MLV or NOT

[blackbox]

just wondering about the use of Mass loaded vinyl.
we are planning of layering our walls like this
soundboard- 5/8" sheetrock- MLV _1/2"sheetrock.
now how worth it is it to use the MLV in this setting.
or should i replace something with it. we are doing this on all our walls throughout the live room. and in our amp booth.
anyone?

[sharward]

. . . if you do a search on "vinyl", or MLV, it should become obvious what most people's opinion of this is - there are places where the expense might justify it, but they are few. It's nearly impossible to beat plain old gypsum wallboard - my local (west coast) cost runs around $6.70 a sheet recently for 5/8 4x8 panels, compare that to MDF, OSB, plywood, "sound board", and there is NO CONTEST. Mass is mass, and mass kicks ass. (source)

So, in a nutshell, "NOT."

By the way, blackbox, you're jumping the gun a bit. Please read and follow all of the directions on the "Before You Post" announcement.

[blackbox]

cool,
so would you say that i will have better results if i use an extra layer of 5/8" gypsum than putting in a layer of MLV despite the cost?
how does this wall sound to you? 5/8" gypsum - 1/2" gypsum -
"soundboard" - 5/8" gypsum or 1/2" for final layer.
do you recommend putting any sort of material between the layers of gypsum.
one more thing-
the "sheetrock" at my local hardware store (san diego) is like $9.50 for a 4x8 sheet of 5/8". any tips on where to find a better deal?
sorry about the redundancy of my questions!
i will search more before asking next time!

[knightfly]

blackbox, first off welcome;

second, please follow the "before you post" link which will answer nearly everything you've asked so far;

third, is that price at something like a Home Depot ? Last week my local (Oregon) HD had 5/8 4x8 rock at $8.70, so the price has gone up again. Might try local drywall suppliers if they will talk to a non-contractor - yellow pages/phone is still hard to beat for local availability... Steve

fourth; forget sound board; bad name for a waste of time and money. replace with another layer of wallboard.

[blackbox]

thanks!
is it worth it to go 4 layers of sheet rock?
the only reason i was thinking sound board was because it seems to have sound"deadening" propeties.
if i do use 4 layesr of wall board should i go 5/8"-1/2"-5/8"-1/2"?
or should i sandwich the 1/2" between the 5/8"?
you guys have save me so much grief and money and for this......
I THANK YOU!

[sharward]

is it worth it to go 4 layers of sheet rock?

I'm going to do no fewer than 3 layers on my project... I may end up doing 4 or 5 -- I hope to have that "nailed down" (figuratively) this week.

the only reason i was thinking sound board was because it seems to have sound"deadening" propeties.

It's probably a moot point (so you don't have to answer this if "sound board" is now off the table)... Define "deadening." There's "dampening" (which is, as I understand it, like putting your hand on something that's vibrating in order to silence the resonance of it), and there's "isolating" (which is putting a loud thing in a thick box so that it can't be heard, or can be heard much less, outside of the box). I could be wrong (I'm an amateur here too), but I see/hear the word "deadening" a lot and I'm not its meaning is universal... It may be a "meaningless" word.

if i do use 4 layesr of wall board should i go 5/8"-1/2"-5/8"-1/2"?
or should i sandwich the 1/2" between the 5/8"?

There are some benefits to using multiple different thicknesses of wall board. However, those benefits are trumped by the advantage of using all layers of the same as thick as you can go thickness. Multiple thickesses is good, but lots of thickness (even if all the same) is better, in terms of isolating low end, bassy sounds. Plus, it's a pain-in-the-butt to work from two or three stacks of wall board and keeping the scraps sorted.

you guys have save me so much grief and money and for this......
I THANK YOU!

You're welcome. Now show your appreciation by following the "Before You Post" announcement! (Dude... We're running out of ways to politely tell you that!)

[ONEoverZERO]

So my studio construction in Vermont (in the country) is experiencing more bleed through the building walls than is acceptable (even though the closest neighbor is 200+ feet away...it is pretty loud outside). Original construction of walls is 1/2 sheetrock and some fiberglass bat insulation. Not much between the noise and outside.

Since I only need to cut the bleed to an acceptable level, I was thinking of just hanging either 1LB or 2LB MLV sheets either on the interior walls or the exterior walls of the building. Questions related to this:

1) The website on STC rating suggests that a change +/- 10 STC = roughly twice (or half) as loud. The 1B MLV is 26 STC and 2LB STC is 33. Based on this I could expect a very significant reduction in bleed (in dB)? Agree / Disagree? Seems a normal wall with 5/8" sheetrock on both sides (unstaggered) is only mid to high 30s STC, so this layer of MLV can approach the the effectiveness of a crude wall. If I was starting over I'd just use the best possible sheetrock, staggered metal studs, and bat insulation and be done with it ...but given where I am now I think that it is much easier and cheaper (figuring in labor costs) to just add this MLV layer.

2) If I put this stuff on my interior walls (actually hanging in front of walls), am I then significantly changing the sound characteristics of the room? Would the exterior of the building be better?

Thoughts? Thanks!

[ONEoverZERO]

So my studio construction in Vermont (in the country) is experiencing more bleed through the building walls than is acceptable (even though the closest neighbor is 200+ feet away...it is pretty loud outside). Original construction of walls is 1/2 sheetrock and some fiberglass bat insulation. Not much between the noise and outside.

Since I only need to cut the bleed to an acceptable level, I was thinking of just hanging either 1LB or 2LB MLV sheets either on the interior walls or the exterior walls of the building. Questions related to this:

1) The website on STC rating suggests that a change +/- 10 STC = roughly twice (or half) as loud. The 1B MLV is 26 STC and 2LB STC is 33. Based on this I could expect a very significant reduction in bleed (in dB)? Agree / Disagree? Seems a normal wall with 5/8" sheetrock on both sides (unstaggered) is only mid to high 30s STC, so this layer of MLV can approach the the effectiveness of a crude wall. If I was starting over I'd just use the best possible sheetrock, staggered metal studs, and bat insulation and be done with it ...but given where I am now I think that it is much easier and cheaper (figuring in labor costs) to just add this MLV layer.

2) If I put this stuff on my interior walls (actually hanging in front of walls), am I then significantly changing the sound characteristics of the room? Would the exterior of the building be better?

Thoughts? Thanks!

[Soundman2020]

ONEoverZERO, you seem to be having the same Forum Rules problem as the original poster! Please read the forum rules for posting (click here).

Anyway, about your actual questions:

The website on STC rating suggests that a change +/- 10 STC = roughly twice (or half) as loud.

Which website on STC ratings? There are many... and most of them forget to tell you that STC is a useless rating system for STUDIO walls, since it does not take into account the bottom 2-1/2 octaves on the musical scale, and neither does it take into account the top 2-1/2 octaves on the musical scale. It's fine for rating walls that are supposed to reduce the level of voices, office noise, school noise, etc., which is all in the mid range, but worthless for judging the ability of a wall to reduce the level of full-spectrum music, extending right down to deep bass frequencies.

Also, it is very wrong to say that a "a change +/- 10 STC = roughly twice (or half) as loud". It is correct to say that a change +/- 10 decibels is perceived by most people as being roughly twice (or half) as loud. That's a very, very different thing. There is no direct relationship between STC rating and decibels. Yes, STC numbers start out based on decibel measurements, but that relationship goes out the window due to the way the ratings are actually calculated by the curve-fitting algorithm and the allowed defects. In reality, there is no longer any direct relationship between STC ratings and the ability of a wall to reduce sound levels. Do not get caught in the error if trying to use STC to build a good isolation wall for your studio.

The 1B MLV is 26 STC and 2LB STC is 33

Not true. That flies in the face of the laws of physics. There's a basic law of acoustics (= physics), called "mass law", which goes like this:

TL(dB)= 20log(W) + 20log(f) -47.2

That tells you exactly how man decibels of Transmission Loss ("TL") you get for any type of wall leaf, at the frequency of "f" Hz, where the wall panel weighs "W" pounds per square foot.

There's a more compact "empirical" version that gives you the overall TL for the panel, across all frequencies, that goes like this:

TL(dB)= 14.5log(W) + 23

Plug in the surface density of that MLV, and you get this:

For 1 pound MLV: TL(dB)= 14.5log(1) + 23 = 23 dB (not 26, as claimed)
For 2 pound MLV: TL(dB)= 14.5log(2) + 23 = 27.3 dB (not 33, as claimed)

So the claims are wrong, plain and simple. There are no magical materials that somehow beat the laws of physics.

Based on this I could expect a very significant reduction in bleed (in dB)? Agree / Disagree?

Disagree, strongly. Another way of looking at "Mass Law" is that it implies that every time you double the mass of a wall leaf, you get an increase of 6 dB. In reality, it is more like 4 to 5 dB, as measured empirically. So, assuming that your current leaf has 1/2" drywall, and you add a layer of MLV on top of that, what you would get is this:

For 1/2" drywall alone: TL(dB)= 14.5log(1.7) + 23 = 26.3 dB (1/2" drywall weighs about 1.7 psf)
1/2" drywall plus 1 lb MLV: TL(dB)= 14.5log(2.7) + 23 = 29.2 dB

So you'd get an increase of about 3 dB in isolation. Subjectively, you'd hardly notice the difference at all.

And if you used the heavier MLV:
1/2" drywall plus 2 lb MLV: TL(dB)= 14.5log(3.7) + 23 = 31.2 dB

That would be an increase of about 5 dB: Noticeable, but nothing to write home about, and certainly not worth spending thousands of dollars on.

Seems a normal wall with 5/8" sheetrock on both sides (unstaggered) is only mid to high 30s STC

About mid 30's DECIBELS. Which is about one hundred times less isolation than what you need for a typical studio...

but given where I am now I think that it is much easier and cheaper (figuring in labor costs) to just add this MLV layer.

I seriously doubt it would be cheaper! Take a look at the price per square foot for 2lb MLV, then multiply by the number of square feet of wall and ceiling that you need to cover...

Amazon has it at about US$ 170 for a 4' x 10' piece:
http://www.amazon.com/Loaded-Vinyl-Squa ... B007N348OG

... which is enough to cover a single sheet of drywall. Figure a typical double garage measures about 20' by 24', so you'd about 20 sheets for the walls, plus another 10 or so for the ceiling. 30 sheets x US$ 170 each = US$ 5,100. I would not call that cheap at all!

And you'd be investing all of that to gain about 5 dB of isolation, with luck... Doesn't sound like a good deal to me. (Even if you could find lousy quality MLV for half that price, it would still be a damn expensive way of getting more mass.)

If I put this stuff on my interior walls (actually hanging in front of walls), am I then significantly changing the sound characteristics of the room?

Nope. Assuming you just staple it to the existing wall, it would not be acting as a limp membrane, so not much change to the room acoustics.

Thoughts?

Mass law is not your friend. MLV even less so. The ONLY way to get good isolation at a reasonable cost, is to do a proper fully-decoupled 2-leaf MSM system, in one of its many forms. Mass Law is single leaf, and is not feasible for high isolation. Multiple leaves (more than 2) creates issues with low frequency isolation, not to mention cost, complexity, and the space it needs.

There's a reason that pretty much all professional studios use 2-leaf systems: It's the most cost-effective way of doing it. If there was a cheaper way, they would do that instead! You can bet your bottom dollar on that.


- Stuart -




- Stuart -