Design for my long one-car garage

Hi— I'm humbled to be posting here, especially since my math skills leave much to be desired, but hopefully I've learned enough to communicate. I hope you’ve had some caffeine. I think I kind of wrote a lot…. My name is Mark, and I live in Seattle, WA. I’m going to build a studio in my one-car garage, which I’ve enlarged as much as my property and local building codes allow. Originally, it measured 11’ 3” by 18’ (outside dimensions). I’ve added on to the front of the building so that it now measures roughly 11’ 3” by 30.’ I wish I could make it wider, but that just wasn’t feasible. The inside dimensions (framing to framing) are 10’ 5 ½” (w) x 29’ 4 ½” (l) x 8’7” (h). I posted a brief thread on the construction forum awhile back and got some help from xSpace on some outer leaf questions. Since then I’ve just been focusing on the actual design for the studio. I’ve spent many months and countless hours on this site and in Rod’s book, trying to learn as much as I can so that I can ask some intelligent questions. Thank you so much for this resource, John and everyone else! I’ve already learned a ton, and I know I will learn much more before I’m done. My hopes for this space are to play with small groups of musicians (3-4, including myself) and to be able to record live drums. More specifically, I'd like to be able to record rock music in there without being visited by the police. I’ve spent a lot of time trying to make a design for separate tracking and control rooms in Sketchup, but I’ve come to the realization that, acoustically, this is just not very realistic for the small space I have to work with: either I can have a decent-sized control room and a tiny tracking space, or vice-versa. However, I’m working on a possible compromise that I’ll describe in a moment. The floor is concrete slab on grade, although it's 100 years old in the existing section, and I doubt it's very thick. I’ve decided after reading a lot of the posts on this site that I won’t float the floor. I may, however, install a Dricore sub floor system, like Greg did on his build: viewtopic.php?f=2&t=11485&start=90 …caulking around the perimeter as I go, and build my inner leaf walls on top of that. Isolation will be quite important; my neighbors’ house is only about 12’ from the garage, and they have three young kids. On that topic, here is what I’ve done so far to the building: Once the new addition was built, I tore off the original siding and installed a new layer of Densglass sheathing on the entire exterior. Because of the proximity to the property line, I was required by building (fire) code to use Densglass on the wall facing my neighbors. I decided that the garage was small enough that I could afford to do that all the way around, giving another 5/8” layer of mass on my outer leaf, caulking the seams with acoustic caulk as I went. I plan to add another layer of drywall on the inside, between the studs up against the outer leaf, as well. The new addition has 2x6 ceiling joists, and I will be replacing the 2x4’s in the existing structure with 2x6’s, as well. From this, I will hang 2 layers of 5/8” drywall for my outer leaf. I realize that once I build my inner leaf structure that the roof will act as a third leaf, but I don’t see any alternative to this: the roof area needs to remain open in order to ventilate. I haven’t really come up with a budget. I’m really trying to do this as well as I can to get the best isolation possible. I may decide at the finishing stage to save money on those materials, but the “beef-up” stage will be very important. If, in the end, I still feel that acoustic drums are too noisy, I’ll have to settle for electronic ones, although I really don’t want to do that. I just picked up the sound level meter that Rod recommends in his book; I’ll take some readings with that to get a baseline for what’s feasible. Budget-wise, I’m doing all the work myself (used to be a carpenter), so I’m saving there. Still going through the “can I afford Green Glue?” debate in my head. I’ll probably end up biting the bullet on that one. So….on to my design ideas so far: I’ll be replacing the roll-up garage door with old carriage doors that I resurrected. They’ll look better, and I won’t have the whole overhead track issue. I do need to keep the first five feet for storage of yard stuff, tools, etc. I’d love to build a separate shed for this stuff, but we just don’t have the space on our property. I will be beefing up these doors, although I haven’t settled on the specifics yet. I’ll probably do something along the lines of what Rod provides in his door designs. I plan to install a 2’6” door going into the inner space from the storage area. This will be beefed up, as well. This leaves me with 10’ 5 ½” (w) x 24’ 4 ½” (l) x 8’ 7” (h) for the interior dimensions. Depending on final decisions about how to build my inner walls, the width (and all my room calculations) might change slightly, but for now, I think these dimensions are a good starting point. For my inner leaf, this is where I’m at so far: I’m planning to do inside-out walls all the way around, with two layers of 5/8” drywall. Question: Does that make sense for this shape? I figure I can add treatment in order to liven up the room as necessary, but maybe it makes sense to just build the walls in the normal way and add absorption to the side walls (?) I need to make this decision before I can really do proper calculations for room dimensions. For the sake of the conversation right now, I’ll plan to build them inside-out, and adjust my dimensions if I change my mind. I’ve tried angling the side walls 6 degrees for 6 ½ feet from the front of the room to help make a reflection-free zone. This is shown in version one of the plan. These will be treated with slats. I tried to do more of an angle, but the narrow width of the room made that difficult when it came time for the soffits. The problem with this version is that the listening position would probably lie right about where the angle begins. Probably not going to give me much benefit in terms of an RFZ. Version two of the plan has these angled walls going out further, extending the RFZ, which is probably better. However, in this plan, the distance between the soffits is pretty small. I’m not sure if that’s good,either. Question: Perhaps my space is too narrow to angle the walls? Or does one of these versions look ok? I suppose a compromise to the inside-out issue would be to build this front area inside-out and the rest of it normally. For figuring out the proper dimensions for the room, I’m using my width as the critical dimension (I don’t want to lose any width), and trying to size the height and length to create a good room ratio. For my calculations, I’m measuring drywall-to-drywall (assuming the walls will be inside out, this is correct, yes?). My width with inside-out walls is 10’3 1/2.” Here’s where I get to the compromise I mentioned earlier: I’m working on designing a moveable wall in three sections. The two outer sections would be framed in 2x6 with one or two layers of mdf running down the center. The mdf would be covered on both sides with 2” of 703 or something like it. The center section would essentially be a typical insulated glass door, with the doorjamb framed in 2x4, which would rest against 1 ½ x 2” stops attached to the inner frame of the outer sections. All three sections would have wheels on the bottom (like they do with an Ampeg 8x10 speaker cabinet) to facilitate moving around the room. Isolation-wise, I think the door would be my weak link, which might affect whether I decide to do one or two layers of mdf in the other sections. I would build them in such a way so that there was a gasket all the way around, to help with isolation, as well as a solid section of wall on the inner leaf for it to rest against. While I know this would be nowhere near as good as a double wall, it would give me some flexibility with back wall placement in the CR. The wall could be closer to the desk when tracking drums, for instance, and farther back when mixing. You can see by the Sketchup design that I’ve put large traps in the back corners of the room. I suppose these could be made moveable, similar to dynamike’s: viewtopic.php?f=2&t=8205&start=60 so that I could use them when mixing, as well. The two side sections could also be stored diagonally up against the bass traps on the back wall when not in use. I know this would be a lot of work for less-than-ideal results, but I really like to hear what things sound like through the monitors rather than through headphones as I’m recording. I suppose I could also configure these to make a vocal booth, as well. Question: does this seem dumb, or do you think it could be worth doing? I’m confident in my carpentry/design skills that I could build this in a way to make it safe and relatively easy to move around. Assuming that the above wall idea is workable, this is where I get back to my room dimensions. If I take a 96” ceiling height (ceiling not built inside-out—I was planning to use clouds) and my 123.5” width, and I put the move-able wall at 182,” I’m at Louden’s 2nd room ratio. With an 88” ceiling height, my 123.5” width, and placing the back wall at 167,” I’m at Louden’s 1st room ratio, although then I’m losing quite a bit of height at that point. I’m planning to soffit-mount my monitors (Alesis M-1’s). I’ve angled the soffits 30 degrees, which gives me a space between the soffits that’s 37” wide and 6.5” deep in version one of the plan. I could fill this space with insulation (I'm under the impression that that can help focus my stereo image[?]), or I could just let the soffits run into the front wall, but I think Knightfly said something about a “horn effect” with this sort of placement, so I’m not sure what to do here. Question: When I trace the equilateral triangle for my listening position in version one, it’s a challenge to get me 38% back from the front wall. I think it can be done if I tweak the monitor positioning within the soffits and use Louden’s 2nd ratio for the room, but I’m not totally confident on what I’ve done so far with the soffits. I guess I’m hoping someone can guide me on this. I am planning to use the room calculators available here to the best of my ability, but until I zone in on the proper thinking for my room ratio, I don’t know if they’ll help me much. Version two works better in this respect, and when I plug the numbers into Thomas Barefoot’s Wall Bounce Calculator, it looks pretty good (I think, but what do I know?) I did not plug in any absorption coefficients, because I think I need some more guidance on what a good treatment would be in this space. I’m sure there are many questions that I didn’t think to ask, but I hope I’ve provided enough information to get the ball rolling. Thank you in advance for any guidance you all can offer! P.S.: I tried to reduce the size of my Sketchup designs so that I could attach them: Window/Model Info/Statistics/purge unused, but it didn't seem to work. Am I missing a step?

probably one of your components is a large file - the garge door??/ check out this studio layout. http://www.johnlsayers.com/Pages/Flying_Fox.htm

Thank you, John. Tried deleting the doors completely from the file and that didn't work. I'll keep playing with it. Also, thank you for the design idea. I have seen that one, and that is basically the approach that I was trying to use before I came up with versions 2 and 3. My problem is that I think it will be very cramped in there with a few musicians playing (I know it will be cramped no matter what, but still...) I thought that if I was able to make this moving wall work I could have the best of both worlds: decent room ratios when mixing, and a bit larger tracking room when recording or just jamming. However, I will keep exploring the two room option, as well. When I have something worth posting, I'll do so.

Just a little more info...I did a few meter readings this morning. I would say that my average mix level is probably around 82 db, C weighting. Occasionally, I'll turn it up a bit so that I can "feel" it more, maybe up to 90db, but I try to keep it at a reasonable level. As far as the acoustic drums go, I took readings with a drummer friend of mine who I would say is about "average" in terms of how hard he hits, and he peaked around 110 db, although most of the time he was more in the 102-105 range. Outside, the ambient reading around 10:00 a.m. was about 65db. Inside, it dropped maybe 8db. However, I am not even close to being finished with the outer leaf (there's still just 1/2" plywood screwed over the 8' x 7' door opening, thin glass windows, no ceiling, etc. etc.). I would love a transmission loss in the neighborhood of 40 db in the lower frequency range. I'm hoping that's attainable with the construction that I have in mind, but I'm not sure.... I'm going to work some more today on the two-room design, spurred on by John, but I still have concerns about final dimensions. I really just want a space in the end that sounds as good as it can but is still somewhat comfortable to work in. Thanks, Mark

Hello again-- So, I've been working again on a two-room design, which I'm still not sure about. I played around quite a bit a while back, inspired by John's "Small Studio in 3-D": http://www.johnlsayers.com/phpBB2/viewt ... f=1&t=5457 In other words, orienting the CR sideways, next to the LR. Given the dimensions I have to work with, however, I finally decided that my building is too narrow to execute this design very well: the control room would not be long enough front to back. So in the last few days, I've been working on the the design attached below. The first change I made from version 2 and 3 is that I narrowed my "garden storage area" located behind the carriage doors down to 3' wide. This will force me to build an additional small shed to make up for the storage lost, but if this is a better design, then so be it. Doing this gives me an additional 2' in length to work with, which I will sorely need if I abandon my "moving wall" idea. The design would still be entirely inside-out walls with two layers of 5/8" drywall. I'm still leaning towards building the ceiling normally, using clouds for treatment, but I guess I'm still up in the air about that. All the yellow areas would be treated with insulation. I would still have slot resonators angled at 6 degrees extending past my listening position, with 30 degree soffits in front. The bass trap behind and to the right of the listening position would be moveable, so that I could keep the existing door to the outside in its present location (the other two plans call for just eliminating that door). The wall area between the bass traps and the slots would be cloth-covered inside-out walls. I'm hoping I'm not overdoing it with absorption in this room; my thinking is that the glass door to the LR, the top part of the soffits (tan area), and the slats will keep things lively enough. I know that a room of this small size will need a lot of treatment, hence my decision to build inside-out (no room to spare). The CR room ratio with this design is 1:1.27:1.52, close to Sepmeyer's 2nd. (95"0 ceiling height) My biggest concern here is that the listening position is almost exactly 1/2 way between the front and back walls. I really don't want to make the CR any longer, because I'm already afraid that the LR is going to feel too cramped as it is. Question: Is this one of those things that I can just deal with, or should I just go back to the one room layout? The live room is inside out as well, with bass traps in three of the corners, and resonators on one wall. I only angled these at 6 degrees, because I didn't want to eat up too much room. Hopefully this is enough to cut down on reflections while still giving the room some life. I've actually begun to wonder, though, if I might be better off in terms of TL by not building the live room inside-out. This would increase my "spring" in the MSM by 3 1/2". I know this would mean losing space to treatment, but perhaps the trade-off would be worthwhile. I still haven't abandoned the one room idea with movable partition wall, mainly because I like the idea of being able to fit more musicians in the room to just play music sometimes. I will refine versions 2 and 3 with more wall treatments, to flesh out the designs more, but I'm really hoping for a little feedback. Is there something I'm not doing that I should be doing in order to get more responses? I'm trying to do as much work that I can think of on my own. Any guidance will be very appreciated! Thank you! Mark

Are you going to follow the roof line of the outer leaf in your live room?

Hi! No, unfortunately, the building would have to be re-engineered for that to work, and that would blow my budget. I'd love to, though! Actually, the way the design is going to have to work is for my roof to be a 3rd leaf--that's the only way for it to ventilate properly. I know that the 3rd leaf is evil, but I'm in a similar predicament that Greg from onpurposeproductions was in in his build (don't have time to find the link right now).The ceiling of the outer structure will be my 2nd leaf. Long story short, the ceiling height in the LR will be the same as in the CR. Given that, do you have any thoughts about the design? Thanks for your interest!

Given the question that Lilith_envy just asked, I thought I'd post more pictures. One shows the new addition and roof framing from the inside. For me to be able to vault the ceiling in the live room, I'd need to install a ridge beam to pick up the roof load, and who knows what else in order for the structure to remain sound, once the ceiling joists were elimated. Sure would be nice, though.... You'll notice that the header over the door looks to be out of level. Actually, the header is level, but the east wall is about 1 3/4" lower than the west. Since I'm adding on to the front, and need to follow the existing roof plane, there's nothing I can do but follow the existing conditions for the new walls. Then there's a shot looking in the opposite direction, just showing the general condition of the existing room (sorry for the mess!) The third shot is a close-up of the existing sheathing. This garage is 100 years old, and the sheathing shows it. xSpace's advice when I asked about adding another layer of sheathing to the outside was that I should do it, and then "sandwich" the old sheathing by adding another layer inside, between the studs, which I'm planning to do. However, I'm also considering caulking all these seams and filling the knot holes with Fix-All, giving me a third good layer to the outer leaf walls, unless that just seems like a waste of time to any of you experts out there... Anyway, I hope these shots help to illustrate what I have to work with. Thanks, Mark

I'm wondering if I left something out, or if people are just really busy right now. I'd really appreciate some input on my basic design concepts from any of you experts out there before I move forward. Thank you!! Mark

You might find you only get a response when you a) ask a question or b) Appear to be doing something wrong. I'd take the lack of response as a good thing. Shame about the roof. That height would be great if you could change the truss down that end to a hip or sissors truss.

Hi-- Thanks for the reply. I suppose I could talk to an engineer to see if a scissors truss could be built in place. That's probably worth exploring. However, once the truss was built, I would still lose quite a bit of my height, especially once I framed the inner leaf ceiling. Still, thanks for stressing how nice that would be. I still (theoretically) could do it. Perhaps I shouldn't close the book on that idea yet.... Regarding questions, I do have several questions, but they're peppered throughout my posts. I'll cut and paste the most important ones here: This first one refers to my first post, where I'm exploring a one-room design with a "move-able" wall:

Here’s where I get to the compromise I mentioned earlier: I’m working on designing a moveable wall in three sections. The two outer sections would be framed in 2x6 with one or two layers of mdf running down the center. The mdf would be covered on both sides with 2” of 703 or something like it. The center section would essentially be a typical insulated glass door, with the doorjamb framed in 2x4, which would rest against 1 ½ x 2” stops attached to the inner frame of the outer sections. All three sections would have wheels on the bottom (like they do with an Ampeg 8x10 speaker cabinet) to facilitate moving around the room. Isolation-wise, I think the door would be my weak link, which might affect whether I decide to do one or two layers of mdf in the other sections. I would build them in such a way so that there was a gasket all the way around, to help with isolation, as well as a solid section of wall on the inner leaf for it to rest against. While I know this would be nowhere near as good as a double wall, it would give me some flexibility with back wall placement in the CR. The wall could be closer to the desk when tracking drums, for instance, and farther back when mixing. You can see by the Sketchup design that I’ve put large traps in the back corners of the room. I suppose these could be made moveable, similar to dynamike’s: viewtopic.php?f=2&t=8205&start=60 so that I could use them when mixing, as well. The two side sections could also be stored diagonally up against the bass traps on the back wall when not in use. I know this would be a lot of work for less-than-ideal results, but I really like to hear what things sound like through the monitors rather than through headphones as I’m recording. I suppose I could also configure these to make a vocal booth, as well. Question: does this seem dumb, or do you think it could be worth doing? I’m confident in my carpentry/design skills that I could build this in a way to make it safe and relatively easy to move around.

This next one refers to the post where I'm trying out a two-room design and I'm concerned about that limited CR depth that I have to work with, leaving the listening position basically halfway between the front and back walls:

Hello again-- So, I've been working again on a two-room design, which I'm still not sure about. I played around quite a bit a while back, inspired by John's "Small Studio in 3-D": viewt ... f=1&t=5457 In other words, orienting the CR sideways, next to the LR. Given the dimensions I have to work with, however, I finally decided that my building is too narrow to execute this design very well: the control room would not be long enough front to back. So in the last few days, I've been working on the the design attached below. The first change I made from version 2 and 3 is that I narrowed my "garden storage area" located behind the carriage doors down to 3' wide. This will force me to build an additional small shed to make up for the storage lost, but if this is a better design, then so be it. Doing this gives me an additional 2' in length to work with, which I will sorely need if I abandon my "moving wall" idea. The design would still be entirely inside-out walls with two layers of 5/8" drywall. I'm still leaning towards building the ceiling normally, using clouds for treatment, but I guess I'm still up in the air about that. All the yellow areas would be treated with insulation. I would still have slot resonators angled at 6 degrees extending past my listening position, with 30 degree soffits in front. The bass trap behind and to the right of the listening position would be moveable, so that I could keep the existing door to the outside in its present location (the other two plans call for just eliminating that door). The wall area between the bass traps and the slots would be cloth-covered inside-out walls. I'm hoping I'm not overdoing it with absorption in this room; my thinking is that the glass door to the LR, the top part of the soffits (tan area), and the slats will keep things lively enough. I know that a room of this small size will need a lot of treatment, hence my decision to build inside-out (no room to spare). The CR room ratio with this design is 1:1.27:1.52, close to Sepmeyer's 2nd. (95"0 ceiling height) My biggest concern here is that the listening position is almost exactly 1/2 way between the front and back walls. I really don't want to make the CR any longer, because I'm already afraid that the LR is going to feel too cramped as it is. Question: Is this one of those things that I can just deal with, or should I just go back to the one room layout?

Anyway, my biggest need for guidance at this point is on the topic of wheter it makes sense to pursue the one or two room ideas, given the limited space I have. The pros for the one-room idea are that I could have a little more room for just playing with other musicians when I want, and some flexibility as to where my back wall of the control room sits. The big cons would be poor isolation, along with the hassle of moving the wall around. The Pro of the two room design would be good isolation, but the cons would be that I would be locked into a smaller tracking room size, and that my listening position in the CR would be about halfway between the front and back walls. Anyway, that's where I'm at. Thanks in advance for any opinions regarding this dilemma!

I would hate to work in a one room studio. But I think of my self as an engineer 1st and a musicain 2nd. But it would be cheaper. A moveable wall defeats the purpose of having a big room and still won't allow you to monitor with speakers with out spill. My 0.02c

I'm not convinced the "movable wall" idea is even feasible. How would you manage to have it both movable and also totally hermetically sealed? Not to mention that it would be extremely heavy and difficult to move, plus the possibility that constantly moving it around might break something.

Yeah, the more I think about it, the more I think it's not a good idea. I agree that it's not realistic for it to be hermetically sealed (especially after moving it again and again). I guess I thought that even so, it would give me some isolation--maybe not enough to be worth all the trouble, though. And you're right, Stuart, it would be quite heavy, even in three sections. Believe it or not, the thought of losing control of it and dropping it on some equipment, or worse, a person, didn't really occur to me. So thank you, Lilith and Stuart, for "talking me down." So, assuming that "one room with a moveable wall" idea is dead, do you have any thoughts on the two-room design I came up with, especially the dimensions of the control room? I think the room ratio seems pretty good, but obviously, it's a small room, and I keep worrying about the listening position being in the center of the room. Am I too hung up on that issue, or is there a solution that I haven't thought of? I really don't want to make the CR any longer, because of how small the LR would be.... Thanks! Mark

Regarding the CR, Mark, you definitely do want to keep your head out of the 50% position, and closer to the 38% position. I think it is do-able in your room, but with some compromises. Right now your speaker / head geometry is based on a 60 degree equilateral triangle. In order to get your head closer to the front wall, you need to increase the intersection angle, and perhaps move the speakers a little further apart too. 60° is not written in stone: It is the ideal arrangement, but you can increase the angle of intersection of the speaker axes up to 90°, if you really need to, which would bring your head much closer to the front wall: The trade off is the size of your sweet spot: it will be squashed a little due to the tighter angle, and the stereo image might be stretched a little, but apart from that there isn't much of a down side. So changing the geometry will get your head closer to the front wall, which is what you have to do to get away from 50%. However, that also means that your desk will have to shrink a bit (either depth or width, or both), or there won't be enough room for you to get past the desk to the door into the LR. Maybe if you re-think your desk layout, what you are going to have on top of it, etc, you can come up with a desk shape that will work. maybe even make the desk itself more "wedge" shaped (narrower towards the front of the room, wider at the back, or a "wrap-around" shape that comes a bit around the chair on either side. Perhaps even have a folding panel on one side that you can drop down when you need to get past, or something like that. If you get really creative with the desk shape/size, I think you can probably fix it so that your head is in a better location and you can also get around the desk to the door. You just have to juggle the dimensions of the desk and the geometry of the speaker / mix positions, until you get the best fit. I think it can be done. - Stuart -

Ok--great advice--thank you. I will start playing with the speaker angles and see what I can come up with. One question: should I consider abandoning the soffit-mounting of the speakers given the restrictions I have, perhaps setting them on stands closer to my listening position (and thus being able to adjust the size of the equilateral triangle and make it easier to get past the desk into the LR) or do you feel that the benefits of soffit-mounting (lack of reflections, better bass response, etc.) outweigh the flexibility I might gain from this? Thanks so much! Mark

Personally, I'm hooked on the concept of soffits! Others might disagree (and many studios do have stand-mounted speakers), but to my mind the advantages of soffits outweigh the disadvantages. Also, take a look at ALL of John's designs: I can't recall a single one where the speakers are not soffit mounted! I might be wrong, but I think all or nearly all of his designs include soffit mounted speakers. For me, that reason alone is good enough. - Stuart -

Good point. I think there's one (http://www.johnlsayers.com/Pages/Flying_Fox.htm), but it's an old one. I'll play around with this and post a revision to the design when I think I might have something. And thanks again for your help! Mark

Soundman2020 wrote:

Personally, I'm hooked on the concept of soffits! Others might disagree (and many studios do have stand-mounted speakers), but to my mind the advantages of soffits outweigh the disadvantages.

+!. Andre

Ok-- So I've been working on a side-by-side design after wrestling with my other end-to-end design to try to fix the listening position. I didn't feel like I was coming up with a very workable desk size that still allowed me to get around it, through the door, and into the live room (at least not very comfortably). Anyway, I'm encouraged by what I've come up with (I hope you experts agree!!). The control room is very small, but the ratios are pretty good: 88":100":121", which is close to Sepmeyer's first ratio (with one caveat, which I'll mention in a moment). By adjusting the soffit angles (38 degrees, rather than 30), I've got the listening position right at 38% with an 80 degree intersection of the speaker axes. The ceiling slopes at 6 degrees from front to back. The control room walls are splayed at 6 degrees from front to back. As far as treatment goes, I'm thinking the CR should be built entirely inside-out. I've got bass traps on the back wall of the CR, one of which will have to be moveable to access the exit door (or I'll just move the exit door....sigh). I've also got slats that extend past my listening position. Anything in the CR that's not a trap, soffit, or slats, will probably be just cloth-covered inside-out wall. I didn't concern myself with room ratios in the live room; I was more concerned with just getting as much space as possible (by the way, Lilith_envy, I'm still toying with the idea of vaulted ceilings in the LR). I did splay the end walls 6 degrees, and I'm hoping that with the slats angled at six degrees on one wall and cloth-covered inside-out wall opposite that, I should be able to avoid most really bad flutter echoes. Also planning on having bass traps in all four corners of the LR. On to my questions..... The caveat I mentioned about my CR room ratio is this: The 88" ceiling height is the median height (since I'm planning on a 6 degree angle). That makes my ceiling height 6'10" at the front end of the room and 7' 11" at the back. I really can't do more than a 6 degree angle, because I would run out of headroom (literally!). If I build the ceiling normally, I will be almost exactly at Sepmeyer's first ratio. However, with that low ceiling height, I won't have much room for treatment. If I build the ceiling inside-out, That will change my height measurement by several inches, throwing off the entire ratio. With my limited room length, my best bet is to go for the first ratio--it's the only one that's within reach. Anyway, I'm inclined to just build the ceiling inside-out, even though that throws the ratio off, but what do you experts think? If I build the ceiling normally, would I have room for sufficient treatment? My second question involves the construction of the live room. I was planning on building it inside-out, but could there be a significant advantage (transmission loss-wise) to building it normally? Doing so would increase the thickness of my spring from about 4" to about 7 1/2" along both long walls of the room. Given the proximity of my neighbors, and my hopes to be generating sound levels up to 105 db, perhaps this would be a good trade-off (increased TL for reduced room size). I know I would then have more treatment invading my space, but maybe that would be worth it. Finally, I suppose the most basic question is this: how does this design look? does it appear workable? Most importantly, does the CR look workable? Thank you for any advice/feedback you can give!! Mark

I hope I'm not being impatient; just trying to keep the project moving. Does anyone have opinions about the designs/questions in my last post? Thank you for your help! Mark

In general, that looks OK, I think. A smaller room will need more treatment, so going inside-out makes a lot of sense.

By adjusting the soffit angles (38 degrees, rather than 30), I've got the listening position right at 38% with an 80 degree intersection of the speaker axes.

It should be 76°, not 80°, for 38 degrees! (Yeah, I know: you approximated, but I like to split hairs! :) ) Just checking here: You mean the position of your EARS is at 38%, or the position of the apex of the TRIANGLE? It should be your ears. But in any event, 38% isn't a magic "written-in-stone" number: just a good starting point.

The ceiling slopes at 6 degrees from front to back. The control room walls are splayed at 6 degrees from front to back.

IIRC, 6° splaying is for 30° soffit angles (and it should be 12° on the ceiling for that). Since your soffit angles are greater, you should also splay your walls more. I don't recall the exact rule, but for 38° you'd probably need something like 8 degrees on the walls, and maybe 15 on the ceiling. You say you don't have enough space for that, but maybe you do have enough space to do the FRONT half of the room like that, then flatten out the angles in the rear half? Maybe? Just a suggestion...

My second question involves the construction of the live room. I was planning on building it inside-out, but could there be a significant advantage (transmission loss-wise) to building it normally?

Not if you build it with the same air gap, mass and insulation. In other words, it doesn't matter which side of the leaf you put the studs on, provided that the leaf itself is at the correct distance. The studs can either go inside the wall cavity, or inside the room. For the same position of the leaf (air gap), same mass, and same amount of insulation, you'll get the same isolation. The advantage of putting the studs inside the room is that it gives you some place to put your treatment, partly sunk into the wall itself, between the studs. If you wanted to use a smaller air gap, then you can do that, but you should compensate for the higher MSM resonant frequency with more mass on both leaves.

Doing so would increase the thickness of my spring from about 4" to about 7 1/2" along both long walls of the room.

If you can afford the space to get your air gap up to that depth, and you really do need good isolation, then I'd say "go for it"!! No doubt about it! Bigger air gap lowers the resonant frequency and improves isolation. But the point isn't about where the studs go: it is about where the leaf goes. The studs are just there to hold the leaf up. It is the leaf itself that does the isolating. So maybe you can come up with a good compromise on that. Don't forget that in a really small room you can also save precious millimeters by borrowing from the "beef up between the studs" idea, going with just one layer of drywall on the studs themselves, then the second layer in between the studs. You could also use something thinner and more dense instead of drywall, but your cost will go up. In the design for my room, I'm replacing drywall with fiber cement panels ("Duraboard") that are nearly twice as dense, so I can get the same mass in half the depth. By using both of these ideas, and inside out walls, I'm gaining 2 1/2 inches of room length without compromising my air gap. 2.5" isn't much, but every inch counts! Sure, it costs me much more too, but it's worth it (to me at least). My 0.02 - Stuart -

Thank you for your input, Stuart. It helps a lot. So, a couple more questions....

It should be 76°, not 80°, for 38 degrees! (Yeah, I know: you approximated, but I like to split hairs! ) Just checking here: You mean the position of your EARS is at 38%, or the position of the apex of the TRIANGLE? It should be your ears. But in any event, 38% isn't a magic "written-in-stone" number: just a good starting point.

Actually, I didn't approximate--I guess my lack of math and Sketchup skills conspired against me! :oops: Yes, I do mean that the position of my ears is at 38%. If 38% is not written in stone, I might cheat it back a little to save myself a bit of wall angle (see next comment).

IIRC, 6° splaying is for 30° soffit angles (and it should be 12° on the ceiling for that). Since your soffit angles are greater, you should also splay your walls more. I don't recall the exact rule, but for 38° you'd probably need something like 8 degrees on the walls, and maybe 15 on the ceiling. You say you don't have enough space for that, but maybe you do have enough space to do the FRONT half of the room like that, then flatten out the angles in the rear half? Maybe? Just a suggestion...

This didn't occur to me, but it makes sense. Any idea where I might track down the exact rule for the relationship between the soffit angles and the wall angles? I've searched for it using any keywords I can think of, but no luck. If I can't find the rule, perhaps I'll just use your suggestion for approximately 8 degrees for the walls. As far as the ceiling angle goes, I knew that 6 degrees wasn't enough, but I didn't think of doing 12 degrees (or 15, in my case) for only half the room length. Would this be ok as long as it extends past my listening postion? Should I then use a shallower angle after that, or could I get away with a flat ceiling past the halfway point? Regarding the LR, I think I'm clear on the idea of leaf positioning; what I was getting at is that I don't think I can afford to build the inner walls inside-out and have a 7.5" air gap at the same time--I'd lose a lot of space in the room that way. However, if I built the walls normally, that's where I would get that extra 3.5" of air between the leaves (mass-framing-air-framing-mass--I get my 7.5" measuring from the back side of the drywall on the inner leaf to the back side of the drywall on the outer leaf.). Perhaps what you're saying is that the amount of treatment I would need to compensate for drywall in the LR would eat up that interior space anyway, so if I want that additional air gap I need to just resign myself to losing the floor space in the LR. Or maybe I'm not explaining myself clearly enough :oops: Finally, one more question, that I posted earlier about my room ratio in the CR:

If I build the ceiling normally, I will be almost exactly at Sepmeyer's first ratio. However, with that low ceiling height, I won't have much room for treatment. If I build the ceiling inside-out, That will change my height measurement by several inches, throwing off the entire ratio. With my limited room length, my best bet is to go for the first ratio--it's the only one that's within reach. Anyway, I'm inclined to just build the ceiling inside-out, even though that throws the ratio off, but what do you experts think? If I build the ceiling normally, would I have room for sufficient treatment?

To clarify, I'm calculating my ratios in the CR by measuring from mass to mass on my inner leaf, inside-out walls. The length of the CR in this design is set in stone--I can't make it any longer with the CR running along the shorter axis of the outer garage structure. Therefore, I have to use the length as my starting point in figuring my ratios. Unfortunately, The short length of the room causes the room height to be pretty low when I crunch the numbers. I know that it's preferable to have a soft ceiling with a hard floor, and that's why I want to build the ceiling inside out, but building it that way would increase my room height and throw off the ratio. It seems I need to compromise in some way here; I'm just not sure what to compromise on. IF only I could just build this from the gound up.............

If 38% is not written in stone, I might cheat it back a little to save myself a bit of wall angle (see next comment).

Sure! As long as you stay well away from 50% and 25%, then you should be OK. Moving forward or backward a couple of points is no bog deal.

As far as the ceiling angle goes, I knew that 6 degrees wasn't enough, but I didn't think of doing 12 degrees

Yup. In fact, it's really the same rule for both walls and ceiling: For a 60° speaker angle, you need 12° splay, total, between parallel surfaces. The difference is that with the walls you can go 6° on each side, but in teh vertical plain it's probably not a good idea to angle your floor 6°, so the ceiling has to take the entire 12°.

I don't think I can afford to build the inner walls inside-out and have a 7.5" air gap at the same time--I'd lose a lot of space in the room that way.

Actually, it's the other way around! For a small room, you can't afford NOT to! Or at best, it's the exact same thing. Think of it this way: If you build normally with your inner leaf at 7.5, then you still have to add the room TREATMENT on top of that anyway, so you'll be losing the depth of the treatment, which is most likely at least 4", no matter what. So you might as well have the studs there,on the same side of the leaf as the treatment, surrounding it and helping to keep it in place. It gives you things to nail / bolt / screw / hang your treatment onto, right there and visible, without having to worry about making holes in the leaf itself (for example, from miscalculating where the stud is...). It also makes it easy to install your electrical, since you can do it right there on the side of the wall that you can see, once again without having to make holes in your leaf to fit cables, conduit and boxes. Etc.

I get my 7.5" measuring from the back side of the drywall on the inner leaf to the back side of the drywall on the outer leaf.

Correct! So the question remains as to which side of that leaf you want to have the studs on: The treatment inside the room will take up the same depth, regardless of where the studs are, and that depth will be at least as much as the studs, no matter what, so to my mind it makes sense to have the studs where you can see them and use them, and not penetrate your leaf all the time.

Perhaps what you're saying is that the amount of treatment I would need to compensate for drywall in the LR would eat up that interior space anyway, so if I want that additional air gap I need to just resign myself to losing the floor space in the LR.

Yup! But it's not just the LR I'm taking about: The CR is the big deal, usually. In fact, the LR might not need that much treatment, depending on what you plan to do with it. So with the LR, you can probably go with either inside-out or normal construction, without too much hassle, but for the CR I still reckon John's "inside-out" principle has real advantages.

I have to use the length as my starting point in figuring my ratios. Unfortunately, The short length of the room causes the room height to be pretty low when I crunch the numbers. I know that it's preferable to have a soft ceiling with a hard floor, and that's why I want to build the ceiling inside out, but building it that way would increase my room height and throw off the ratio.

So flip your ratio then! Sound waves don't care which way is "up" and which way is "across", so you can easily flip your ratio and use what would normally be the "width" dimension as height, and what would normally be the "height" dimension as width. Not sure how that would work out in your case, but if you now take the very best maximum height that you can get out of that room and consider that as being "width" in the calculation, then whatever number pops out as "height" would then by your room width. Try it with a couple of different ratios, and see if one of them gives you a god number, then go with that.

It seems I need to compromise in some way here; I'm just not sure what to compromise on.

Tell, me about it! "Compromise" is actually a synonym for "studio design".... After all, it would be no fun if you didn't have to carefully figure your way through all these compromises along the way! :) - Stuart -

Great. Thanks, Stuart--you've been a huge help. I'm up skiing for a week now, so my revisions will have to wait until I return, but I've got some homework to do now as far as room ratios for the CR. I didn't realize I could "flip" the dimensions; hopefully I can tweak things in such a way as to get closer to my target. I'll continue to process how I want to build my walls in the LR, but I think I'll do them inside-out. I suppose one thing I should do is make some music in there and take some readings once the outer leaf is all beefed up to get a feel for how much further I need to go to get the TL I'm after. If I think I can get away with just a 4" spring at that point, I suppose that will be my answer. Thanks again for all your help! Mark