John Sayers' Recording Studio Design Forum Archive

Aloha All!

My name is Paul. Thanks so much for this site! I’ve learned a ton on here and appreciate the resources, and for all of you for taking the time to help people like me :0) I’ve been wanting to finish up a basement area into a home theatre / studio. I’m a part time sound engineer, and part time owner / builder of my home, and after a decade of not creating any music it’s time to finish up my man cave so I can get back into composing!

The current space is small, but will be sufficient for me since most of my work is solo. 19’ L x 15’4” W x 10’4” H in the back, 8’ H in the front. I’m mostly using my computer and have several keyboards, bass, elec drums, congas, and sometimes invite female vocalists and studio musicians to add color to my electronic music. I love my subwoofer, so that’s where I’m hoping to tame the woof woof woof from wifee when I’m jamming at 2am! I listen to music in the 80-90 dB range. Currently, if it’s 80 dB inside the basement with only fiberglass R19 in the 2x6 walls, it’s 48 dB directly outside the French doors, so not too bad. Closest neighbor is 50-70 yards away, so I’m really looking to contain sound from travelling into the rest of the house as much as possible.

The current basement structure is built on a 8-10” concrete slab. Walls are 2x6’s 16OC with R19 insulation, and outside sheathed with 5/8” plywood and hardibacker cement boards that are all caulked together. The 10’4” ceiling joists on the back side of the space are 2x12’s. Directly above the 2x12’s is the kitchen. Subfloor is 1 1/8” T&G plywood with 5/8” travertine tile on top. In between the 2x12’s I’ve mounted 2 layers of 5/8” sheetrock with green glue to the subfloor then R30 Roxul. The ceiling towards the front are 2x8’s which slant downward to 8’ height at the French doors. I plan to put R19 in between these joists. Above this slanted roof is 5/8” plywood and tar roofing above which is a deck outside. I didn’t plan to put sheetrock in between these joists but I can if it’s recommended.

The plan is now to build a room inside a room with 2x4 walls and R13 insulation, with a minimum 2” space from the current walls, and 2x6 ceiling joists with R19 insulation, all with double 5/8” sheetrock and green glue. I’ve ordered 30sq ft of ½” 60A neoprene for under the base plates and around the windows. We have a nice view, so I’d like to try and retain the view from my workstation out the French doors and hopefully out the windows to the left. The door at the rear will be doubled (one exterior steel door and an inner wood door) and will be the main entrance. I plan to do a floating floor! (LOL not crazy the expensive kind!) Engineered oak veneer click track planks installed on top of 12mil cork underlayment :0)

Here’s where I need some advice please! I was planning to build a wall in between the two windows on the left, that would span across the entire front of the space (3.5' x 15'). This wall would have a center window to retain the view out the front French doors and will have a wooden entrance door on the right. I tried to sketch this in the sketchup program, and have a few pics attached. I have identified a few problem areas I need some help with from all of you that have experience in this area.

Q1. The first is the window on the left side that will remain inside the studio. I could eliminate it completely, though I’d rather have the view and cool air from it if possible (we live at 4000ft elevation so it’s quite cold here!). If I double the window with another identical one I think I create a quadruple leaf effect. Is there any way to moderate this effect yet keep the window? Maybe build a wooden door instead of adding another like window? Will this completely ruin all the other work I’m doing to contain sound? If I have to part with this window, so be it, tho I’d rather try and keep it if there’s a way.

Q2. Another issue is the wall in the front I want to build. This front 3.5' x 15' area can act as my vocal / instrument area and could help mitigate sound transmission out the front French doors. But If I want a clean look and I sheetrock the inside of this area too, I’m again creating a quadruple leaf effect, right? Is there maybe a material I can mount instead of sheetrock that would not create another leaf? I wouldn’t want my vocalists to leave itchy from the unenclosed walls with fiberglass insulation LOL! What about cork panels? Some type of heavy cloth? Wondering if any of you might have some suggestions to give that section a finished look yet not create another leaf?

Q3. There’s also a ventilation duct from the oven fan in the kitchen above. I know I need to box the area out in the double sheetrock/greenglue but wondering if it would help to first wrap it in something?

Q4. There’s also 1 bay in the 2x12’s above that contain a 3” pvc drain from the sink in the kitchen, as well as the hot and cold copper water pipes. The pipes are currently wrapped in the R30 Roxul, but I’ve read that some people enclose in between these two 2x12’s that contain pipes. My question is: is there a particular product I should use that won’t create a triple leaf effect, or is the 1 bay that’s enclosed in the original ceiling better than the sound transmission that will occur thru the pipes if it’s not enclosed?

Q5. My last question is in between the double doors / double windows. If I were to leave say a ¼” in between the jams and caulk the space with acoustical caulk would this be acceptable? I wasn’t totally clear in what to do here to get a finished look yet not connect the two walls :0( Any reference links please do forward!

Any other suggestions I’m open ears!

I estimate this project will cost me about $10000, not including acoustical treatments or any extra features inside.

I tried loading the 3D sketch file but didn't seem to take, so I exported and uploaded the 2D jpg version

Thanks so much in advance for your time!

This site has been a great learning experience for me :0)

Cheers,

Paul

Hi Paul, and Welcome to the forum!

The current space is small, but will be sufficient for me since most of my work is solo. 19’ L x 15’4” W x 10’4” H in the back, 8’ H in the front.

That's not too bad, actually. At nearly 300ft, that's quite good. From what you say, it sounds like this is going to ba a mulct-purpose room, for jamming, tracking, mixing, and home theater? That's a pretty tall order, with some rather different acoustic needs. You should probably prioritize what the MAIN purose of the room is going to be, treat it for that, but with variable acoustic panels that you can adjust to modify the acoustic response of the room as needed for those rather different scenarios. So what is the order of priority? Is this primarily a control room, for doing high quality mixes? Or is mixing not important, and Home Theater is the main event? Or perhaps jamming/tracking is the real purpose, with the others taking a back seat?

As long as you are aware that it is impossible to have one single treatment that works for all your scenarios, and that variable treatment is the only real way to cover all bases, that's fine, but even then you should line up your priorities from top to bottom, and design the treatment accordingly.

I love my subwoofer,

Brand? Model? Purpose? By that, I mean is it a home theater type sub, designed for shaking the walls in an earthquake movie, or colliding-galaxies movie, but without suitable response for a control room? Or is it a proper control room sub, with precision response? Once again, ... priorities....

I listen to music in the 80-90 dB range.

dBA or dBC? In other words, did you measure that level with your meter set to "A" weighting or "C weighting? There can be a massive difference.

Currently, if it’s 80 dB inside the basement with only fiberglass R19 in the 2x6 walls, it’s 48 dB directly outside the French doors, so not too bad.

So you are getting about 30 dB isolation? That's typical for a regular house wall. Fine for things like voices, radios, TVs and suchlike, but not so fine for acoustic drums at 3 AM....

I’m really looking to contain sound from travelling into the rest of the house as much as possible.

OK; but have you considered sound going the other way? Into the studio? You mentioned tracking vocals and some acoustic instruments, so you should also be taking into account potential structure-borne noise in the house getting into your mics, such as doors closing, people walking on floors, vacuum cleaner, water running in pipes, dryer, furnace, microwave, etc. Anything that makes a noise and might have a physical connection to the building structure. Also loud sounds outside, such as fire/police/ambulance sirens driving by, aircraft/helicopters flying overhead, rain/hail/wind/thunder, traffic on the street outside, dogs barking, lawnmower, etc.. If you are aiming for a studio where you can track anything at any time, then those are all potential issues.

The current basement structure is built on a 8-10” concrete slab.

Excellent!

Walls are 2x6’s 16OC with R19 insulation, and outside sheathed with 5/8” plywood and hardibacker cement boards that are all caulked together.

Excellent!

In between the 2x12’s I’ve mounted 2 layers of 5/8” sheetrock with green glue to the subfloor then R30 Roxul.

That's great, but did you get that checked by a structural engineer? That's a fair amount of extra dead load you added: it would be good to check that you are not overloading the floor above you. Probably OK; but better to check.

Above this slanted roof is 5/8” plywood and tar roofing above which is a deck outside. I didn’t plan to put sheetrock in between these joists but I can if it’s recommended.

What is your isolation goal? In decibels. That's a good starting point for studio design. Define how many dB of isolation you need, and design the system for that level.

The plan is now to build a room inside a room with 2x4 walls and R13 insulation, with a minimum 2” space from the current walls, and 2x6 ceiling joists with R19 insulation, all with double 5/8” sheetrock and green glue.

Once again, have you checked that with a structural engineer? I didn't check the math, but it seems to me that 2x6 joists spanning that distance with that load would not be safe.

I’ve ordered 30sq ft of ½” 60A neoprene for under the base plates

Why? Is your slab terribly uneven, and you need to get a good seal? Is that the reason?

We have a nice view, so I’d like to try and retain the view from my workstation out the French doors and hopefully out the windows to the left.

You can do that, yes, provided that you do not need much isolation. You cannot have operable french doors and windows, and still have good isolation. So your options here are: 1) live with poor isolation, and have a great view through operable doors/windows. 2) Seal up and double-up the doors and windows to have a great views and also good isolation. 3) Replace the doors/windows with suds and drywall, and have great isolation with no views.

The door at the rear will be doubled (one exterior steel door and an inner wood door) and will be the main entrance.

Why only that door? You said you plan to build a room-in-a-rooms studio, which implies that you have two leaves around the entire room, and therefore every doorway needs two doors, back-to-back, one in each leaf, and ditto for the windows. You can't have a two-leaf isolation system if there is only one leaf in some places. ALL doors need to be doubled-up. And also all windows.

I plan to do a floating floor! (LOL not crazy the expensive kind!)

Are you SURE about that? Have you read this thread? : http://www.johnlsayers.com/phpBB2/viewt ... f=2&t=8173

Here’s where I need some advice please! I was planning to build a wall in between the two windows on the left, that would span across the entire front of the space (3.5' x 15').

How does that wall fit into the "room-in-a-room" plan? Here's how to do an actual room-in-a-room for a single room studio: That's just the concept, of course: no details. But you get the idea. You have the outer leaf as a "shell" that completely encloses the inner-leaf, which is also a shell. Where would you you be putting that wall? If you need to divide the space into several rooms, then each room is built separately, as a single independent leaf, like this: You don't normally have walls within rooms.

Q1. The first is the window on the left side that will remain inside the studio.

If you like your window, you can keep your window! But with caveats...

though I’d rather have the view and cool air from it if possible

View? Sure, no problem. Air? Nope. You can't have operable windows in a studio if you also need good isolation. Sorry. And in any case, opening a window into a studio does not provide air flow into the room. The room will be sealed twice over, totally hermetic, so if you opened the window, nothing would happen. The air would just stay there. Air needs a difference in pressure in order to move, and just opening a window does not produce a pressure differential, like it would do in a typical house.

Also, that's not the way to deal with ventilation: even if you could open your window and somehow get a magical air flow through it, that's not an option while you are tracking, mixing, or jamming. Opening the window or door completely destroys the isolation. Presumably, you are building the studio in order to get good isolation, so it's pointless to do that if your ventilation plan is to destroy the isolation all the time, by opening doors and windows. HVAC is a huge part of studio design, and very necessary. It cannot be done with doors/windows, for many, many reasons.

If I double the window with another identical one I think I create a quadruple leaf effect.

Are you saying that the existing widow is already a double-glazed unit, with two pieces of glass in it? If that's the case, then you would NOT put a similar double-glazed unit in the inner-leaf window: Instead, you would just use a single-glazed unit that has a single pane of thick laminated glass. That will give you a 3-leaf system, yes, but if you do the calculations carefully, then you would still be able to match the isolation of the rest of the system.

Is there any way to moderate this effect yet keep the window?

You can keep the window, yes, and you can still have good isolation, yes... as long as you don't try to make that window operable...

Q2. Another issue is the wall in the front I want to build. This front 3.5' x 15' area can act as my vocal / instrument area and could help mitigate sound transmission out the front French doors.

See above diagrams: You can't build a wall inside a studio room, as it will not isolate much. If you need a vocal booth, then build a vocal booth! You do have enough space to do that. You could even divide the space into two, with one end being a proper control room for mixing well, and the other end being a small live room. But you do need to do it properly, if you want good isolation.

Is there maybe a material I can mount instead of sheetrock that would not create another leaf?

Paper? That's about the only thing that is light enough (low density) so as to not be a leaf. Of course, it would not isolate either....

There are no magical materials, unfortunately. The only way to stop sound is with mass. Lots of it. And that's what a leaf is! Mass.

I wouldn’t want my vocalists to leave itchy from the unenclosed walls with fiberglass insulation

I don't understand: Why would your vocalists be exposed to insulation? There's something here I'm not understanding. If you build a vocal booth properly, then they would not be directly exposed to insulation.

Wondering if any of you might have some suggestions to give that section a finished look yet not create another leaf?

Once again, I'm not getting what you are trying to say: there are MANY ways of finishing the interior surfaces of a room, and the method you choose will depend on the design concepts. If you build your walls conventionally, then you will have drywall facing the interior of every room, and you will then hang your acoustic treatment panels on that. If you build your walls "inside-out", then you will have the stud bays facing the room, and you willl build the acoustic treatment into the walls themselves, then cover that with fabric, or slats, or something else, as needed to get the acoustic response you need for each room.

Q3. There’s also a ventilation duct from the oven fan in the kitchen above. I know I need to box the area out in the double sheetrock/greenglue but wondering if it would help to first wrap it in something?

Depending on how it is done at present, you could possibly wrap the duct with suitable insulation, then wrap that with MLV and seal it up completely, then more insulation, then your drywall.

is there a particular product I should use that won’t create a triple leaf effect, or is the 1 bay that’s enclosed in the original ceiling better than the sound transmission that will occur thru the pipes if it’s not enclosed?

Unfortunately, if there are pipes/ducts in between your bays, you don't have a lot of choices: you are pretty much stuck with a 3-leaf system, so you have to design it to provide the isolation you need. In other words, you compensate for the 3-leaf effect in the design itself, by having the right amount of mass in each leaf, and the right size air gaps.

Q5. My last question is in between the double doors / double windows. If I were to leave say a ¼” in between the jams and caulk the space with acoustical caulk would this be acceptable?

If you build your studio correctly, there's no need to seal the gap between the leaves at windows and doors. Just cover it with fabric, to hide the "ugly".

I estimate this project will cost me about $10000, not including acoustical treatments or any extra features inside.

The total cost will probably be higher than that. A good rule-of-thumb is to allow about US$ 50-70 per square foot for a simple studio build in an existing building, and about double that for a complete build from the ground up. So you are probably looking at somewhere in the region 15k to 20k, realistically. More if you have multiple rooms with independent HVAC. More still if one of the rooms is a high quality control room.

I tried loading the 3D sketch file but didn't seem to take, so I exported and uploaded the 2D jpg version

Use a file-sharing service, such as Dropbox, and post the link here.

- Stuart -

Stuart,

Thank you for the quick reply! :0)

The Primary purpose is definitely 80% control room for high quality mixing, composition. The theater 15%, and vocals / instrument recording 5%. I could probably get by with recording just in the control room.

My subwoofer is a Mackie HRS120, with 4 Mackie HR624 monitors - not the greatest but it served it's purpose on my first album. I will probably save for an upgraded set that's more accurate and higher quality once everything is finished :0)

I used dBA and slow response when I measured the sound outside my french doors. would be nice to get a 60-70dB reduction when finished. What do you think the typical reduction is with a properly built double sheetrock inner room with green glue?

We totally overbuilt the home, so no worries on adding double sheetrock in between the ceiling joists :0)

I agree that I should think about sound transmission into the studio also - mostly from my dog - he's a big boy with a big bark!! I'm sure he will ruin a few tracks every now and then LOL

The ceiling will have a header in the middle, so the 2x6's will span at most 8ft on each side of the studio, well within code :0)

Regarding the neoprene, since my inner room will be directly on the concrete slab, same as the outer walls, I've read neoprene is a better medium than the standard $5 foam to help reduce transmission thru the concrete. Is that not the case? I'll need a moisture barrier under the 2x4 wall anyway

I think I will eliminate the windows on the side but not my view out the doors. I feel more creative keeping the view, and am ok if it's not as much isolation.

Sorry I've confused you about the front wall - I'll upload another sketchup of my room in a room thoughts that will hopefully clarify. The questions I had were referring to the wall of the inner room in room that runs parallel to the french doors. I think this is similar to the pic you posted for me with the 3 room in rooms and a corridor on one side. What if the corridor was lined with a cloth instead of sheetrock? Would that eliminate the third leaf? Would that be better?

Since my french doors open inward, I will also have a "corridor" in the front. It's this entryway, or corridor, that I'm wondering if it the walls can be lined with cloth or something other than sheetrock to not create another leaf but still have a nice finished look? In the attached sketchup the inside walls of the outer shell are pink like the current insulation I have. The outside walls of the inner shell are also pink for insulation.


Thanks again for the advice!!

Cheers,

Paul

The Primary purpose is definitely 80% control room for high quality mixing, composition.

Great! That sets a lot of things in place already, including overall acoustic response. Basically, the goal is to get close to the "critical listening room" specs, as laid out in documents such as ITU BS.1116-3 and EBU Tech-3276. If you don't have those, then google them and download them. The relevant part is chapters 7 and 8 of BS-1116 (the rest doesn't pertain to recording studios).

So, next step: If it's going to be a high-quality control room, then you should define which basic design concept you plan to use. There are several, and personally I almost always use the RFZ style, since it gives the best results. But there are others.

I will probably save for an upgraded set that's more accurate and higher quality once everything is finished :0)

That's actually kinda backwards! That would be sort of like deciding what car to get after you already bought the tires and floor mats... (Maybe I exaggerate, just a little...) The speakers are the reason why the studio even exists: if you didn't have speakers, there would be no need at all for a control room! So the normal process is to design the room around the speakers. Many things about the room will be affected by the choice of speakers. For example, if your speakers have very wide dispersion, then you would need to treat the side walls differently from they way it would be done with speakers having narrower dispersion. If the speakers happen to be unusually deep, then you'd need to accommodate that in the design. Etc. So it's best to start of by deciding on what speakers you will use (even if you don't have them yet), and design the room for those.

I used dBA and slow response when I measured the sound outside my french doors.

You should use dBC for studio measurements. dBA is meant more for quiet sounds of a general nature, as it closely resembles human hearing response to low level sounds. dBC approximates the way human ears perceive loud, broad-spectrum sounds, such as music. dBC is more sensitive to low frequencies that dBA, and there can be a large difference. At a rock concert, you might measure 110 dBC but then when you flip the meter to dBA it shows only 95 dBA....

So you should repeat your measurements with the meter set to "C" weighting.

would be nice to get a 60-70dB reduction when finished.

That's possible, but it's pretty much the limit for what can be achieved in a home studio.... assuming you are willing to invest a LOT of money in isolation! The decibel scale is logarithmic, so large numbers mean very large budgets. It's dead easy to get an increase of 10 dB in isolation at the low end, but extremely hard to get an increase of 10 dB in isolation at the high end. So if you have a wall that isolates 20 dB, improving that by 10 to get 30 dB is a piece of cake, and will only cost you a couple of hundred dollars, tios. But if you have 60 dB isolation and want to increase it by 10 dB to 70 dB, then you better have very deep pockets, because that's going to set you back many tens of thousands of dollars. 70 dB is pretty much as good as you can get for home studios, as that's roughly the flanking limit of typical construction on a concrete slab.

What do you think the typical reduction is with a properly built double sheetrock inner room with green glue?

That depends on several factors, but around 60 dB would be a good estimate.

The ceiling will have a header in the middle,

Your inner-leaf ceiling will have a beam running across the middle? That will take up quite a bit of space, which reduces your head-room, potentially. How will that be supported at the ends? It cannot touch the outer leaf at any point, so it will need some pretty sturdy posts at each end, likely sunk into their own foundations, to support it. It will also need some type of diagonal bracing, since it has to be free-standing. Seems like a lot of expense and complication, when you could just use larger joists and span the whole room more easily.

so the 2x6's will span at most 8ft on each side of the studio, well within code

For what load? Depending on the type of wood, the deflection, and the load, it's possible you could need 2x8's even for that distance...

I've read neoprene is a better medium than the standard $5 foam to help reduce transmission thru the concrete. Is that not the case?

Not really. You are building on a slab-on-grade base, which implies that your slab is damped by the entire planet Earth... That's hard to beat! Most home studio builders just bolt their inner-leaf walls to the slab. Unless there's some type of impact noise getting into the slab, it usually isn't necessary to do more than that.

Besides, putting a strip of rubber under your sole plate does not actually decouple the wall from the floor anyway: you still have to anchor the wall to the slab with steel bolts, which create major flanking paths that totally bypass the rubber.

I'll need a moisture barrier under the 2x4 wall anyway

If you have a moisture problem with your slab, you should get that fixed first! You can't build a studio on a slab that has a moisture issue. You better get an expert in to take a look at why your slab is not dry, and advise you on your options.

I think I will eliminate the windows on the side but not my view out the doors.

That will make it easier to treat the side walls as well.

Sorry I've confused you about the front wall - I'll upload another sketchup of my room in a room thoughts that will hopefully clarify

That clarifies what you mean, yes, but unfortunately you can't do it like that: you cannot have a room inside your wall cavity! You would need another wall across there, just beyond the left side inner-leaf wall (with the window in it), and that would complete the outer-leaf "shell".

What if the corridor was lined with a cloth instead of sheetrock? Would that eliminate the third leaf? Would that be better?

Why have a wall at all, if it is only studs with fabric on one side? That won't do anything, except provide a visual barrier. A wall without drywall isn't a wall at all: it's just a frame.

Since my french doors open inward

As I said in the first response, you can't have operable double-doors in a studio. There's just too many issues with trying to get a good seal each time you open and close that, and there's not nearly enough mass in the typical thin glass that is used on ordinary french doors. Like i mentioned, if you want to keep those French doors as sealed windows, that's fine, but they will need to be fixed permanently in place and completely sealed. You say you want very high isolation, so you don't have any other options there. If your studio is not double-sealed, absolutely hermetically air-tight on both leaves, then you can't get good isolation.

In the attached sketchup the inside walls of the outer shell are pink like the current insulation I have. The outside walls of the inner shell are also pink for insulation.

What you are showing in pink is, indeed, the insulation in the wall cavity. In addition to that, there is sheathing on only one side of the studs, for both leaves. You are showing that your corridor is contained inside your wall cavity, between the inner and outer leaf. You can't do that, unfortunately. Where does that corridor lead to?



- Stuart -

Hey Stuart,

Just got back from a nice trip to Napa with wifee :0)

Now back to my project!

I've returned the neoprene to home depot, and got my $350 credit!

Regarding the moisture barrier, the base plates, or sill plates do all have a foam barrier between the cement foundation and the base plate of all the walls. Instead of the neoprene I will just use the same foam we installed throughout the rest of the house. There isn't moisture in the foundation, but these do supposedly help better preserve the wood, provide a better seal, and prevent bugs and such from entering

I re-measured with dBC and seems to increase the reading both inside and outside equally about 7dB's.

I've taken your advice and removed the side window in the studio space, and boarded it up and sided it, and insulated the inside walls!

I've also decided to add the additional wall in the front that you suggested. I'll now have two 2x4 walls separated by an inch or so. The inner wall on the control room side will have the thicker glass (1/2") for the center viewing window, and the outer wall 1/4" glass.

First question - With double 5/8" sheetrock on all the inner walls is that thickness glass acceptable?

Second Question - do I need to angle these windows or just leave them parallel to each other? I've read some conflicting info on that....

Third question - By adding the 2 walls in the front, my control room space essentially goes from a rectangle (19' x 15' outer shell) to a square 14'6" x 14'9' control room. I know it's not optimal to be square, so I'm wondering if it would be beneficial to move in the side walls in to make it back to a rectangle?

regarding the duct I have to deal with - with the room square now, by moving the side wall(s) in 2 ft or by angling the walls in toward the front creating a trapezoid shape control room I could get the duct to the space in between the walls instead of building an ugly box around it. (see sketchup pics please).
Fourth question - Is a trapezoid shape without the duct better than having a square shape with a duct sticking out (obviously it would be framed and double sheet rocked, for the control room? It sticks out from the top middle of the left side wall about 2 feet and hangs down about another 2 feet. I've circled it in the attached pic below.



Thanks in advance!

Cheers,

Paul