for clarifying it. “houseboat” example is a good one :) Here is some more info and pix on what I’m trying to do, I’m located in a California suburban area in between San Francisco and San Jose. My house is in a relatively quite neighborhood; there is some traffic noise from a busy street 2 blocks down. There are quite neighbors about 25 feet away on each side of my house (patio side and driveway side). The types of projects I do are mainly keyboard, sample based Electronica/Dance and acoustic world music. There will not be full drum set recordings but a lot of ethnic hand drums/percussions. Plus a whole lot of vocal and acoustic instrument recordings. The tracking room must be whisper quiet from external noise. For the CR I’m not too worried about the external noise coming in but don’t want to bother my neighbors too much either. The 20’x20’ garage space which I will be building the studio in is attached to the house and has a concrete slab floors with a standard shingle roof. Roof joists are in the open and are not insulated. Roof starts at 10’ high and spayed up to 15’ in the middle of the garage. I will be using a little over half of the garage space to build this studio. 10’. 6” wide and 19’. 6”. long The roll up garage door will stay in place and will function. I already had the garage door track guides raised up for more headroom. The headroom for the CR section is 10’ (from floor up to roof joists) and for the voc/guitar booth is about 8’. 6” (from floor up to garage door opener). The whole space is 19’. 6”x10’. 6” I’m trying to gain a little extra space by integrating two existing walls into my design, as double wall system would shrink the whole space dramatically. My plan so far is to anchor all walls directly to the existing concrete structure and build a floating floor within it. All cavities would be filled with rock wool, RC and two sheetrock walls on the inside. Have been doing a whole bunch of reading here and I know that my weakest link in this plan is attaching the new structure to the existing one. Is there any other way to make this project work? Any comments or ideas? Hope the new drawing and the pix give a better idea of what I’m trying to do. Thanks for all the help

Here are some real pix

The tracking room must be whisper quite from external noise This statement can be very difficult to accomplish, depending on the noises you mentioned - it's hard to get good isolation without double framed walls and air lock doors and floated floors, if you really mean "whisper" quiet - the lack of extra space for thicker walls may mean some compromises. For normal mid-range noise, the RC will help several dB - for lows, not so. Only mass and distance (filled with insulation) will take care of the lows. Do you have a tentative budget yet? Planning on pulling permits? These are just a few of the points we'll need to cover... Steve

Hey Steve, Have already taken care of the permit issues. The budget is about $8000 plus labor. A carpenter friend of mine will be working along with me. He has some general idea about acoustic buildings and has also been doing some reading here on the forum.

Hi Alex, I can't help but notice many similarities between your project and mine. Although you're designing a recording environment and I'm designing a rehearsal environment, many of our requirements and constraints are the same or very similar -- square footage, high soundproofing requirements, budget, etc. If you haven't already done so, I recommend that you read through my now 7-page thread so that you can benefit from my experience. You'll see that the plan has changed a lot since the initial posts, and as of the time of this writing, it's in somewhat of a state of limbo, largely due to some unexpected obstacles that you might well run into. I'm also kind of curious about this:

AlexT wrote:

Have already taken care of the permit issues.

How were you able to secure your permit without plans? And if you had plans in hand when you got your permit, and you're still in the midst of finalizing how you will proceed with the build, then doesn't that constitute a material change in the plans that would invalidate your permit? --Keith

sharward wrote:

How were you able to secure your permit without plans?

Hey Keith, I have a permission to expand my garage space (since I have already built a separate 2 car garage detached to my house) but will still have to present my final plans for the permits. Have been following your thread and learned quite a bit from it. Hey Steve, Maybe I overstated by using the term “whisper quiet” for the tracking room. Perhaps as quiet as I can get given the limitations of the space… would be a better way to put it. It is a 19.6 x 10.6 feet space to fit a small voc booth and a workable CR. Initially my plan was to do the whole double wall, air lock thing but that makes the space real tiny. Have also thought about the “inside out” wall design floated inside the outer shell? This will be a little more space saving method but is it worthy? "the lack of extra space for thicker walls may mean some compromises" I’m ready to do some compromises as long as I have a decent enough isolation to not bug my neighbors too much. :? Thanks everyone for your help

Alex, looks like I missed a few here; Initially my plan was to do the whole double wall, air lock thing but that makes the space real tiny. Have also thought about the “inside out” wall design floated inside the outer shell? This will be a little more space saving method but is it worthy? This can get tricky to recommend, not being there in person - the "tiny space" vs. "usable space" can be a real conundrum. If you build for maximum usable space, then it's very possible that NONE of the space will be usable except when everyone else is at work or gone. If, on the other hand, you build for max isolation to the point where your instruments and you won't fit inside the space at the same time, well :cry: As to "inside out walls" - these are not a "magic bullet" - your isolation is still determined by the amount of mass in each of two leaves, combined with the depth of air space/insulation BETWEEN those two masses. The only thing "inside out" construction buys you that's actually FREE, is one less set of framing lumber in order to hold acoustic treatments on the INSIDE of the INNER walls, since this framing is the same lumber that's holding the wall panels. I'm not saying this isn't important, just that isolation won't change without the air gap or mass changing; it's irrelevant where the frames go as far as isolation is concerned. Before you spend a lot of time or money on deciding how well you need to build, it would be a good idea to get a SLM (the Radio shack ones are reasonable and work fairly well) and I can tell you how to test to see how much MORE isolation you need... Steve

Thanks Steve, I got a SLM (Radio Shack, the digital version) Don’t know if there is a certain technique to using this… but (going by the manual) the overall readings I get are around 52db when the garage door is closed and between 54-64db when the door is open (on busy traffic hours). I have settled on the idea of floating my new walls. Nevertheless, given the space limitations I can’t have double walls on all sides (see the new drawing). What do you think? I’m just worried about tight room dimensions. Will only have 10x8.6 ft space in the CR after applying acoustic treatment (not counting in slots and corner traps). Don’t use large mixing boards but have a lot of outboard gear to put in that small space… :?

if you've got two room that don't touch each other, you don't really need the RC.

Sorry, no time to get into this til tomorrow (off to work) - I resized your pic so it doesn't make us scroll sideways to read the text; this affects the entire thread, so please keep pix down to around 750 pixels wide - Also, long links will do the same thing; here's the way to do long links without them causing the problem. [url=LINK]TextYouActuallySee[/url] If you copy the above to a text file, you can just cut and paste - LINK is your entire link, starting with http.... then close the brackets as shown, type whatever you want us to see as a link where it says TextYouActuallySee, then do the [/url] at the end. Until I set this up as a separate file to cut and paste from, I only got this right about half the time, hope it helps others... Steve

knightfly wrote:

Sorry, no time to get into this til tomorrow (off to work)

OK Steve, Looking forward for more inputs. …and sorry for the pic size.

Alex, before I can say one way or the other about your plan I need a more detailed description/sketch of your proposed (and existing) wall construction, starting at the outside and moving through the wall(s) until you're inside the rooms - layer by layer, including any air or insulation, frames, layers, etc... I think you're making it more complex than it needs to be, but I won't know til I see your exact construction as above. Hint- your garage door obviously sucks as a sound containment device (note your SLM readings with door open/closed) - so that door can't be considered either of your two Leaves of mass in a mass-air-mass system - Hint- if your outer existing walls already have wallboard on their INSIDE, you will need to REMOVE it (possibly using it for an increased mass in conjunction with your outside siding (need to know what THAT is made of also) Give me details, the more the merrier; and I'll try to give you a way to keep as much space as possible and still be happy with your space... Steve

knightfly wrote:

...Give me details, the more the merrier; and I'll try to give you a way to keep as much space as possible and still be happy with your space... Steve

Thanks Steve, Here is a clear sketch of all wall layers (both existing and new). Please note the CR and the Vocal Booth floor/walls will be floated separately with air gap in between (see previous sketch). Here are the ceiling layers since you can’t see it in the sketch: Inside to out: 2 layers of wallboard RC 2x4 cavities filled with rockwool 3/4” plywood and 3/4” MDF on the very top. You’re right about the garage door not being a sound containment device; it is not taken into calculation as a leaf or mass. Existing walls do have wallboard on the inside and they will be removed and filled with rockwool. Hope these details give you a better picture of my space and thanks for all the help.

Overall that looks really good; except that since the inner room is floated, there is no need for RC - also, since you're removing existing wallboard if you're careful and remove it carefully with a razor knife, you can re-use the sections as "inserts" between studs (fastened in place with cleats holding it against the outer wallboard layer) - this will improve wall performance by a few dB by increasing the mass of the outer leaf. Caulk edges completely before insulating. If you do a search on "gypsum insert" the first 2-3 posts have info that's more explanatory... Steve

Thanks Steve, All your tips have become a part of the project. Demolition has started on existing walls and will start posting pics soon. I have another question, did some search but couldn’t really find an answer. Two walls of this design are double walls and the other two are single walls with sheetrock on both sides (partial garage conversion). Control and the Tracking rooms will be floating separately. The thing I haven’t really figured out is how to seal the cavities marked A, B and C in the sketch? These cavities need to be sealed both from the SIDES and the ceiling TOP. What would be the right way to do this without hard surfaces touching each other thus causing flanking? I thought about stuffing these cavities first with Rockwool toped with Neoprene of some sort but not sure if that is the right way... Alex

Alex, I've been trying to find time to redraw your setup; there are a few things really WRONG with it, so please have patience while I work on a couple ideas. Demolition is fine, but don't put anything BACK just yet... Steve

knightfly wrote:

Alex, I've been trying to find time to redraw your setup; there are a few things really WRONG with it, so please have patience while I work on a couple ideas... Steve

Thanks for letting me know Steve. Only took off the sheetrock on two existing walls. No new construction yet. Looking forward to hearing from you. Alex

OK, few things I need to know - obviously this is older construction, by the fact that your roof is separate boards, the roof framing is stick built (marginally), but the garage door is new(er) - First thing - Are you up for some framing mods to the roof if necessary, such as adding collar ties to ALL your rafters instead of every third one, and adding a couple of new chords to each rafter/collar tie to form trusses? (This isn't dangerous, just takes a bit of effort) Second - what is the actual height from the floor to the garage door track, where the track is level? Where I'm going with this - your existing + ideas won't give you a good mass-air-mass envelope around the entire space; I'm trying to make it so you can do that with minimal loss of interior space... Steve

Hey Steve, You’re right the building is old and the garage door is about 3 years old. I already had the garage door tracks raised up to gain more headroom for the studio. Are you up for some framing mods to the roof if necessary? I am ok with framing mods to the roof (hope it is not a major work :) ). The actual height from the floor to the garage door track is 8’ 10” and from the floor to the roof joists is 10’.

I'm trying to make it so you can do that with minimal loss of interior space... Steve

That is exactly what I need. Thanks for all your help.

Forgot to ask more about your intended floating floor details; can you do a sketch showing each component, and include ceiling framing you intend? I'm assumiing you mean to build new ceiling frames UNDER the garage door track - what I'm NOT clear on is what you intend for an OUTER leaf, as far as ceiling and roof are concerned. The door track gets in the way for most solutions to this... Steve

OK Steve, Here is a better sketch looking from the side. You’re right about the door track and my solution to it is by spaying the ceiling of the Tracking Room down towards the garage door as seen in the sketch. I don’t know if that would be a good thing to do… :? Hope the drawing helps. Thanks, Alex

Still haven't gotten enough time to finish what I started, but a couple of things re the last drawing - your floated floors won't stop very low frequency with that amount of mass and space, I'll need to calculate what their resonance would be, at which point they will actually AMPLIFY instead of isolate. 2x4's, even on 12" centers, won't span your short dimension with that much hanging on them. 1.5" of sheet rock is just over 5 psf, 1" MDF is about 4.25 psf, and since dead load includes framing members, the weight of the joists will add another pound at least; this means designing at least for 10# dead load. If you want more than 1" MDF on top, 2x6's on 16" centers would be necessary. This would also improve TL with the additional 2" air gap, and the sheet rock would need to be hung on resilient mounts of some sort since the MDF would be your outer leaf, and would need to be isolated from the inner one. For sanity's sake, I'd use three layers of 5/8 instead of two layers of 3/4; even 5/8 gets heavy when it's overhead... Steve