Basement Studio Construction in Boston, MA, USA

Hi all, My name is Chris – first time poster living in the Boston, MA, USA area. Thanks very much for this forum, I apologize in advance if I’ve missed any of the rules for posting. I am in the process of constructing a small basement recording studio in my home, which will be broken up into a control room and a live tracking room. I have included a sketchup of the current state of the basement with dimensions. I live in a densely populated suburb, so my neighbors are only 20’ away on one side and 60’ feet away on the other. I will be playing and recording many types of rock music with live acoustic drums, guitar, bass, and keys/organs. My assumption is that the sound level will be upwards of 120db in the tracking area, and I would like to reduce it to around 40/50 db outside. Although, I realize that may be a lofty goal. My walls: My foundation is mostly exposed stone/rock, but poured concrete sits on top of the exposed rock. This will be my outer leaf, and the walls are about 6” thick. If I leave 4" of air space from the foundation to the 2X4 stud framing, should I stagger the studs on a 2X6, or will that create a three leaf system? Either way, I intend to put insulation between the studs. I get the feeling that this forum doesn’t feel that the more expensive insulation (like Roxul’s Safe and Sound), is actually much better than the more affordable insulation. Can you please recommend some of the better products for insulation, which are available in the US or Northeast US? Just to clarify – After the foundation will be 4" of air gap. Then my framing will begin (either staggered studs on a 2X6 or standard studs on a 2X4), which will be filled with insulation and then foam board sound proofing will be attached to the inner layer of the studs, and drywall will be attached (probably glued) to the foam board. Does this sound like the correct process? Is it better to do one layer of foam board, then one layer of drywall, then another layer of foam board, then another layer of drywall, all glued together (maybe with Green Glue)? I realize that it is desirable to have multiple densities to increase sound proofing and isolation. Can you recommend what type of sound proofing (foam board, etc.) and at what thicknesses should be put on the inside edge of the studs on top of the insulation? Also, do you have an opinion about gypsum boards/drywall like Silentfx, Quietrock, and/or Soundbreak, which all claim to increase sound proofing? They look about the same to me, so any advice would help. If I was to use cloth panels and/or black cloth in the tracking area within the inner leaf walls instead of drywall, would that provide as much sound isolation as drywall? It seems like the lack of mass from cloth would make it a bad choice for isolation, but I see it in a lot of fantastic studio designs, (including John's). Please advise. The Ceiling: Unfortunately, the ceiling rafters are only 6’9” off the concrete floor in the tracking area and about 6’7” off the concrete floor in the control room. Therefore, I will not be able to have an air space (spring) from the ceiling rafters to the drywall on the ceiling, because of lack of room height. In other words, the ceiling will not be completely isolated. I intend to fill the ceiling rafters (8” deep) with insulation, then to add a layer of some type of sound proofing and a layer of 5/8 sheet rock. From the bottom of the rafters to the bottom of the sheet rock can’t be more than 3-5" for room height. Is there a good type of sound proofing and/or drywall that will maintain mass and isolation but not lose too much headroom? If so, do you have an opinion on Audimute’s product called Peacemaker? It claims to act as another resilient channel but is only 6.4mm (1/4”) thick. I understand that using a Resilient Channel (metal frame) will help with isolation. Can you please explain exactly how that should be done? Do I attach the sound proofing material (foam board or whatever) into the metal channel and then glue/nail the drywall to that? Does it matter how the metal channel is attached to the inner leaf walls, which are 2X4 studs? Should they be screwed to the top or side of the frame, and should it not touch the sound proofing/drywall on the inner leaf walls? On to room treatments: Is there a preferred angle for bass traps in tracking and control rooms? I will be using REW to determine the room modes, etc., when the construction is finished, but I’d like to be able to build the bass traps during framing. Also, when designing the bass traps and acoustical treatments for the control room, is there an easy way to determine the angle and slope at which the sound will leave the studio monitors? I’ve tried to determine it with the protractor in sketchup, but I don’t believe I am doing it correctly. As for electrical wiring, I’m wondering about grounding. I have one circuit breaker panel for my basement and first floor, and my electrician has told me that he can give me 8 additional circuit breakers within that same panel for my studio needs. I will separate the outlets in the tracking room, the control room, and for the lighting and refrigerator on to separate circuit breakers, but if they are all tied to the same panel, which I believe has only one ground (earth), am I not essentially using the same ground for everything? My electrician believes that as long as the ground (earth) is well done, it should not be a problem, but I would like to hear your input. Again, thanks very much for this forum. It has been immensely helpful already. I appreciate any advice in the future! Best, Chris

Just an update - this is my current design for the studio. As you'll see, it's John's control room design from here: viewtopic.php?f=1&t=5457, and his vocal booth design from here: viewtopic.php?f=1&t=14147, but without the aircon ducts. Both sketchups have been re-sized to fit in my basement. I realize that I'll be losing a lot of space in the control room by using this design, so if anyone has any other thoughts, I'd love to hear them. Again, the walls will be an MSM system, with the concrete walls as the outer leaf. The inner leaf will be 2X4 studs w/ insulation, then a layer of sound board, then a layer of 5/8 sheet rock. The ceiling will also be sound board and 5/8 sheet rock suspended from the existing ceiling joists by resilient channel. Inside the floor joists will also be insulation. I've gotten two quotes so far for my resilient channel, insulation, foam board, and drywall. They recommended RC1 for Resilient channel, "Sound Deadening Board" in 1/2"X4X8 sizes for foam/sound board, 5/8 sheet rock, and "Sound Attenuation Blankets" for insulation, which comes in 3"X16"x48" batts. All told, they will deliver 40 12' lengths of RC1, 61 4x8 sheets of Sound Deadening board, 61 4X8 sheets of 5/8 sheet rock, and 27 bundles of sound insulation for about $2,100. Any thoughts on those products and that price? Thanks again for your input. Best, Chris

Hi Chris, and welcome! :)

My assumption is that the sound level will be upwards of 120db in the tracking area, and I would like to reduce it to around 40/50 db outside. Although, I realize that may be a lofty goal.

Yep! :) 50 dB reduction is fairly easily attainable, 60 dB a lot harder, 70 dB extremely hard (not to mention expensive), but 80 dB is probably off the table, unless you have really deep pockets. The decibel scale is logarithmic, so each time you go up 10 dB, you are talking about ten times the intensity, meaning it is ten times harder to do. So 70 dB isolation is a hundred times harder than 50 dB, and 80 dB is one thousand times harder... So it might be feasible to hit your goal of 50 dB outside, but I'd say that 40 dB is probably not in the running. Having said that, a level of 50 dB outside is probably pretty close to the ambient level anyway for a residential area, so you are probably fine with that.

My foundation is mostly exposed stone/rock, but poured concrete sits on top of the exposed rock

That's a good start!

and the walls are about 6” thick

So all four walls are 6" solid concrete over a rock base? And the floor? What about the ceiling?

If I leave 4" of air space from the foundation to the 2X4 stud framing,

Do you mean "four inch air gap" or "four inches between the wall and the studs"? That's not the same thing. A 4" gap to the framing implies a 7-1/2" air space.

stagger the studs on a 2X6, or will that create a three leaf system?

It would only be 3-leaf if you put drywall on both sides of the framing. If you just do it on side, then that plus your concrete/rock/stone walls is a two-leaf system, which is what you want. But for that, you don't need 6" studs, and you don't need staggered. Just do a normal 2x4 stud frame, with drywall on only ONE side.

Either way, I intend to put insulation between the studs

For that level of isolation, I would fill the entire wall cavity with insulation. Or fill as much as your local fire code allows.

I get the feeling that this forum doesn’t feel that the more expensive insulation (like Roxul’s Safe and Sound), is actually much better than the more affordable insulation. Can you please recommend some of the better products for insulation, which are available in the US or Northeast US

Price is irrelevant: what matters is density. If you use fiberglass insulation, then the optimum density is 30 kg/m3. If you use mineral wool insulation, then the optimum density is 50 kg/m3. So regardless of brand names or model numbers, what you should be looking at most is the density.

Just to clarify – After the foundation will be 4" of air gap. Then my framing will begin

OK, so that answers my question above! So its a 4" gap to the framing, implying a 7-1/2" air space.

foam board sound proofing will be attached to the inner layer of the studs

I'm not familiar with "foam board sound proofing". Do you have a link to that? But it most likely isn't needed. what you need is very large amounts of mass. You already have that on your outer leaf (the concrete/rock/stone), but you also need something substantial for the inner-leaf. 5/8" drywall is a good option. So are thick fiber-cement panels, OSB, MDF and plywood.

and drywall will be attached (probably glued) to the foam board.

:shock: :!: You cannot glue one layer of your leaf to an underlying layer! Each layer MUST be nailed directly into the studs, regardless of how many layers you use. So each subsequent layer needs nails that are longer than the ones you used on the previous layer by the thickness of that layer. The nails on each layer must penetrate all the way into the studs.

all glued together (maybe with Green Glue)?

Green Glue is not an adhesive (despite the name) and cannot be used to glue anything to anything else. Green Glue is a constrained layer damping product, in the form of a visco-elastic substance that never hardens. It is an acoustic product that helps improve low-frequency isolation, not a structural product.

Does this sound like the correct process?

:) see above...

I realize that it is desirable to have multiple densities to increase sound proofing and isolation.

Welll... yes and no. That's a common misconception. Yes, it does help to vary the density or thickness of the layers, but the effect is only small, and is much less than the effect of having the highest density and greatest thickness on ever layer. What you gain from the "variation" in thickness / density, you lose to a much greater extent by not having maximized mass, thickness and stiffness (rigidity). That said, for structural reasons it is sometimes recommended to do the first layer with structural OSB or plywood, then do subsequent layers with 5/8" fire-rated drywall, possibly using Green Glue in between if you can justify the cost.

Also, do you have an opinion about gypsum boards/drywall like Silentfx, Quietrock, and/or Soundbreak, which all claim to increase sound proofing? They look about the same to me, so any advice would help.

Think of it this way: All products must obey the laws of physics: there are no magical materials. Sound waves can't read the price tags, and aren't snobbish anyway, so they really don't care how much you paid for your materials. what they react to is purely one thing: mass. As in kilograms, pounds, tons, stones, carats, grains or hundredweights. That's all they care about: how much mass you put in front of them. So it simply makes sense to buy the least expensive mass that will do the job. Generally, in most places that is plain old fire-rated drywall. In some cities / counties / countries it might turn out to be wood, or brick, or fibercement, or something else. But whatever it is, get the mass that costs the least (unless you have a huge budget, and don't mind wasting money! :) ).

If I was to use cloth panels and/or black cloth in the tracking area within the inner leaf walls instead of drywall, would that provide as much sound isolation as drywall?

Mass is what stops sound waves, nothing else. (Or rather, nothing else that is practical in real life.) Drywall has lots of mass. Cloth has no mass at all.

It seems like the lack of mass from cloth would make it a bad choice for isolation,

Exactly right! No mas = no isolation.

but I see it in a lot of fantastic studio designs, (including John's). Please advise.

The cloth you see in those is covering up the acoustic treatment inside the finished rooms. It has nothing at all to do with the isolation of the room. Isolation and treatment are two totally different and entirely unrelated aspects of studio building. Isolation stops sound getting out, which means it has to stay in. Since it stays in, it has to bounce around inside the room indefinitely ("reverberating"), slowly dying away due to the natural attenuation of air. But that sounds terrible! You can't track or mix in a reverberant room. That's where acoustic treatment comes in: it is what you do to the finished isolated room to make it sound good again. But most types of acoustic treatment are pretty ugly, so the get covered up with cloth.

Unfortunately, the ceiling rafters are only 6’9” off the concrete floor in the tracking area and about 6’7” off the concrete floor in the control room.

Ouch. That is bad news in deed. Very bad.

Therefore, I will not be able to have an air space (spring) from the ceiling rafters to the drywall on the ceiling, because of lack of room height. In other words, the ceiling will not be completely isolated.

So your goal of 70 to 80 dB of isolation is definitely and totally shot out of the water! Very little chance of getting close to that. Sorry.

then to add a layer of some type of sound proofing and a layer of 5/8 sheet rock.

The 5/8" sheet rock (drywall) IS the sound proofing! There's nothing you can add to that to soundproof even more, except another layer of 5/8" drywall.... Mass is what "soundproofs".

From the bottom of the rafters to the bottom of the sheet rock can’t be more than 3-5" for room height. Is there a good type of sound proofing and/or drywall that will maintain mass and isolation but not lose too much headroom?

5" for the isolation alone would place the final finished treated ceiling height at under 6 feet, probably around 5'10". Are you sure that's what you want? But you don't need to lose that much: RSIC clips plus hat channel works out to about 1-5/8" thick. Two layers of 5/8" drywall add up to another 1-1/4". Total thickness: 3-7/8". Or substitute 1/2" fibercement board for one of those layers of drywall, and shave off 1/8". Or do both layers with 1/2" fibercement, and attach the RSIC clips to blocking alongside the joists, raised up 1-1/4", and you can have your inner-leaf ceiling just 1-1/4" below the bottom edge of the joists... Or get the same height by ditching the clips and hat channel entirely, and supporting the inner-leaf ceiling on the inner-leaf walls, and interleaving the new joists between the old. There are several such techniques that can be used to minimize the loss of ceiling height.

I understand that using a Resilient Channel (metal frame) will help with isolation. Can you please explain exactly how that should be done?

You nail the RC to joists above, crosswise (perpendicular to the joists). You screw the drywall into the RC, taking great care that the screws do not go into the studs, only into the RC. Then you seal the joints in the drywall, and add a second layer, staggering the joints, also screwing carefully into the RC, not the studs, with longer screws. And a third layer, if you use the type of RC and mounting that can handle it.

Does it matter how the metal channel is attached to the inner leaf walls,

Walls? What walls??? I thought we were talking about the ceiling! The RC does not go anywhere near the walls. It is attached ONLY to the joists above.

Is there a preferred angle for bass traps in tracking and control rooms?

45° is generally the best, and the easiest. Especially of you do superchunk traps: 45 angles with 24" edges means you can cut the 4' x 8' sheets to not waste anything at all.

but I’d like to be able to build the bass traps during framing.

Ummmm... you can't! Bass traps go inside the room, so the drywall has to be in place already before you can build them. Even if you build your walls inside-out, you still can't do the bass traps until the walls are up.

is there an easy way to determine the angle and slope at which the sound will leave the studio monitors?

The manufacturer of your speakers should be able to tell you that. Most good studio monitors provide that information in the manual, in the form of polar plots or dispersion graphs. What speakers are you planning to use?

but if they are all tied to the same panel, which I believe has only one ground (earth), am I not essentially using the same ground for everything?

Exactly. You have to. Your building code probably requires a single ground for the entire building, so there's no getting around that, and no need to. as long as you do start-grounding inside your studio, and have a really good grounding grid for the building, then you are fine.

My electrician believes that as long as the ground (earth) is well done, it should not be a problem, but I would like to hear your input.

Right, but it MUST be star-grounded. Make sure your electrician understands that, and wires it correctly.

this is my current design for the studio.

You seem to be wasting a lot of space by splaying the entire side wall of your control room like that. As long as you splay the front half, you should be OK. From there on back the side walls can be parallel. - Stuart -

Hi Stuart, Thank you so much for your reply. I must admit, I was very impressed to get such a detailed and prompt response. I really appreciate it! As for your questions... ...So all four walls are 6" solid concrete over a rock base? And the floor? What about the ceiling?... Yes, all four walls are approximately that thick. The floor is also poured concrete, and the ceiling is just rafters at this point. I'm planning to cover the concrete floor with epoxy to reduce moisture and for color. Any thoughts on this? Here's the link to the product: http://www.lowes.com/pd_293613-4-024.00 ... facetInfo= If that link doesn't work, it might come up if you google, "garage epoxy kit". ...the optimum density is 30 kg/m3. If you use mineral wool insulation, then the optimum density is 50 kg/m3"... Is this the minimum density, or the optimum density? In other words, "Roxul Comfortboard FS", which is actually stone wool insulation, is 70 kg/m3. I've included a link to it: http://www.roxul.com/products/residenti ... rtboard+fs ... Would that work for my needs? That being said, I can't actually find any fiberglass insulation that is exactly 30 kg/m3, or mineral wool that is 50 kg/m3. Can you recommend any specific brands? ...That's all they care about: how much mass you put in front of them. Generally, in most places that is plain old fire-rated drywall... Just so I understand, I want to maximize mass, which in turn means maximizing density, correct? In other words, I want to find the densest, most affordable drywall. If I can afford a second layer of drywall, it would be nailed right on top of the first layer of drywall in to the studs. Right? ...Walls? What walls??? I thought we were talking about the ceiling! The RC does not go anywhere near the walls. It is attached ONLY to the joists above... Ok, but how do the walls connect to the ceiling to be sealed? Maybe I'm missing something that my contractor will understand, but is there a trick to sealing the walls and ceiling with a resilient channel? ...As long as you splay the front half, you should be OK... Can you expand on that a bit more? I'm not sure that I understand how to splay the walls correctly. Does it not matter the angle at which the walls are splayed? Thanks so much for all your help. I couldn't appreciate it more! Best, Chris Leary

I'm planning to cover the concrete floor with epoxy to reduce moisture and for color. Any thoughts on this? Here's the link to the product:

I've never used that product specifically, but the concept is fine. However, before you seal, you should check to see if you currently have a moisture problem. If so, then you need to get that fixed BEFORE you seal the floor. If not, then you are just trapping a potential problem in place...

Is this the minimum density, or the optimum density?

Optimum density, with a fairly broad range either side. It's not too critical as long as you don't go up to twice as dense, or half as dense, or heading in that direction...

Just so I understand, I want to maximize mass, which in turn means maximizing density, correct?

Weeeelll.... sort of! What really matters is the surface density, in terms of how many kilograms does each square meter of the wall weight (kg/m2) You can obtain that with thicker materials of lower density, or thinnner materials of higher density. For example, steel is about ten times more dense than drywall, so you could use 1/16" steel plate instead of 5/8" drywall, and lead is about 17 times more dense, so you could use lead foil just 1/32" thick, to get the same amount of isolation as a sheet of 5/8" drywall. But then the issue becomes cost, not density... :) The idea is to figure out how much surface density you need, then buy the least expensive material that will do the job.

In other words, I want to find the densest, most affordable drywall.

Right! And in most parts of the world, that is plain old 5/8" fire-rated drywall.

If I can afford a second layer of drywall, it would be nailed right on top of the first layer of drywall in to the studs. Right?

Exactly! And you can improve your isolation even further by putting a layer of Green Glue between those two layers (Despite the name, Green Glue is not actually glue: it is an acoustic damping compound. But it is green, at least, so they got the name half right! :)

Ok, but how do the walls connect to the ceiling to be sealed? Maybe I'm missing something that my contractor will understand, but is there a trick to sealing the walls and ceiling with a resilient channel?

Leave a gap around the edge of the ceiling drywall, of maybe 1/8" to 1/4", all the way around, so there is no contact. Then put in backer rod of the right size, to create one seal, push it in deep (1/2"), then fill that gap with acoustic sealant or non-hardening flexible caulk.

Can you expand on that a bit more? I'm not sure that I understand how to splay the walls correctly. Does it not matter the angle at which the walls are splayed?

The angle does matter, depending on what you are trying to accomplish. If you are looking to eliminate flutter echo, then 6° per side is about right (total 12°). However, flutter echo can be dealt with in other ways, so you don't need to angle the entire wall to do that. But if you are looking to follow the RFZ concept of studio design, then the side walls need to be angled correctly to keep the first reflections away form the mix position, and the way to figure out what angle you need, is by ray-tracing. But it will almost certainly be far greater than 6°. So, since you need to angle that part of the wall that affects the mix position at a greater angle, and since the rest doesn't matter, then you can angle ONLY the part of wall that actually affects RFZ, leave the rest parallel, and treat it for flutter echo. You gain a lot of space inside the room like that. - Stuart - Assuming you do the walls first, take the drywall on those up a bit lower than where the top surface of the ceiling drywall will be