John Sayers' Recording Studio Design Forum Archive

I have checked out a few companies. I have decided that I am going to use it on an existing wall then 1" x 1" strips of wood attached to the barrier sheet then put Homasote sheetrock over the wood flanks to help break the waves. I am looking for the best and maybe cheapest vinyl barrier I can find. My end goal is to create two rooms (10' x 8' with 8' ceiling) isolated from one another and also something I can tear down if we need to move in the future. One room will be used as a drum tracking room, the other a control/monitoring room. Until I can get the money for a complete studio rebuild this will have to do. I have heard that the vinyl barrier type of material is pretty effective for existing walls. Any other ideas for cheap effective construction/materials would be helpful.

Thanks,

Keith

Sounds like you need to read the "sticky" titled "complete section", to find out what works for wall construction - you seem to be headed for multi-leaf construction with inadequate materials, especially if you're trying for sound isolation.

2 mass, with one air space between. Anything else is VERY inefficient use of materials for isolation. Sheet rock is the cheapest, best mass you can get for building sound walls, period. Unless you live in a place where bricks are $.02 apiece, that is. Homasote basically just takes up space that could be utilized by higher mass, cheaper sheet rock .

If you want to know more, you can start by reading the stickies at the top of the forum - there's a lot of good info there, even though it takes a while to wade through it. Then, we can talk about why two identical rooms, each with two dimensions equal, isn't a good idea (unless it's already that way and you're stuck with it -

I'm not trying to tell you what you HAVE to do, obviously that's dumb as well as arrogant. However, I don't think you would be very happy after doing what you said you would; there are better/cheaper ways to get there...

Let me know what you think, maybe post a drawing of your proposed floor plan, and we should be able to help you come up with a workable plan... Steve

Steve,

Thanks for the tips. I read through the sticky (complete section). I realize my idea is wrong for what I am trying to do. I have re-vamped the sizes, before they were only general. I am attaching an image of the existing rooms. I am "stuck" with using the standard wall and can only enhance it for now to increase isolation. I cannot build the much prefered double wall senario and am looking to get the most enhancement from the walls that I have. It looks like the best idea will be to glue on another layer of 5/8" sheetrock or two to existing drum side of the wall. Then maybe do the same to the ceiling. I am assuming from the sticky that an RC is only effective when attached to the studs. If worst comes to worst I may be able to pull down existing sheet rock on one side(drum side) and insulate (703?), vinyl barrier it and RC it then put a couple layers of 5/8" sheetrock on it. Of course using Acoustical sealant will be required all around. Am I competely lost? How can I best isolate a standard construction interior wall. I have been tracking in the control room with the drums about a foot behind my listening position, so anything I do to move them to the other room is better than what I have now. One day I will have the cash to get a real design and construct it properly. For now this is what I am subject to.

p.s. I will also need to address the windows and wall facing the street. I am currently reading other threads on this now.

Any thoughts and/or ideas appreciated.

Keith

"It looks like the best idea will be to glue on another layer of 5/8" sheetrock or two to existing drum side of the wall." - Gluing successive layers together causes them to act as one layer, which lowers their resonant frequency (a good thing) but it also causes them to have only one critical frequency (not a good thing) - the general concensus on fastening subsequent layers now is to just screw them on, caulking each screw dimple as you go (or mudding them) - if doing new construction, or stripping down to studs and starting over, then the first layer can be fastened with screws twice as far apart (in order to lessen flanking through the fasteners and into the frame) - same with a second layer, if there will be a third - either way, the normal fastener spacing should be used on the last layer.

You're right, RC is worse than a waste of time if you can't put it directly on the studs - otherwise, you end up with a triple leaf system, which hurts wall performance rather than help it.

"How can I best isolate a standard construction interior wall" - If you can't remove the existing drywall but only add, you're limited in what you can do. If you put extra layers on both sides, you get some improvement but are limited by the coupling between leaves caused by shared studs. A standard 2x4 wall using 5/8 sheet rock, one layer per side, and WELL sealed, has an STC of around 40-41 dB - adding an extra layer to only one side raises that to STC 45, adding an extra layer to BOTH sides raises it to STC 48 - moving one of the layers to the other side of the wall, so that there were one layer on one side and three on the other, you still get STC 48 - the difference is that this makes the 3-layer side stiffer, which has the two-edged sword effect - a stiffer wall improves low bass blocking, consequently WORSENING bass absorption inside the room.

This means that, ideally, if you were to add 2 more layers of sheet rock to your walls, they should ALL be OUTSIDE the room for best results. Otherwise, you'll need more bass trapping than usual to get a balanced sound inside the room after sound isolation work.

Another gain to be had on the wall between rooms - if you go as far as to remove the wallboard on one side, you will have access to insulate the wall - doing that, plus using RC, would give you around 3 to 5 STC points improvement just from the insulation, plus another 5-6 points due to the RC - the combination would be well worth the effort IMO.

Hope this helps... Steve

Steve, you could not have answered my question more completely. Great comments! I appreciate you taking the time to review my situation.

A few more specifics--- Now, If I decide to take the existing sheetrock off, I am guessing that the best method would be to insulate with the best material available (703)? Then put RC, then two layers of 5/8" sheetrock on the drum side wall. Then go round to the other side and add a layer of 5/8" sheetrock to the control room side. Yes? or No?

Control room window. 1/2" glass on one side and 3/8" on the other with a slight splay of around 6 degrees or so. Laminate or regular glass?

Windows on the street side. cover ecisting with "blanket" material like this? www.allnoisecontrol.com/products/AcousticBlanket.cfm
Or something like glass it in with a second layer of glass and framing?

Ceiling. Vinyl Barrier? Or some other such product. Or RC and sheetrock again like the wall?

Thanks again for your wisdom, very cool.


Keith

"I am guessing that the best method would be to insulate with the best material available (703)? Then put RC, then two layers of 5/8" sheetrock on the drum side wall. Then go round to the other side and add a layer of 5/8" sheetrock to the control room side. Yes? or No?" -

Not quite, but close - studies have found that the best AVERAGE sound reduction is with 2-5 to 3 PCF density insulation in walls - this is based on "normal" conditions, not drums - deviating from this density figure toward denser insulation (higher PCF) improves high frequency isolation but worsens low frequency isolation. Going LOWER in density helps bass isolation, but worsens high frequency performance. This is totally counter-intuitive (at least to me), but is a good thing as far as cost and availablilty for music studios - it's why most home studios get best results using plain old fiberglass batt insulation inside walls, because that usually runs from about 0.5 PCF to around 1 PCF.

As to what you should add, 5/8 will work fine - if you can find/afford/handle thicker, going to 3/4 for one side would gain another 1-2 dB at the low end. Conversely, the RC does NOTHING at the bottom end, but improves overall STC by about 8 points, all of which is in the mid to high-mid frequency range.

CR glass - laminated if you can afford it, minimum thickness of EACH pane should be at least 1/3 the TOTAL sheet rock thickness for that particular side, more if you can afford it. Reason for this is that glass weighs roughly 3 times sheet rock, so that would maintain similar mass per leaf. In calculations, more is better (within reason) but using 3/8 and 1/2 laminated would match your walls (as planned) with essentially NO degradation, assuming 90mm distance between panes.

Splaying of glasses in CR's is argued back and forth - if you don't reduce the air space drastically, it won't hurt and probably helps. I would splay only the CR side, and do it narrower air gap at the top - this will cut down on light glare, as well as re-direct some early reflections to the ceiling, where you will (most likely) have an absorbent cloud to help control them.

Ceiling - if you use RC, again you'll need to start from the joists. This will also let you see if you have enough strength (span) for two layers - I'm running out of time, but I can calculate spans if you give me sizes of joists and center distances (and type of wood, if you have any idea) - generally, joists are sized so that you can add another layer without problems. I wouldn't spend the money on vinyl, sheetrock gives more bang for buck by far. Also, if that cavity isn't insulated you'll need to add batts. Ask for the heavier gauge RC for ceiling use - some of them are NOT rated for use in ceilings at all (Dietrich standard RC, for example)

Gotta go, let me know if (when) you have more questions... Steve

All these figures are calculations, and typically field measurements are worse by 3-5 dB due to other factors like sealing, weak links, flanking, etc -

Steve, thanks for the great answer. I am trying to finalize what I will be doing. Couple more questions to get even closer;

Walls- for my situation, although wanting, is to take off existing sheetrock, batt with regular old fiberglass insulation and put on regular old sheetrock. Question- 5/8" and 3/4" on one side and 5/8" on the other, or just single leaf on both walls one of 3/4" and one 5/8".

Ceiling- Do not want to tear existing down until ready for full studio contruction. What would be a good work around for the existing ceiling considering I do not want to tear existing ceiling down. Batting on top in attic? Plywood floor in attic (no existing floor now-single story house with attic)?

Windows- frame inside and glass 3/8" or 1/5" thick with acoustical sealant?

Doors- Solid core with weather stripping is what I am thinking. Big difference? Or not so much in my situation?

Thanks again for all the knowledge.

Keith

Walls - I meant double 5/8 on one side, then 5/8 and 3/4 on the other side - without the help of separate frames, wider air gap or RC, you need as much mass as you can get. As I mentioned, lower freq's won't notice the lack of RC but high mids (guitars, cymbals, part of the snare sound) WILL reflect the difference - IF you buy RC locally from a drywall supply, you should be able to get it for less than $.20 per foot, which would translate to about $17 for your dividing wall - however, your window, unless you can figure out a way to separate its frame into two isolated halves, will make it a dubious situation so I wouldn't bother in this case.

Ceiling - if you can work it so you get a total seal between plywood on top of the ceiing joists and the joists themselves, it would be worth it - insulation batts (the standard ones are fine for this) will help a few dB - an extra layer on the bottom (5/8 gypsum) would bring it up another 3-4 dB. Beyond that, you would be asking for trouble - typical ceiling joists are only rated for a 10 pound dead load (the weight per square foot of ALL construction, including the framing members themselves) each layer of wallboard or plywood adds roughly 2 pounds per square foot, and framing adds between 1/2 and 1 pound PSF. So, 3 total layers plus framing would average out to around 7 PSF, which is as close to design ratings as is sane. Before I would even suggest those changes I'd want to know more about what is already there, EXACTLY -

Windows - I'm assuming a typo, and you really meant 3/8 and 1/2 - if so, that's fine. The further you can separate the two leaves the better.

Doors - assuming the same quality of seals, you should see nearly 10 dB difference between hollow and solid core doors. Beyond that, seals will be the limiting factor until you get to a double door soundlock situation -

One other way that might be useful to you - if you take a standard hollow core, 1-3/8" thick door and add 1 1/2" MDF layer to each side, the result would be a mass/air/mass barrier that should be somewhere between 6 and 10 dB better than even a solid core, 1-3/4" door. IF you did this, you'd need good seals all around and heavier duty hinges or it wouldn't be worth it. However, that construction calculates at around 40 dB STC, with low freq performance essentially the same as the solid core. The improvement would come in at midrange and higher frequencies.

That's about it for now, gotta get some sack-time... Steve