John Sayers' Recording Studio Design Forum Archive

and somebody will invariably say RTFM, but this is my first post, so give me a break. I'm building a live room for a 5 piece band next to an obnoxious and belligerent neighbor. He has 911 on his speed dial and won't even tolerate my compressor.

Live room-18x15.

Walls - 1 inch fresh stucco over 5/8 ACX on 2x4 studs. Insulated with 2 layers of 2 inch Dow R20 stiff board cyanoacrylic insulation. Inner wall sheathed with 5/8's again, I'm planning on adding 2 layers of 5/8's drywall.

Floor- concrete. Haven't done it yet.

Is this wall arrangement gonna keep him off my butt, and what should I do with this floor to attenuate low frequencies?

Thanks in advance...

I doubt it - first, people like that THRIVE on finding things to complain about - second, the insulation in your walls is doing NOTHING for sound because it's closed cell if Im not mistaken - quiet batt spun fiberglass would improve things by about 6-8 dB in a resiliently coupled wall, and probably 3-4 dB in a solid coupled wall like yours.

There are a couple (or more) problems with what you're planning - one is, since your studs are contacting both inner and outer wall sheaths, there is no isolation between them and sound will penetrate much easier - the only way around this is to remove the inner paneling, then either put Resilient Channel on the studs and 3 layers of drywall, or move in about 2-3", build a second frame, and triple drywall THAT frame on one side only.

Another problem - odds are, even if you fix the wall you'll get flanking noise (called an "end run" in football) through the ceiling/attic/roof, since these are most likely no more hermetically built than any other "normal" walls.

At the risk of sounding like I'm saying "RTFM", (I am) there is a lot more discussion on these problems in the "sticky's" section, especially the ones named "complete section", and the one on floating floors -

Do you have any actual sound level measurements/distances to evil neighbor/ordinance quotes? There are times when it's a LOT of fun to shove this stuff up the guy's backside by finding out that you're NOT in violation of any ordinances (10 pm is the typical cutoff time, and if you can measure the neighbot's lawn mower noise and prove you're no louder...

Anyway, try those sticky's, give it a bit of thought and let's discuss it further - sooner or later, we can usually find a plan for almost anything... Steve

Thanks for the reply. I've been spot reading today while keeping my hands on the job and have learned a few things.

On removing the inner 5/8's, it's glued screwed and hermetically sealed and identical to the angled ceilings' construct, so it's not likely that I'll be ripping anything out. Yes, I know I've essentially built an ice chest.

My drywall guy is coming with a plan for two layers of 5/8's with channel on the ceiling and I'm thinking a bit of air gap is going to help a bit on the spl's if I alternate the screw pattern to avoid the studs and leave at least SOME air in there. Right? And I see the drywall shouldn't touch the floor.

I've seen some fairly expensive 1 1/8" foam core treatments from acousticsolutions.com that may become a last minute cure, but as you stated, a neighbor like that is going to always find something to complain about.
He doesn't like my bike collection either. (HD)

Having done some homework around here today I think my floating deck plan will work out as well as can be expected. I consulted with a few other people knowledgeable on the subject and they've indicated that the cheap soft neoprene hockey pucks from 49cent-puck.com will do a fine job of isolating my framing from the floor if I set them at 24 inch centers. Is that within functional parameters? There won't be any significant weight issues.

I've double walled my 18 foot wall between the live room and the control room with a two inch gap, again with the stiff insulation, 5/8" ply and 2 layers of 5/8's drywall. The existing wall was an exterior garage wall that has R-30 and 5/8's drywall and will get the 5/8 ply, double drywall treatment too. The thickness of the combined walls will be about 22 inches.

I'm hoping this will work well keeping this penis noggin out of my hair, and I tend to think it may, since I can't hear a chainsaw in his backyard with all the doors closed.

I should add that there are no windows in either room. I added a backdoor on the live room that is 2 solid core 1 1/8" doors with a 1 inch carpet pad sandwich and another 1 1/8" slab of ply on the exterior with 6 right angles padded with door sealer for the sound to get around. It doesn't.

Whew.

So, what else do you think I might do to further insulate this space from this terrorist neighbor? Besides arson, homicide and other assorted daydreams I relish, of course.

Additional notes:

This space is well off the street. Cops driving by in response to his calls usually don't hear a thing.

His bedroom window is 3 feet from the front of my building, but not concrete-coupled by about 6 inches. I'm contemplating a foot deep trench full of sand. So far, a great place for my air compressor and table saw.

Would sand under my raised floor work better than other insulators?

The live room is a new addition from scratch.

Lot of questions, I know, sorry.

Thanks for your response. I can tell you are a respected voice in here.

the Old Guy

,edit> I know, I'll draw it up and post it in the next day or so.

"Besides arson, homicide and other assorted daydreams I relish, of course. " - A man after my own heart; unfortunately, this "politically correct" crap keeps us from "firing a warning shot to the head", tempting as it may be...

Looking forward to your drawings... Steve

Ok, sketchy at best, but done in Paint:

And finally...

I should add that the live room add-on was originally meant to be a tool shop. I changed plans mid-framing to making it a live room and now will be cramming all my tools (a lot of tools) into the front half of the control room bldg. which now has new 8" thick insulated doors that will get sealed.

That bldg was originally a garage. It was insulated and drywalled when we first moved in since I kinda live in the garage anyway.

The 24x24 bldg was added to house tools, bikes etc and has become a party barn, to say the least. Currently it's un-insulated.

The drawing doesn't show it, but wall B is shimmed an inch to the center to avoid the parallel with the back wall.

I know I'm going to have some reflection work to deal with in both rooms, but my primary focus right now is sound containment.

Thanks again

I suppose I don't need to add that wall B is also full of wiring for everything...

I'm hoping you're still reading in your spare time, because there are quite a few things you're planning on doing that won't be worth the time, much less the material cost - besides the "sticky's", here is a thread with a good comparative diagram on TESTED wall assemblies (it's about halfway down the page) -

http://www.johnlsayers.com/phpBB2/viewt ... =9704#9704

Note the positioning of mass vs air/insulation space in each example - in particular, note that the EXACT same amount of material is used for the 40 dB wall as is used for the 63 dB wall - the only difference is how many leaves (centers of mass) and air gaps. Also note that in several cases, you can improve performance by REMOVING material.

This is the best way I know how to explain the "2-leaf" concept - If I had a buck for every "experienced carpenter/drywaller" who's told me "Resilient Channel doesn't work", I could (at least) buy a really nice steak and lobster meal for my (extremely patient) wife and me - and every time I've been told this (except one, who was even LESS clued in) - "I put RC on the existing wall and added a couple layers more drywall, and it didn't get any quieter - if anything, it was worse..." - the above link should go a long way to explain this - basically, air is a "spring" - the shorter the air path, the stiffer the spring; the stiffer the spring, the more coupled the wall surfaces, and the more crap gets through.

BTW, the one guy above that was different? He had just nailed through the RC and drywall directly into the studs - musta thought he'd forgotten the "quiet spell" he was supposed to cast to make this "magic" work right...

As far as your staggered stud wall, if you want isolation why not use separate frames entirely? Using your proposed/existing construction (adding 2 layers 5/8 wallboard to the stucco/ply/frame/ply), single stud frame gives (approximate) STC 45 - staggered stud or RC gives STC 54, and fully separate frames (double stud) gives STC 71 - these are all with 4" air gap and standard fiberglass insulation. Your closed cell foam is not helping at all, so your actual STC will be around 5-6 dB less. The addition of 2 layers of 5/8 wallboard directly on your existing wall will only help by about 3 dB, since the more mass you add the less effect each layer has.

In the above STC approximations, ALL except the true double frame only give about 25 dB loss at 50 hZ (the lowest my calculations can do) - the double frame, (which would require removal of the inside layer) raises the isolation to 30 dB at 50 hZ and an overall STC of 71.

Another problem - your isolation is only going to be as good as its weakest link - it's possible that your lounge area could leak enough sound through that sliding door and outside to negate what you do in the "nasty neighbor" wall, as could your ceiling/roof construction - do a search (in this forum) on "flanking", there are a couple of links to some Canadian papers on flanking noise that explain this.

I'm not trying to discourage you (no, really ) but if you don't want to throw good money/time after bad, you need to understand the physics of sound isolation before you do anything else - your problem CAN be solved, but in the long run you will probably be better off UN-building a thing or two before you continue - your inner plywood, for example - if it won't come off easily, you could maybe cut along the edges of the studs with a skil saw/rotozip combo (depth control) and leave the strips over the studs, opening those cavities so you can ditch that useless foam insulation and get your mass layers where they belong - you will get a HUGE return in isolation for this, but again remember the "weakest link" thing -

I hope I've given you a few things to think about; I know you're resisting any removal of already-built stuff, and I feel your pain - one of the most depressing parts of what I do here is having to tell people this, but there is no practical way to get around the physics, and intuition is no substitute for knowledge when it comes to sound isolation... Steve

Thanks, Steve.

I'll reread your post a few times till it sinks in.

A thought I had over the last few days was covering the inner layer of ply with an absorbtive material and adding two new walls angled into the SW corner (per the drawing) with a better insulation (rockwool) and then adding the two layers of drywall over that. I don't know what the exact angle is, but it seems like that may increase my STC, particularly if I rest these walls on the floating deck. ?

I have to hesitate on deconstructing anything due to the incredible amounts of Liquid nails present in the wall. It would take a bulldozer, so I have to work with what I've already done. It would actually be cheaper to build a cinderblock wall on the exterior and fill it with sand.

I'm still reading...

OK, here's what I'm thinking on your "shitty neighbor wall - if you have closed cel foam insulation in that wall, it would tend to act more like a third leaf (sometimes a bit better for midrange but WORSE for low frequency) - next, having the inner leaf firmly mounted to the studs makes that wall a resonant chamber at approximately 76 hZ, which will pass a goodly amount of bass guitar and drums with little attenuation. That wall, calculated with standard fiberglass batts, would have an STC rating of around 42 dB - using the foam insulation, the STC would likely drop by 3-4 dB, and the low frequency isolation would be even worse than calculations, probably around 18-20 dB. You would need probably twice that amount of isolation to keep the "NFH" from hitting the speed dial -

I know materials aren't cheap, and are getting less so every day, but I seriously doubt that you'll get the isolation you need without tearing some stuff out - specifically, setting a circular saw to 5/8" depth and ripping parallel to your studs, leaving the 5/8 ply strips over the inside edges of your studs but removing the rest of the plywood and that poly-crap insulation - Then, you could either just add RC and 3 layers of drywall (better mass and much cheaper than plywood) or you could build inner frames and do a true double-framed wall system - the further apart these two leaves are, the better LF performance the wall will give, all other things being equal.

The approximate difference between what you have now, and what you'd get by ripping out the inner ply/bad insulation and using the right insulation with double frame, 8" air gap and 3 layers of 5/8 wallboard - 20 dB vs 35 dB @ 50 hZ, and STC 73 vs. STC 40 for overall wall performance. Pretty large difference -

One thing I've not seen mentioned is your ceiling construction or roof - this concept of two leaves, one air space will need to extend to every barrier between you and the world in order to get really effective isolation - standard ceilng /roof construction SUCKS for this, because typically roofs are vented to prevent rot/condensation, and so the only sound barrier is the ceiling material; typically, a single layer of paneling of some sort. Pretty crappy. Usually, if the joists will take it a dropped ceiling on resilient mounting is the way to go, if you first double the ceiling layer then new secondary joists and another double layer (insulation between) this gives you your mass-air-mass envelope, and because the roof is vented you just ignore it as far as sound isolation is concerned.

It's much easier for me to advise BEFORE extra construction has been done; it's always hard to recommend undoing hard work, but it's harder to achieve any noticeable degree of soundproofing unless the basic principles are followed, and it's actually cheaper and more effective to "back up and start over" than to throw good money after bad... Steve

Are the walls on this picture measured?
What is the link to the original site it came from?
Isn't a reference to the source/page a good idea?

Eric

I should do a little more clarification on the actual wall constuction as it exists.

1" stucco
2 layers 60 lb. felt
5/8" ACX
2x4 studs (actually 3 1/2")
4 actual inches of the poly foam, glued in with LN.
5/8" ply again.

That last layer of ply has a 1/2" gap to the studs, 3" screws, and the back of it has LNails all over it, top to bottom, side to side. This wall isn't going anywhere soon, but thanks for the suggestion. The room is an ersatz earthquake shelter and it would take a chain saw to dig it all out.

The ceiling is built the same way in the live room, and it isn't vented.

The control room has 6" R30 stuffed up in it, but I haven't covered it with anything yet.


After reading around here, I reiterate my recent idea: adding RC to the inner plwood horizontially, staying off the studs and adding 3/4" SA panels over that, leaving an air gap of about 1 inch.

Then building an inner wall with 24" centers, packed with wool and 2 layers of 5/8's drywall, with a 4 inch gap to the outter wall, and building it on top of the floating floor.

I'm fairly clear about the floor. In addition to the various layers, I have to compensate for a slope that goes from 4" to 8" North to South.

The ceiling should get RC and 2 layers of 5/8's, as I am understanding it now?

I'm curious about an accurate way to measure the STC of what's already there. I do have a tone generator, a dB meter and a freq analyser with pink noise I could run through the spkrs that will be in there when it's all done. Would that be accurate enough for measuring STC's?

Eric, I think you're already looking at the source - those files are uploaded to this site -

OG, you're reaching into territory where Eric's much deeper knowledge of material behavior will be very valuable - Now that I fully understand what's been done to your walls and ceiling, it would seem to me (Eric, feel free to jump in here and add whatever you feel will help or correct) that what you have is in fact a single leaf, made up of various materials/densities/propagation speeds, etc - Eric, being a degreed acoustician and excel whiz, might be able (with enough time, LOL) to help you calculate the TL of those walls, but I have not had enough time to dig into most of the resources Eric has kindly provided and expand my consciousness enough to "wrap my head around" most of it (I have, however, bookmarked or downloaded everything, thanks again Eric)

Anyway, to my mind what you have is a single leaf wall, made up of 1" stucco (concrete, or close),5/8" plywood, 4" closed cell foam, slightly visco-elastic layer of construction adhesive, and another layer of 5/8" plywood - in all this, there is no effective air gap but just different density mass layers with different coincidence dips - Again, I'm on "thin ice" here, if Eric differs with me we BOTH should listen -

If my understanding is correct, then (also considering the difficulty of removing any of this) your least offensive and most effective option would be a separate frame (filled with fiberglass batts, NOT foam) and 3 layers of 5/8" gypsum wallboard, all done according to the techniques in the "complete section" sticky and the USG manual, with no Resilient Channel, no "special soundboard", just good hermetic construction using REAL acoustic rated caulk around edges and each layer properly mudded and taped (but not worrying about smooth enough to paint) -

If you do these inner walls on a floated floor, that part of the construction shoud work well for you - the ceiling, considering it isn't flat, would be more of a problem to achieve a separate frame for - somehow, you will need an air gap of several inches and an inner mass leaf similar to what I described for your walls - if your ceiling joists/rafters can take the weight, maybe some steel channel suspended from commercial isolators such as Kineticsnoise.com makes, and hang your multilayers of gypsum on those steel channels. I've not done this myself, maybe Rod Gervais would have some ideas on how to isolate a "mansard style" ceiling's inner leaf.

Let's see if either Eric or Rod thinks I'm anywhere close to reality here... Steve

Oh, almost missed this - you can't measure STC, only calculate it after taking measurements at frequencies between 125 hZ and 4000 hZ - and even if you could, for music it is not adequate. Ideally, what you want is a good STC wall that also has improved low frequency TL - the two are not the same.

Basically, STC is a weighted calculation, strongly referenced to Transmission Loss (TL) at 500 hZ and originally designed as a measure of human speech isolation, nothing more - there is a half-hearted attempt at replacing STC with MTC, which stands for both Machinery Transmission Class and/or Music Transmission Class, which does take into account frequencies lower than 125 hZ - unfortunately, MTC doesn't seem to be gaining much use from what I've seen so far.

TL, on the other hand, is measured at each frequency band individually and is more indicative of how much music will escape a barrier - if the TL at lower frequencies isn't good enough, all the "thump" from drums and bass will penetrate (and annoy your "NFH" - Neighbor From Hell) -

TL at higher frequencies isn't all that hard to accomplish - it's the lower ones that get tough. The ONLY things that work at lower frequencies are lots of mass, two leaves of that mass (not three, or four, etc) no hard coupling between those leaves, and air space(with OPEN cell insulation like fiberglass or mineral wool in it), and good damping of the leaves - the more mass, the better - the wider air gap, the better - if the insulation batts press into the gypsum wall panels they help damp the panels, which cuts down on panel vibration (good thing) - Beyond that, the lower the frequency the more important a PERMANENT hermetic seal becomes, which is why I never recommend anything but ACOUSTIC rated caulk, because in a few years (or less) anything else will develop small cracks which start eroding your isolation at lowest frequencies first.

If what you're calling a dB meter is a Sound Level Meter, depending on which one you have it may help some - the Radio Shack ones, although arguably the best bargain going, do NOT go down to low enough SPL ranges to help a lot with isolation issues, but WILL help you make sure you're within noise limits for most sound laws -

If you can get a time when your neighbor isn't home, that would be the best time to perform a test - I'd crank your sound system up to as loud as you'll expect to ever be, then go to the property line and measure the levels - most ordinances use "A" weighting for this, so that's what I'd use - the difference between dB levels in your room and dB levels at the property line are not an exact measure of your wall's isolation, but will indicate approximately how much MORE isolation you need -

Another way is to turn your system up til it's as loud as you'll use, check the SPL in the room, then (cell phones help with this) have a wife/friend/band member start turning it down while you're at the property line, until you just can't hear it - now, re-measure the level IN the room, subtract the two measurements, and that's approximately how much improvement you'll need in your walls/ceilings, etc -

Gotta run for now, but I think we're making some progress here - hopefully Rod and Eric both will add their comments and insights... Steve

Steve,

Thank you so much for this insight. I really appreciate it!

Your thoughts speak most directly to me.

By some great movement of Karma, my neighbor has just put his house up for sale. My paradigm has shifted. I'll start a new thread.

My 24'x24' is now going to be my live room, and my previous control room will move into the previously dedicated live room.

At this point, today, I'm collecting champagne corks, but tomorrow, a new plan begins.