Frost Wall Foundation necessary in VT?

This is my first post. I've read Rod's book, the stickies in this forum, messed around in sketchup, and read through a good amount of the studio design forum (and some of the others). Proposed new construction in Vermont: I’m looking to build a studio that can multitrack a 4 person rock band at full volume. My nearest neighbors are about 250 feet away, but I live in the country and it’s quiet most of the time, and they’re nice but doubt they’ll want to hear me tracking drums at 2 am. I’d love to start this summer, but given the nature of the design process, I’m no longer certain this is possible. 20'x21'x8.5'(sill height), with a 17’ roof beam height - cathedral ceiling with a stick belt/bearing ridge pole roof (no cross beams). 2x4 walls, bigger for ceiling joists (probably 2x8 or 2x12). 2 leaf construction, with exterior layer in the ceiling buttressed by 2 layers of drywall between the joists, and for the exterior walls, probably the same. Interior wall, 2 layers of 5/8 drywall green glued together. Insulation between the studs (both walls) and joists, independent framing. No floating floor. Planning on running a subpanel out to this new structure, star grounding. The design will be pretty close, I think, to the design I've attached to this post, that I found in one of the stickies. I’m still not certain about how to handle heating, cooling, and ventilation. Based on Sharward’s thread, I’m leaning towards some sort of HRV/ERV system with an inline fan for fresh air. HVAC equipment will be situated on a concrete pad adjacent to the structure in a small shed. Shed and pad will also be new construction. I'm currently getting bids from design/builders to put in the foundation, framing, siding, and roof. I have budgeted no more than 20k for this part of the project. Since this structure is modeled on my garage, with the exception of the cathedral roof/ceiling versus the garage's crossbeam style, I thought I'd get bids in the 10-15k range. However, the first bid came in at 35-42k. The biggest extra expense seems to be the recomendation for a frost wall foundation versus a concrete slab. Frost wall is estimated to be 10-12k..that’s a lot of dough. If I can go with a slab instead, then the other variances (I asked for cedar siding – just go with vinyl instead, and other negotiables like that) I can probably address. Thus, this frost wall is looking like a potential deal killer, at least for starting this year – I’d need to save up more money if it’s necessary. Therefore, my only question at this time, is: Can I do a slab construction or is it too much risk for heaving given Vermont’s 6 month winters? Okay, well, one other question: Will the acoustics of the control room be difficult, given that the ceiling in this design slopes down from the front of the room, going from 18’ to 8.5’ at the edge of the room? Thank you for having such a fantastic forum. Charles

Therefore, my only question at this time, is: Can I do a slab construction or is it too much risk for heaving given Vermont’s 6 month winters?

Hey Charles. That is a question better answered by your local building inspection department. While there you could get more information on using a Frost Protected Shallow Foundation (FPSF) for your build. http://www.toolbase.org/PDF/FieldEvalua ... B_fpsf.pdf Downside to the fpsf type is it reads that it is used in a dwelling and that a 64 degree temperature is expected to keep this thing working right...I think that is what it said. Upside is the claim is it helps reduce building cost.(in a family dwelling)

Thanks xSpace for the help on the foundation. It looks like we'll be able to use an "Alaskan Slab" which is a reinforced slab with 3" XPS insulation surrounding it. MUCH cheaper than a 4' frost wall! Dimensions of the building have swollen to 24' x 24', with ceiling height of about 18.5'. I've attached two drawings, and a sketchup file. These files (after some tweaking) will be used to get an initial cost estimate for the "core" building: slab, framing, exterior, roof, running subpanel from house to this new construction (it's close to the house). It looks like we have a decent shot of bringing this in around 25k, which is my budget, but we'll see how the estimates come in. I'm concerned primarily with the "core" right now - these drawings, for example, don't have line of sight between the rooms yet, and I will likely use single "super doors" versus the double doors shown here. Lastly, 3 layers of gyp are listed here, but I'm likely going to use 2 layers + green glue. My questions: 1. I've seen distances of as little as 1" and as much as 6" between the framed walls. I'd like to go with 1" - how much downside am I looking at versus, say, 6"? 2. HVAC design. We're planning on having a small shed on a concrete pad next to the studio which houses the HVAC equipment. Currently leaning towards HRV with an inline exhaust fan for fresh air, with the ductwork going in between the roof and interior ceiling framing, so that it will be easier to get to every room with ductwork. My question is, can I get away with no AC. I'm in Vermont, it does get hot in the summer, the equipment gets hot too, and of course sweaty rock musicians increase the humidity. But AC is a pain the @#$. And, is anyone willing to throw some numbers out for how much I might need to be spending for a) HRV w/exhaust, no AC and b) same, but w/AC? I'm assuming I won't be able to install this myself...will I? I'm somewhat handy. I'd like to keep cost for HVAC under 10k; 5k is the dreamy number. Total interior cubic feet ~6000. I don't think I'll need to get HVAC into the ISO rooms, just the control room and recording room. Thank you! Charles

chubbar wrote:

1. I've seen distances of as little as 1" and as much as 6" between the framed walls. I'd like to go with 1" - how much downside am I looking at versus, say, 6"? Thank you! Charles

The difference will be in the walls being able to isolate the lower end of your sound. How much it helps or no depends on the mass of the walls, collectively, also. While 6 inches may be more better, you simply may not have the room for that. Many have had success with the use of a 1 inch separation between framing, and so should you ;)

Hey Charles, Nice layout! I wish I had that much space... Regarding HVAC, I've been looking into that for my build, and some of the comments I've read here highlight the fact that, in building a studio, we surround the thing with acres of really thick, very efficient thermal insulation, plus we put thick walls around it with large insulating air gaps, then we go and seal the damn things airtight! Clearly, this creates a very, very well insulated hermetic bubble, where heat accumulates rapidly, since it has no other place to go. So my guess would be that, unless your ventilation system can move huge quantities of air rather fast (which would make lots of NOISE!), then you probably will need air conditioning. Have you looked into the "mini-split" type of air conditioning system? That's what I'll be using in my studio. I already have a couple of them installed in various rooms in my house, and they work fine: They are also reasonably quiet, and best of all, they are not too expensive. Mine cost under US$ 1,000 each, installed, but they are small (10,000 BTU/hr). Bigger one are available too, but for my space, that's plenty. It might be worth thinking about. - Stuart -

Regarding your question on the separation: Below is a graph from an old paper on the acoustics of wall design, that shows the effect of larger and smaller gaps. Careful! The numbers are NOT just for the air gap! They are for the ENTIRE wall thickness, from the outside face of the outer leaf to the inside face of the inner leaf. Also, the dB numbers are not straight Transmission Loss (TL): They refer to how much BETTER the TL is for each case, as compared to normal mass law. So, assuming that you are using 2x4 framing double stud walls, if you have about 1 inch of separation between your frames (inner leaf to outer leaf), and two layers of GB on each side, then your total wall thickness would be around 9 inches, so your TL would be around 15 dB better than mass law. If you increase the stud separation to 4 inches, your total wall thickness would be around 12 inches, and you'd have a bit better than 20 dB above mass law. In other words, reducing your stud separation from 4 inches to 1 inch will cost you about 5 dB in transmission loss, theoretically. Of course, read the fine print: Those numbers are valid for frequencies in the range 125 Hz. to 4 kHz., and are not so good at lower frequencies, and they are theoretical! Reality might be somewhat different! But at least that should give you an idea of what the "penalty" is for narrowing your gap, and figuring if you can live with it or not. Don't forget that stuffing the entire gap full of rock wool or fiberglass also helps a lot. - Stuart -

Stuart, thanks for your help. I went with 2" between the walls, the info you provided was very helpful in deciding. For HVAC I finally decided to go with an inverter that both cools and heats (looks like either a sized Mitsubishi citi-multi or a daikin vrv-s), with an inline fresh air fan in the attic, and the inverter in the mech room. I've attached some of the drawings I am about to send out for pricing estimates. I'm working w/an architect for the planning, but he's never built a music studio before. So I'm concerned about the volume of my recording room. It's about 2200 cubic feet with a vaulted ceiling that starts at ~8' 9" and goes up to an interior peak of ~11' 6". But that darn HVAC and it's ductwork are taking up a lot of vertical space (I'm bitter about it, yes!!). Of course, I need to get the best possible acoustics from it with a minimum of deadening treatment. When it's just me recording, I can open up the iso room door and maybe put a door in the other iso room and open that too, thereby gaining about ~500 cubic feet. But when I'm recording full bands I won't be able to do this. I'm expecting to need corner bass traps, and some of the predictable absorptive treatments, but I'd really like to have it be as warm, undeadened-sounding of a room as possible. Is this not realistic for this size room? Am I doomed :cry: to deadening it and forever applying reverb to every drum mix?? For example, I'd love to be able to put a couple of stereo tlm149s for room mic's on a drum mix and actully use those tracks because they sounded good. To that noble end, what do you think about the following ideas: Idea1 - Expand the effective volume. Basically, expand the volume of the recording room by using (something like) insulated flexible hvac ductwork that would run through the 2 leaf walls - maybe about 14" diameter so it fits between the wall studs - into the hvac attic, where I will have built between the hvac ductwork some sort of pre-constructed double ply insulated box. If I put the sound tube near the floor of the recording room, it could grab some of those low frequency waves and send them "upstairs." Or alternately, I could run the sound tubes into the mech room. Then I could soundproof the mech room by soundproofing from the service platform downward. (This could also serve as an amp room.). the flexible hvac ductwork would preserve the structural 2 leaf system, and I could make some "inserts" that would cover up the holes when expanded room volume wasn't called for. Idea 2 - Take away the vaulted ceiling for a flat ceiling that thereby gives more volume, but then has parallel ceiling/floor. Which one would give me better acoustics? Cheers from Vermont, Charles

Hi...politely wondering if I need to provide more information to my question?

Hey Charles! I guess your post got missed in all the recent flurry of activity on the forum!

It's about 2200 cubic feet with a vaulted ceiling that starts at ~8' 9" and goes up to an interior peak of ~11' 6".

That sounds like a reasonable size and height. More is always better, of course, but those don't sound too bad, to me at least. If that's what you can get, then its enough.

When it's just me recording, I can open up the iso room door and maybe put a door in the other iso room and open that too, thereby gaining about ~500 cubic feet. But when I'm recording full bands I won't be able to do this.

Opening doors for cooling / ventilation is an option that I've seen discussed and approved in some places, but personally I don't see it as being a good idea. Air won't decide to move in and out of a sealed booth with the door open, all of its own accord. It will take a long time for warm stale air to move out, and cool clean air to move in, unless maybe you put a fan on the floor to "help" it a bit. But that's a bit of an ugly kludge, if you ask me. It will work, sure, but for me, I'd prefer to have proper cooling / ventilation in each room / booth. But that's just me. I know others do use the "open-the-door-and-wait" technique quite happily.

I'm expecting to need corner bass traps, and some of the predictable absorptive treatments, but I'd really like to have it be as warm, undeadened-sounding of a room as possible.

Are you talking about the live room, or the control room? The LR you should treat the way you want it to sound, but the CR needs to be treated for the best possible neutrality, otherwise your mixes won't translate. You don't want your CR to add too much "character" or "color" to what you are hearing from the speakers, as that would make your mixes not translate. So your CR will need oodles of bass trapping, mostly dead ceiling, mostly live floor, good absorption on all of the first reflection points, and probably lots of other treatment which you'll only be able to decide on once you have done all of the above and and actually tested the room to see how it is responding. About your "volume expander" idea: I don't think that will work. The tubes will coupe the spaces, of course, but they will probably act as some sort of weird Helmholtz resonator, accentuating certain frequencies and killing others. The impedance mismatch in and out of those tubes would be pretty large, so I reckon you'd get all kinds of strange and wonderful honky clanky things going on! I can't see it doing anything useful, and probably it would just make for an acoustics disaster. Acoustically coupling two spaces is pretty hard to do transparently.

Idea 2 - Take away the vaulted ceiling for a flat ceiling that thereby gives more volume, but then has parallel ceiling/floor. Which one would give me better acoustics?

In my non-expert opinion, I'd say that more volume is preferable to a vaulted ceiling. More volume is always good, acoustically (except when the extra volume is down the other end of a pipe! :) ). So I think I'd maximize the volume at the expense of the vaulted ceiling.

I'd love to be able to put a couple of stereo tlm149s for room mic's on a drum mix and actully use those tracks because they sounded good.

Take a look at Lou's build! He has a space similar to yours for his drum room, and a few days ago he posted some samples of some pretty damn good drum recordings he did on that room. Take a look at how he did it, and you should get some ideas about how you can do it. Of course, he went to some amazing extremes with his build, but you should be able to get convincingly close in your drum room on a smaller budget. - Stuart -

"Idea 2 - Take away the vaulted ceiling for a flat ceiling that thereby gives more volume, but then has parallel ceiling/floor. Which one would give me better acoustics?" How do you reduce a ceiling height and increase volume by doing so? That doesn't make sense.

How do you reduce a ceiling height and increase volume by doing so? That doesn't make sense.

Sorry...I don't know why but it made complete sense when I wrote it! I'll try not to waist your time like that...although perhaps raising the wall height and decreasing slope of the roof? On the other hand, Stuart saying my 2200 cubic feet of room volume will be workable has me feeling a lot better, so I can I think at this point abandon my desparate attempt to gain room volume...and move on to other fun things.

Opening doors for cooling / ventilation is an option that I've seen discussed and approved in some places, but personally I don't see it as being a good idea.

Oh yeah, to clarify, I've got HVAC going to all the rooms, I was thinking to open the iso room door(s) in order to gain volume while tracking. But that might mess with my (at that point) finely tuned room acoustics, right?

Are you talking about the live room, or the control room?

Yeah, I was talking live room. I really love (who doesn't???) a drum set tracked with a warm roomy vibe a la (of course) bonham. If I can't get a good drum sound out of my room, I'd almost rather not build the studio. Might sound a bit dramatic, but it's quite important to me to not have one of those 80's anechoic room sounds.

So your CR will need oodles of bass trapping, mostly dead ceiling, mostly live floor, good absorption on all of the first reflection points, and probably lots of other treatment which you'll only be able to decide on once you have done all of the above and and actually tested the room to see how it is responding.

Thanks for the rough guidelines, I still need to focus on CR acoustics (add it to the list!). I imagine I'll build some hefty bass trapping (as rec'd), etc. But for now, trying to make sure I get the live room built well enough to give it the chance to sound great post-acoustic treatment.

Take a look at Lou's build!

Thanks, I'm going to digest his quite impressive build...lots of information there. Next up I think I'm going to have questions about wiring troughs versus running conduit under and up through the slab...but I'm going to research a bit more first. Thanks guys!

chubbar wrote:

How do you reduce a ceiling height and increase volume by doing so? That doesn't make sense.

Sorry...I don't know why but it made complete sense when I wrote it! I'll try not to waist your time like that...although perhaps raising the wall height and decreasing slope of the roof? On the other hand, Stuart saying my 2200 cubic feet of room volume will be workable has me feeling a lot better,

You are not wasting my time, but both you and Stuart seem to be agreeing that you can get more volume in a room by taking away the higher ceiling. This is just mind numbing to me.

so I can I think at this point abandon my desparate attempt to gain room volume...

Well, I wouldn't abandon it yet, if there is a chance that you can gain something! Extra volume is good. The more the merrier!

although perhaps raising the wall height and decreasing slope of the roof?

Sounds like a plan! If you can raise the walls, then go for it. But can't you also raise the roof to go along with the walls?

...in order to gain volume while tracking. But that might mess with my (at that point) finely tuned room acoustics, right?

Not necessarily! Changeable acoustics is not a bad thing. That's the purpose of gobos, for example: Move them around to change the acoustics, as needed, in the studio as a whole, or in parts of it. Opening and closing doors is kind of similar, and might be a good thing, too. It might well change the acoustics agreeably, and is certainly worth a try! You could even maybe try to figure that in to your design, so that doors swing open into a place where they can be used usefully as reflective surfaces. Or maybe even as absorptive surfaces, if that's the way you build them. In fact, maybe you could build your doors as gobos.... or use gobos for doors ... :) the mind boggles! But seriously, having the ability to change the acoustics of your room is a good thing. Gobos, hinged panels on the walls, sliding panels, etc. So why not use booths and their doors?

Might sound a bit dramatic, but it's quite important to me to not have one of those 80's anechoic room sounds.

Oh please, no! Not that! Anything but that! I promise to be a good sound engineer, if you'll never, never, never punish me by making me track or mix in an anechoic chamber! I promise! really I do!!!! :) Yeah, I hear ya! A dead "live" room is kind of a contradiction in terms! It's hard enough to get a good sound of a drum kit already, without torturing it in an acoustic "death" chamber! I'm not very knowledgeable on live room treatments for specific instruments, but I'm sure folks like John, Rod, Ethan, et. al. can offer you good advice on how to do that. My guess (and that's all it is: a guess!) would be fairly heavy absorption on the ceiling above the kit, so you don't get comb filtering in your overheads from ceiling reflections, semi-absorption, semi-reflection on the wall right behind the kit (maybe one of John's slot resonator walls?), maybe even some diffusion(?), to keep some life in the sound, but trap the heavy stuff so it doesn't overwhelm the room sound, and doesn't give slap-back echoes into the mics, and then the rest of the room reasonably reflective with some absorption and diffusion, .... But I'm just thinking out loud here, and I can't point you at any papers or research that I'm aware of to back up those "hunches". If there's one thing I've learned about acoustics, it is that hunches can be a dangerous thing if there is no science behind them, so take the above for what it's worth!

Thanks for the rough guidelines, I still need to focus on CR acoustics (add it to the list!). I imagine I'll build some hefty bass trapping (as rec'd), etc....

Yep, Rear wall/wall corners are good for that, but there are plenty of other corners that you can use. You need a lot of bass trapping, especially in a small room.

But for now, trying to make sure I get the live room built well enough to give it the chance to sound great post-acoustic treatment.

Maybe you should take a flexible approach to the live room? Perhaps even modular? In the sense that you can plan some basic treatment initially, but leave space for trying out variations once it is built, without having to destroy and re-build anything. I'm think that it might be an idea to build several identically sized "modules" with different acoustic properties, that you can either stack, or hang on the walls, or whatever, but with the ability to "mix and match", move them around, see what effect they have, experiment, etc. Have some reflective modules, some absorptive modules, some diffusive modules, etc. Then see what happens if you fill one wall with absorbers and the opposite wall with diffusors, or 50/50, or 75/25, or.... Just an idea. - Stuart -

I think you would have to raise the wall height(from 8'-9") an additional 15-1/2 inches just to get back equal to the volume you had with the vaulted.

You are not wasting my time, but both you and Stuart seem to be agreeing that you can get more volume in a room by taking away the higher ceiling. This is just mind numbing to me.

I guess your mind numbs too easily!!! :) Nobody said anything about "taking away the ceiling height". The question was about substituting a flat roof for vaulted roof in order to gain volume. Quote: "Idea 2 - Take away the vaulted ceiling for a flat ceiling that thereby gives more volume, but then has parallel ceiling/floor". IE, take away the CEILING, not the ceiling HEIGHT. Different things. See below for a couple of simple SkethUp models of what I was imagining, based on the original description. The flat ceiling version clearly has far more volume, since the vaulted ceiling has been "taken away". ... QED

Have you looked into the "mini-split" type of air conditioning system? That's what I'll be using in my studio. I already have a couple of them installed in various rooms in my house, and they work fine: They are also reasonably quiet, and best of all, they are not too expensive. Mine cost under US$ 1,000 each, installed, but they are small (10,000 BTU/hr). Bigger one are available too, but for my space, that's plenty.

holy cow. hvac estimate came in at $35,000. fuggedduboudit. so I'm going to have to do the mini-split thing. the hrv/erv system i was going to use was 36,000 btu, but maybe that was overkill? what's your room volume? how are you handling the fresh air? I'm wondering if I can go with two units and branch each unit into an iso room as well? thanks!

How do you deal with the minisplits since they dont pump in fresh air from the outside?

How do you deal with the minisplits since they dont pump in fresh air from the outside?

You run fresh air ducts with fans, silencers and bends, following the same basic principles as for ducted air conditioning.

Okay, still struggling with the HVAC issue. I’ve attached a design that is similar to sharwards – fresh air fan + HRV/ERV. My question is about the ductwork. I’ve been reading many build threads including sharward, soundman 2020, bassman, and Lou’s, and tried to answer questions that way first, but I’ve still got a few. Given what I think I know at this point I’d like to use the flexible acoustic ductwork hung from the joists (between the outer and inner leafs), with inline silencers and 90 degree bends, and lining inside of the duct if necessary, because this seems to be the most affordable and easiest option, and seems to me like it might be effective…which is why I’m here to bounce the idea off you guys... As such, here are my questions: - If I run the flexible acoustic ductwork through the ceiling joists, since it will be outside of the room, do I still need to insulate it, or should I focus instead on lining the ductwork? Although this picture doesn’t show it, I plan on having at least one 90 degree bend in each duct run, and a silencer plenum designed as described in this forum with rigid fiberglass lining, etc. o Is there a DIY method to line the ductwork rather than buying $$$ lined ductwork? o My contractor rec’d 20” ductwork, but that seems to be larger than folks on this forum use. If I use 90 degree bends, lining, and silencers (at the point of penetration as described by Rod) can I get away with smaller – say 14” ductwork? Oh yeah, I’m planning on having a damper as well in the HVAC system, although I don’t fully understand how these things work yet. Cheers! Charles - I initially had rigid lined ductwork that was super expensive; this acoustic ductwork seems to be much cheaper. Could someone comment on tradeoffs here? - Do I need to have silencers, lining, and 90 degree bends in the return ducts as well?

Charles - check out this unit: these units allow for fresh air to be added - you mount them up in your ceiling cavity and run insulated flexible ducting to your rooms.

If I may comment on that; Using flexible ducts might be easy to work with, but it does provide more resistance in airflow. However, flexduct is a bit more quiet.

Thanks John and Ro!

Okay, call me crazy, but it's double the cost to pay someone to install my heat pump + separate fresh air fan mechanical system. I'm not rushed for time, so I'm going to try and do it myself. Rod's book says there's several good books on the market on this topic, but after searching amazon I'm still not sure what's good. Does anyone have some recommendations of books/online resources? The guy who helped me design my system recommended I ask " alot of questions" of the place I buy the equipment from. I plan on doing that, but this forum also has many experts. In other news: with some grumbling, I managed to receive zoning approval for commercial activity at the public hearing. It's a go! I've put money on deposit and expect to break ground in a couple weeks if the other permits go thru okay. Crossing my fingers... thanks! Charles

Long time lurker of this forum. Decided it's time for me to join when I see a fellow Vermonter planning a build! I'm still in the research and raise funds phase, but hopefully can gain some more knowledge and assistance from this forum in my future projects! Where in VT are you located? Living in the Burlington area, I don't see really any properly designed spaces...

Hey erikhoppy, nice to hear from a fellow VTer, I'm not far from you - in Hinesburg. I don't think I could have gotten even this far without this forum, I definitely lurked for awhile too and I still am lurking! Of course there's Phish's "Barn" in Richmond and I hear Chaz Eller's got a great setup, I think he's in Charlotte. I think there's more hiding out in the woods that we just don't hear much about - you know how these crazy Vermonters are! My band might be recording at a well designed project studio in Stowe that sounds pretty good. Not sure about the Burlington scene though. Feel free to stop by and check out the build - we break ground next week and will be going through framing of exterior shell till about the end of October if everything stays on schedule. Although I'm far from knowing what I'm doing, I"m stumbling along as best as I can. After that - I try to get the heat pump installed enough to keep my foundation from going below about 30 degrees F this winter since it's an alaskan slab.