Should I float these walls?

[aschatzb]

Hello Steve,

I'm posting an image of the wall in question, hopefully this will clear a few things up... My original image wasn't exactly clear on the shape of the wall.

I haven't been exactly psyched about starting this next project. Between the money and the time I won't be working on music in the studio, I'd much rather start this project in a year. However, I can't afford to keep upsetting the neighbor.

Do you think I might be able to create a temporary situation that might keep the neighbor happy for a year? The reason I ask, is you believe the weak link might in fact be the current "ceiling" or there lack of...

I've been offered brand new acoustic ceiling panels for free, enough to complete the live room. I'm not really into the entire acoustic ceiling panels aesthetic look, however, if this would buy me some time, I might drop the cash to get it installed and be done with it.... Do you have any suggestions? I'm sure you probably need a lot more info before you can make an educated guess.

thanks again,

andrew

[aschatzb]

here's the image of the wall...

[aschatzb]

Hello Again,

I just finished meeting with the local acoustic ceiling fellow. He doesn't seem to think the weak link is the roof (unfinished ceiling). He thinks the 12 inches of insulation in the truss should be absorbing plenty. Seemingly he has a lot of experience with sound transmission through ceilings and roofs. He's not exactly sure what approach I should take, but plans to sleep on it. One suggestion was hanging some baffles from the truss about a foot off the wall.

Anyway, I wasn't sure if this info might help in trying to solve this problem. Just though I should share...

thank you,

andrew

[sharward]

I just finished meeting with the local acoustic ceiling fellow. . . He thinks the 12 inches of insulation in the truss should be absorbing plenty.

What exactly is an "acoustic ceiling fellow"? Does he know the difference between "absorbtion" and "isolation?" Do you know the difference?

I really mean no offense. It's an honest question.

[Xalky]

I just finished meeting with the local acoustic ceiling fellow. . . He thinks the 12 inches of insulation in the truss should be absorbing plenty.

What exactly is an "acoustic ceiling fellow"? Does he know the difference between "absorbtion" and "isolation?" Do you know the difference?

I really mean no offense. It's an honest question.

I was thinking the same thing
You need mass to stop sound. Insulation has very little mass.

[aschatzb]

The Acoustic Ceiling fellow or guy (whatever you prefer), specializes in outfitting spaces with special acoustical needs. I did not ask him specifically if he understands the difference between isolation and absorbtion, but he better damn well know the difference if he's in this business and has been for many years. I imagine his diagnosis was from experience with dealing with similar situations.

Maybe his first guess is wrong. Perhaps he has no idea what he's talking about?

In anycase, I explained to him that I was trying to avoid building all my secondary walls for another year, if possible. He didn't have any instant answers, though he seemed somewhat convinced the ceiling was not the weakest link... He wasn't even sure if the secondary walls could be avoided.

It seems to me, that I'm on the track to start construction of the secondary walls and ceiling in order to obtain the level of isolation I need from the neighbor. However, in the meantime, I'm just researching other options before I set off on this 4 month 15,000 - 20,000$ project...

anyone???

thanks,

andrew

[knightfly]

Andrew, it sounds to me like your "acoustic ceilng" guy has no clue about the physics of actually STOPPING sound; first, no amount of absorption in the room will make enough difference to hear with the naked ear - the ONLY thing that counts here is WELL-SEALED MASS. One is good, Two is best, 3 (or more) will usually CAUSE more problems than they FIX. You start getting into multiple resonant conditions that, especially at LOW (spelled D-R-U-M) frequencies, will seriously WEAKEN the isolation.

The reason I'm wondering about the roof/ceiling, is that it appears as if your outer roof sheath and rain covering (shingles, whatever) are, other than insulation, all that's between you and the neighbor; that, and he is up the hill so more inline with the roof surface than wall surfaces, so there's more likelihood of a direct path for any sound leakage out the roof.

You can pretty much analyze this for yourself if you just say to yourself, "MASS, AIR, MASS" - anything LESS or MORE is WRONG.

So if you look at your outer sheath, it needs to be one continuous, SEALED, HEAVY leaf of mass which can consist of any number of LAYERS, as long as the layers are NOT separated by even a fraction of an inch of air space - a good saying for both this and your INNER mass leaf is, "if it don't float, it won't stop sound" -

Second, the air space - anything that BREATHES is considered "air" for purposes of this definition. This includes rockwool, mineral wool, blown in cellulose, rigid or fluffy fiberglass, sheep wool, etc - it does NOT include ANY of the normal FOAM building insulations; these are virtually ALL CLOSED CELL, therefore do NOT breathe, therefore won't absorb and dampen the interior space between masses.

Third, you need an INNER leaf of mass; this also needs to be continuous; including the ceiling and any cracks. Sealed. Again, think like a boat builder.

Adding this second mass "cheats" the law of physics that states that the best you can get for a given increase in mass is 6 dB for every DOUBLING of mass - the air gap causes the overall resonance of the barrier to lower dramatically, and you want this resonance to be as low as you can get it.

I've gotta go to work right now, I'll put up an example of this concept tomorrow if I get a chance... Steve

[aschatzb]

Hey Steve,

I'm with you... I believe you're right about the ceiling. It just makes sense. Perhaps I misunderstood what the "ceiling guy" was saying. The bottom line was, he didn't believe installing an acoustic ceiling was going to solve this problem...

It doesn't seem like properly installing 2 layers of gyps directly on the truss is going to solve this problem either. Or will it? I'm still hoping someone is going to tell me I don't have to build those walls to solve this problem...

Anyone?

thanks:)

andrew

[knightfly]

Wish I could, Andrew, but physics don't agree. Only two ways I know to fix sound leakage is either LOTS of mass, or TWO masses separated by an insulated air gap and DAMPED as necessary to minimise or eliminate any ringing of either mass.

There are MORE expensive ways, the Brits have covered this at BBC with their "triple Camden" walls (3 heavy double-leafed walls, total thickness of everything around 3 FEET)

Main thing for you is to ensure that your OUTER mass leaf is contiguous; that's not likely unless the place was designed from the ground up to be soundproof. Pretend you are a sound; then, look for weak spots (little or no mass, cracks) to get through; if you find them, the outer leaf isn't ready.

Even if the outer leaf IS totally intact EVERYWHERE, unless it weighs about 150 pounds per square foot of surface you will STILL need a second INNER leaf of mass and some air gap to stop drums.

Believe me, If I'd found that "magic bullet" of cheap/easy soundproofing, I'd be typing this from my private island in the Mediterranean, or more likely having my lovely assistant do it while I was getting my morning massage... Steve

[aschatzb]

Yo Steve,

That's hilarious! I thought you already were on a private Island in the sun? Hmmm, wait a second, that's really just a metaphor...

Anyway, thanks again for being here and delivering me the news! I wish I could have just thrown up a few layers of 5/8 gyps right onto the truss and been done with it... Unfortunately, the only magic bullet I got is the one in my foot. I was so psyched to start work, I even had a few really great sessions until Mr. Neighbor showed up. I guess I better put away my mics and break out the table saw. Sweet!

take care, I'm sure I'll be in touch as soon as I hit my first snag.

all the best,

andrew

[sharward]

I thought you already were on a private Island in the sun?

Now stop that -- we all know that Oregon doesn't have a sun!

Always a good idea to know (1) what sound levels you'll be reaching in your space and (2) what the specifics of your local noise ordinances (if any) are, so that you can (3) subtract the two sets of numbers to know what level of isolation you're going to need.

--Keith

[knightfly]

"we all know that Oregon doesn't have a sun"

Sure we do; it's gray, varies in size and number, and travels across the sky in whatever direction (and speed) the wind is blowing. It brings us moisture to sustain our addiction to mud, it keeps us from having to mow the lawn when our wives get snippy about it, and twice a year it goes away long enough for us to see this strange, featureless blue thing for a few minutes...

So WTF you mean we doesn't have a sun? I just squeegied some of it off the front porch, so I know better...

[sharward]

Let the record show that I personally actually love Oregon weather (and I'm not foolin')!

[aschatzb]

Hey Guys,

In ashevilleland, there is no "ordinance" exactly... It's "whatever is reasonable," which is completely subjective. My neighbor complained to me on a sunday afternoon session. Obviously, he doesn't think it's reasonable.

So, what it comes down to, I just have to make this guy happy. Which means building all those secondary walls...

later:)

andrew

[sharward]

In ashevilleland, there is no "ordinance" exactly... It's "whatever is reasonable," which is completely subjective.

That's really unfortunate. Subjective standards are difficult to engineer because the target is constantly moving.

Are you certain that is the case, or are you relying on what "someone" told you? (Even if that "someone" was a police officer, with all due respect to police officers, they don't know all of the laws they should be enforcing, or conveniently "forget" about other aspects of the law. )

For example, in my city, there is a subjective standard that uses the "touchy-feely" language barring "unnecessary" noise as defined by "persons of reasonable sensitiveness," but there is also an objective standard that specifies what decibel levels can be exceeded at various points in the day and for various durations per hour. I need to be in compliance with both standards, but I believe if I'm in compliance with the objective standard, I'm in a better position to defend myself if/when accused of being in violation of the subjective standard.

Bottom line, be certain what laws may exist in your community, as the costs of being out of compliance can be severe.

. . . I mention from time to time that communication (and a mild amount of ass-kissing) goes a long way toward peaceful coexistence - if you start out making noise, and try to stick to the "rules" of acceptable levels, someone like this neighbor will ALWAYS bitch, even if you're BETTER than the so-called rules require in your area.

If you start by having a talk with the neighbor(s), and explain that you do NOT want to cause them any problems, and follow it up with some "dime store science" display, like having someone play full frequency music inside your area as loud as you'd ever do, standing WITH the neighbor in THEIR space with a sound level meter and, while communicating with your helper, have them turn DOWN the music til the neighbor is happy, then measure inside the room and note the DIFFERENCE between the two levels, that will give you a good idea of how much MORE sound isolation you need.

This also gives the neighbor less reason to bitch, because you're obviously trying to be the good guy - it's a lot like the ploy of inviting the neighbors to your party so they'll be less likely to call the cops, even if they DON'T attend... (Source)