Townhome Garage Conversion / Adding Layers vs Double Wall?

I'm in the process of converting a townhome garage into a small recording studio. This is primarily for my own bands use (rock band in the vein of Tom Petty, Wilco, Black Crowes), but I may be recording some other friends projects (no metal bands). My goals are to improve the isolation from my neighbors, reduce the little bit of street noise I have leaking through the garage door (Its a very quiet street, no trucks and very few cars) and eventually treat the room to improve the sound characteristics. Since this post can get pretty long and detailed, I'd like to just focus on the isolation aspects of the live room (re: garage) for this post. HOW IT LOOKS NOW: My garage is nearly 3/4 below grade and I am on an end unit. So basically, two of the four exterior walls have nothing on the other side other than gravel and dirt for at least 15 feet. :D My primary concerns are the garage door and a single wall that I share with a neighbor. The wall I share with my neighbor is constructed as follows (this is looking at the wall from my side): 5/8" Firecode Drywall > 2 x 4 studs with R-19 insulation in between the studs > 8" wide concrete block wall (goes from the foundation all the way up to my third floor) > and then on his side of the cinder block is 2 x 4 studs (no insulation) > 5/8 firecode drywall. I expect that the 2 x 4 stud walls (on my side and his) are touching the cinder block at random points. The garage door is a metal panel type (4 panels on hinges) that has 2" of insulation attached on the inside. I've been reading posts on here for several days now (and followed lots of links to other posts that take you to other posts and links that connect you to other websites... talk about overwhelming.... I feel a little like Alice in Wonderland: searching for an answer to a question just to find that I only stumbled onto new questions). So I figured I would post this and see if I can get some direct guidance/advice/help. I have some ideas of what I think will work, and have a fairly flexible budget (about 7-10k u.s.). But I don't want to throw money at a solution just to say I did something where I could have just thrown the money out the window and gotten the same results. Here are my ideas & questions that go along with them: WALL THAT I SHARE WITH MY NEIGHBOR: OPTION 1 - From what I have read, it seems my first option is to build another wall (in addition to the existing one) with an air gap between the new one and the old one. I would build it out of metal studs and can fasten two layers of 5/8 drywall to the new stud frame. I would keep a 1/8" gap around the perimiter of the drywall and fill it with acoustic caulk. My question in regards to that is how I can attach the new wall to the existing side walls, ceiling and concrete floor without compromising (shorting out) the isolation I am intending. Can the metal studs be screwed into the concrete and walls, or can I use (re: have to use) neoprene (or similar) bushings to decouple the new wall from the existing construction, without compromising the structural integrity? WALL THAT I SHARE WITH MY NEIGHBOR: OPTION 2 -My other options (I think.. once again, all this post following can be more than a bit mind numbing) is to attach resilent channel to the existing wall. Then attach two layers of drywall to that. From what I read, the resilient channel will get screwed into the studs of the existing wall and the channel will physically touch the existing drywall. Then I will screw two new layers of 5/8" drywall.. but I will screw new drywall to the resilient channel only. I'll leave a 1/8" gap around the wall perimiter and fill with acoustic caulk. What Im not totally sure of is if the resilient channel can be touching the existing drywall, and screwed directly into the existing studs. Once again, I don't want to just add another layer that is instantly shorting out and totally defeating my purpose. GARAGE DOOR: I realize my options here are very limited, so my expections of isolating a functional garage door are realistic; yet hopeful. My thinking was to screw or glue a layer of GAF TriPly 4 to the inside of the door. Then over that I was going to either green glue or screw (using rubber bushings?) some panels of sound board to each individual panel of the garage door (it has 4 horizontal panels). Then I was going to put a rubber strip in between each panel and on the outer perimiter. If you think any or all of that is a total waste of time, let me know.... I'll just make the garage door look nice from the inside and deal with my neighbors across the street when the time is right. Well, I think thats enough for now. :shock:I realize I have posted solutions for my own questions, but they really are more to let you know what my line of thinking is. If you think I should scrap any and all of them and try something else, I am all ears. Thanks!

Congrats on a nice intro to your project, RedWallStudio. :) Drawings or photos will be nice at some point, but for now, I think I can offer you this. Neither of your two options for addressing your common wall with your neighbor is ideal. While it seems you've got a good basic understanding of decoupling, you seem to be missing the overall mass-air-mass equation of a two leaf system. What you've described to me are either three or four systems. :( Ideal: lots of mass, followed by lots of air, followed by lots of mass. That's two leaf. Each mass is a leaf. Multiple layers of drywall without air between them constitute a single leaf. That's the bull's eye of the target. Sometimes you can't achieve that due to circumstances beyond your control, but you should strive for that whenever possible. The concrete block wall is one leaf. (This is true even if it's hollow... In the past there had been discussion of a hollow concrete block wall being considered two leaves, but that has since been dismissed.) The drywall on the neighbor's side is another leaf, even though there are most likely fusion points between those leaves. The drywall on your side is another leaf. That's three so far. One of your proposals calls for adding resilient channel (RC) to your side of the drywall and then adding more drywall to it. That would be four leaves with a very small amount of air between the two leaves closest to you. That's very bad. Don't underestimate the power of the "air" in the mass-air-mass equation. The other proposal of yours calls for erecting a new wall frame parallel to the existing one and adding drywall to the face of that frame. That's better, but you'd still have four leaves. :evil: You'd be better off removing all the drywall on your side of the garage and building a new frame several inches away from the existing concrete block wall. The larger the gap, the better. Leaving an 8 1/2" gap between inside edge of 3 1/2" framing will yield you 12" of gap from inner surface of drywall to concrete block wall. More is better, but the bang for your buck starts to drop off past 12". If you do that, you'd still have that third leaf on your neighbor's side to deal with. :roll: You're probably not going to have any influence on that. Perhaps ideal would be to have the neighbor's drywall and frame removed and the concrete block wall rendered with stucco to increase its mass and eliminate the third leaf... But I'm guessing that's not going to fly! :lol: You'll probably have to just accept that you have a third leaf and attempt to compensate for it by extra air and extra mass on your side. Consider a third layer of drywall on your new wall frame, or perhaps some Green Glue between the layers, or both. As for maintaining a functional garage door, all I can say, is YIKES. :roll: I honestly can't see any chance for that. :( I have yet to see a design for a functional sectional garage door in a studio where isolation is a high priority. Being in a townhouse, I'm thinking you may be under some restrictions that would govern the extent to which you can convert your garage to living space. I recommend you review the "Permits, Codes, Licenses -- and WHY YOU SHOULD CARE!" thread, and add to that verification that you don't have any [url=http://www.realtor.com/BASICS/condos/ccr.asp[covenants, conditions, and restrictions (CC&Rs)[/url] that would prohibit you from doing what you want to do. I hope that helps you get moving in the right direction... --Keith :mrgreen:

Awesome... thanks for the detailed reply Keith. :P You are right, there is absolutely nothing I can do about my neighbors side of the wall.. I think if I asked him If I could rip all the drywall off the inside of his garage, soundproofing would be the least of my concerns. :roll: And I appreciate and understand your building code concerns, as I share those as well. That is one of the reasons I need to keep the garage door functional. Finally, I can probably just rip the drywall off of my side of the wall I share with my neighbor, and then build the parallel wall. But, that sounds like Im basically taking my existing three leaf system and making it into a more efficient three leaf system by simply adding that air space. I know you said do not underestimate the power of air, but what should I realistically expect?... and would I be similarly well served by Green Gluing another layer of 5/8" drywall (or 2?) to the existing wall. If my difference in sound transmission is only going to be a handful of db's I would rather do something that I know will not violate code. I've recently found this whilst googling garage sound proofing. When a novice is on the internet, its hard to tell experts from novices that just play an expert on TV. :evil: http://www.soundproofing.org/infopages/garage.htm I like their idea of how to soundproof the garage door, and it was one I was thinking of (about 3/4 of the way down the page)... but if it ain't gonna work, its basically a space shuttle with a rubber band motor. :(

Aaaaaaaaaaaaaaaaaaaghhhhhhhhhhhhhhhhhhhhh! soundproofing.org!!!! :evil: :evil: DO NOT BELIEVE A WORD ON THEIR SITE. I don't have the energy to debunk the crap on their site today. :-( You get substantial benefit by increasing the distance between your leaves. Keep studying here to see more documentation and examples of that. Grab yourself a cup of coffee and get cozy with these documents:

• IR761: Gypsum Board Walls: Transmission Loss Data
• IR832: Sound Insulation of Load Bearing Shear Resistant Wood and Steel Stud Walls

Both of these reports are published by Canada's National Research Council, Institute for Research in Construction (NRC-IRC). Compare the graphs that demonstrate transmission loss. The higher the lines, the higher the soundproofing. Low frequencies are very difficult to soundproof, and those are the frequencies with the greatest improvement by increasing the depth of the gap between the leaves. Have you purchased Rod's book yet? ;-) Finally, you mentioned "handful of db" as though a small number of decibels doesn't make a difference. Depending on the frequency, a 6 db reduction is equivalent to a 50% perceived reduction in sound, and a 3 db reduction is distinctly recognizable... So don't be so quick to dismiss the power of "a handful of decibels." --Keith :mrgreen:

:oops: Well, at least it only took me 14 posts to figure out which site NOT to go to! Rods book is actually on my list. If its available at the Barnes & Knobles down the street, Im going to pick it up in 20 minutes. Otherwise I'll find it on-line. There is so much cross-over between isolation and treatment, and way too many experts. And I have to admit, I got stung by Foam by Mail too... which is why I don't want to learn the hard way any more. :D Okay, time to study.. and occassionally stare blankly at my garage door and shake my head. :cry:

Okay, I had to Order Rod's book, Barnes & Knobles didn't have any copies... should have it in a couple of weeks. :P In the meantime, I did download and read through the NRC pdf files that you gave to me. As painful as it was to have to print 57 pages out on my little inkjet printer, there was no way I was going to sit in front of my computer and read that. :shock: Wow, that is quite a bit of information and will definitely be a great resource while Im in this process, so thanks. I also found some great info on the green glue site. Its obvious I have to unlearn quite a bit that I took as simple logic before. Unfortunately though, there was no data from those NRC tests that I can use to apply to the wall I share with my neighbor. Yes, its a three leave wall, but the center leave is Cinder Block, which has a very significant effect on both airborne and structural transmission of sound. Is there anyone that has any experience, or anyone that has done any testing on situation similar to mine? Thanks! Michael

One thing you need to come to understand right away is that a wall system performs as a system, so while a concrete block wall may not be very good at stopping sound on its own, it can be quite good when it's a part of an overall system -- ideally two leaf, but in your case, probably three. I think by having a good heavy and thick multi-layered gypsum framed wall a foot or so away from the concrete block wall you share with your neighbor will perform very well. It's that garage door that's got me worried... So much so that I wonder if this thing may be finished before you even get started. :( Understand that if you have outstanding isolation on your ceiling and walls, but terrible isolation at the garage door, you will have terrible isolation, period. We sometimes call that the "weakest link" effect. You can plug four holes in your leaky bucket, but if you still have one hole left, you still have a leaky bucket. What's worse is that, contrary to logic, that bucket will leak about as much as it did before you plugged the other four holes. :( I consulted an acoustic engineer here in Sacramento when I was still in my design stage about a year and a half ago. He relayed a story of a drummer who built a soundproof room and did a really good job on his walls but he neglected his ceiling, and as a result he was sued by a neighbor. The engineer (who was not involved in the design of course) was an expert witness in his defense. He lost the case. The engineer told me he usually wins cases but he lost this one because of that darned ceiling not being addressed. Weakest link. It's real. Rod's book will be a great read for you. I'm sure you'll be posting your prasises on the "Rod's New Book" thread soon enough. ;-) --Keith :mrgreen:

another thought comes to mind as well. have you put a drummer and bass player in your garage and done some measurements? maybe have a couploe of hard hitting band members pop over and do some testing. talk to your neighbor and set up a time when you can get access to his place as well as yours (and the outdoors), get a decent sound level meter, and makes lots of notes while your friends play all out for 15-30 minutes or so. the reason for the drum and bass test is to allow you to find the problem areas rapidly. generally speaking the low end and low-mid will penetrate the walls and floors really easy whereas the guitar and upper range stuff will tend to be easier to isolate. you want to find all the areas where low end is getting through. for example, if your townhouse is over the garage, you might get some loss of isolation through your place and then into the neighbors place. it might not all be just the garage where you find sound coming through... listen to the garage floor in your neighbors place as well - have someone tap with a hammer and see if your garage spaces share the same slab (you can actually do this sooner than the drum and bass test). If they share the same slab it might be a problem. then again, after the drums and bass test, you might find that in the neighbors garage its Xdb loud, but in their home its hardly noticable. this may help in determining the level of effort you need to go through to keep your neighbor happy. once you have the sound levels mapped out and some drawings and photos, people should be able to assist more effectively.

Yeah, I think I need to worry less about the 8" thick cinder block wall and a bit more about the 1/16" thick metal door that separates me from my neighbors. :cry: Has anyone out there had any success with constructing a false wall in front of a garage door... that can be disassembled if the garage needs to be a garage again? Honestly, I don't have a problem making this be one step away from permanent, it just can't be permanently attached so Im not going against building code (if its not permanently attached, my village considers it "furnishings"). Basically it seems to boil down to four massive gobos that have a couple of layers of drywall on one side that can be attached to a mounting bracket and held in place. Its either that or building a smaller drum room inside my garage... but then Im back to converting a portion of my garage into living space.. which is a no-no. Ugh, why do I have to be the first to do everything? :?

I hate to burst ypur bubble, but it's not possible to do the kind of soundproofing you need in a manner that is not "permanent" and that would allow you to circumvent the municipal planning/permitting process. Go visit your local building department and find out what kind of garage improvements you're legally allowed to make sans permit, and I'm willing to bet it's limited to floor coatings and cabinetry. Also, typically noise abatement ordinances measure noise levels at property line, and inside the building if it is a multi-family dwelling. I'm almost certain that noise levels exceeding legal limits as measured in a neighbor's garage would be in violation. Look up the language of the noise ordinances in effect where you live, including your CC&Rs. You'll most likely find that your burden is greater, not less, than you thought. I hate being such a downer on this project -- I just want to be sure you don't spend lots of money, only to land yourself into a situation where you have neighborhood strife and/or legal problems because of faulty assumptions. --Keith :mrgreen:

First off, thanks Keith. You are not being a downer, you are being realistic considering the circumstances and have offered nothing but concrete (pun intended) advise. :D ...and Glenn, I think thats probably the best place to start. Since this is going to be primarily for my band, I think I need to bring my kit in and do some tests. BTW, one of my options (although not a favorite) is to do headphone practices, where the only "live" instrument is the drum kit and the vocals. Everyone wears headphones and the guitarists amps are in small iso boxes with a 57 feeding my console. That I have done before with good success, it just kinda gets old to have regular rehearsals that way. And yeah Keith, I'll find out what the deal is with both the noise ordinances and what I can do to my place without landing in civil court. In the meantime, looks like I finally get to use my Radio Shack sound meter! :P

Okay, nearly a month later... several chapters of Rods book (which should almost be a must read before even posting on here) have been read.. and I have decided to alter my plan. The first thing I did was contacted my village building inspector, who actually told me and I can do a lot more than I thought I could. Without going into a lot of detail, I only need a permit if I plan to do something that changes the structural integrity of my townhome, or messes with the electric or plumbing. While I may need to stretch things a bit with some minor electric (moving a few outlets here and there) I can build false walls and a room inside a room within my garage. After putting my Radio Shack SPL meter on my band at full volume, I've come to the conclusion that putting a whole rock band in my townhome garage and having any sort of "live rehearsal" is just unrealistic. But if I take the P.A. out of the equation and focus my efforts on isolating the drums and guitar amps and having my band get used to "headphone rehearsals", the possibility of making it happen becomes more realistic. Okay, so the first thing to tackle is the drum kit. Since it has no volume knob, this is where I need make sure things are done right. My plan is to build a drum iso booth in a corner of my 20 x 22 garage, or basically a 10 x 10 room inside a room. The inner drum room walls will be two layers of 5/8" drywall attached to 1 5/8" square steel studs (25 guage). On the two "square" sides, I'm going to install sliding patio style doors. A-this will allow visual communication for the drummer in both directions B- It allows for the lighting being used elsewhere in the garage to illuminate the drum room, thereby reducing the need for too much halogen lighting (heat!) in the room, and C - opening the doors periodically will allow the drummer to get some fresh air. The outer drum room walls on the "square sides" will have two additional sets of sliding patio style doors, the other "non square" sides of the drum room are the existing walls of my garage. This is where my questions come in. I've attached a pic to explain where I am at. Okay, my first question is the existing wall of my garage. In this picture that wall is to the right and below where my drum room is. I can strip the drywall off of that, which will expose the open cavity and thereby create a single leaf system. What I cannot do is apply any drywall to the opposite side of that leaf. That is my control room, and there is just too much stuff in there to create a mess, not to mention all the wood trim that exists in my home.... in short, it ain't coming out. So, my question is, can I apply a layer of drywall in between the studs and caulk around the perimiter, thereby creating a double layer of drywall.. but from the inside? Rods book describes this process in relationship to ceilings, but I don't see why this can't be done to walls as well. Yes? My second question comes to the dual pair of sliding glass doors. My design has them laid out so there will be a 1/2" gap between the doors(these are in bright yellow on the floor plan). My plan was to fill the gap with weather stripping, but after reading the section on doors in Rods book, he states that it is okay to break the rules and have double sets of doors connected by a common jamb. I just don't think its necessary with sliding doors, but I noticed that in the sample plans posted in the studio design section "Sample floor plan for Bedroom, Garages and Larger Rooms", it shows pairs of sliding glass doors being physically connected as well. Can someone clarify what would be proper? My last question (for the time being!) is in regards to air. The drum room will sit below a heat & a/c vent, which I could create a connection to feed the drum room with air. But obviously I this also creates a 4 x 10 hole where sound can escape. So, is there any type of "sound baffle" that can be created to allow air to flow in but not allow sound to get out? Wow, that sounds like a really stupid question in hindsight.. but I just have ask before I create a completely airtight room.. so pardon the brain fart! If it has to be air tight and thats it.. I'll just be happy Im not a drummer. Thanks in advance for all your help.. and I apologize for being long winded.. just want to be thorough. :wink:

A couple of comments: 1. First, I would highly recommend that you get to know your neighbours and give them an idea of what you'd like to do in your garage (i.e. approximate times of rehearsals, # of times per week, etc). If you get them involved at the design stage, then they're less likely to want to call the authorities on you. Also, this will give you an idea of what neightbour is most likely to be the one to call the city. At any rate, establishing good ties with the neighbours is probably the most cost effective thing you can do. 2. Your drummer will need both supply and return air....remember it's an air-tight structure and you can't rely on cracks and gaps to allow air to find its way back to your furnace/air con unit. Yes, you can put baffles in the HVAC..I built some and described em in another thread. I'm not sure how well they work, but the shouldn't hurt, and they don't impede airflow. 3. If you're going as far as having an isolated drum room and using headphones, why not just buy a set of V-drums, and not bother with the isolated drum room. It would probably cost about the same (if not cheaper) by the time you add the cost of mics/preamps to get the drums into the monitors of the other musicians, plus will offer way better communication that thru a window. 4. Is it possible to build a wall behind your garage door...i.e. retain the cosmetic front of the garage door, but behind it is a proper wall? Or, are you trying to keep this space useable as a garage? Cheers Kris

Thanks for the input :D 1.) Yes, Im planning on having "the talk" with my neighbors this week before I order any of my supplies. They all seem very nice, and have been pretty loud themselves at times (heard it outside, but not much inside my townhome), so I hope to keep things friendly. 2.) Okay, I'll search for the baffles. Can anyone point me to a link to them? 3.) The primary reason for my home studio is to record, so I would rather have a live acoustic drum kit. If this were just for band practice... yeah that is the way it would go. I also plan on recording other projects at some point, so V-drums are not the way to go. 4.) Yes, I am going to build a wall behind the garage door and keep the cosmetic door. Im going to tackle that project once the drum room is complete; need a way to get materials in for that first. Sharward, if you can offer any input into my design and my previous questions, it would be greatly appreciated. I am planning on ordering the materials I need this week for delivery early next week :shock: Thanks!

Here's the link to the baffles http://www.johnlsayers.com/phpBB2/viewtopic.php?t=8425 Not the greatest design, with more time and effort put into it you could probably come up with something better, but the overall principle is prett sound I think. Superduct, and/or ductliner is probably a better way to go...I highly recommend investigating it. Personally I've never liked the sound of small rooms, so I wouldn't opt for a small drum room, and would put more effort into trying to isolate the main room...but to each their own! just be aware that a 10X10 room will have some serious modal issues, and will need lots of acoustic treatment....don't forget to leave space for that. Also, be aware of the footprint of a drum set. Mark out the proposed dimensions on th floor (including the door), and see how easy/hard it is to put a kit in and out of the room is. Cheers Kris

Thats a good point about the size of the drum room, although I have seen other small rooms. Unfortunately, it would be nearly impossible for me to isolate the entire inside of the "main room". I would just have so much to contend with that the project would die before I could get it off the ground, so the smaller room is the only way I can go. I've done my best to make the room fit with proper acoustic design. I tipped two of the side walls in at 12 degrees so there is no ping-pong effect. I planned on keeping the floor a hard surface and the ceiling would be treated with absorption. My question is this though, is my drum room so small that I would just be better off not angling those two walls and make it be square.. and then treat those walls with absorption as well? No sense wasting the real estate if it isn't going to sound good. And if I wanted to have some "room sound" what would be a minimum size to go with before its pointless?

As far as minimum size for room sound...I think that you'd need on the order of 1500 cubic feet of room volume. I forget the exact number, but this is the minimum value suggested by the BBC for voice studios. Small rooms tend to sound small...no matter what their shape is. I've seen lots of small drum rooms in designs on this site, and I have the same concerns about all of them. After having had the displeasure of mixing in an 8X8X8 box, I just can't imagine getting a good drum sound out of a box that's not much bigger. If you're stuck with those dimensions, then I'd say yes, make it square (well, rectangular would actually be better from a modal perspective), and absorb heavily. Finally, how much isolation do you need for the drums? Please note that in your figure, where the angled walls meet the back wall you have your weakes point. these walls are drawn as sharing a stud, and have the minimum distance between the inner and outer shell. Also, where is your door??? Cheers, Kris

Okay, I think Im going to go back to Rods book.. do some more research and revise my design. Yeah, the room is pretty small. I'll see how I can get 1500 cubic feet of air... it may be possible. To answer your questions, there are two sets of sliding doors. They are on the drawing in Bright yellow and are on the top and left side of the floorplan. Yes, those two corners are very close to the existing "inner" garage walls, but Im going to strip the drywall off those leaving the open cavity. That should give me an additional 6" of air space in those two corner. I won't let any studs short out by touching. Thanks for all your help.. its immensely appreciated! :D

BTW, are you aware of the 'golden ratios' for rectangualr rooms (there's three of them)? These ratios will help balance the modal response of your room. Another thing to consider is that the longest dimension of your room defines the lowest frequency that has modal support...part of the reason why small rooms sound small is that there's no modal support for the low frequencies and instead there's a big clustering of modes in the mid band. Cheers, Kris