Author Topic: How much does STC go up with Mass-Loaded Vinyl?  (Read 5054 times)

Stephanie

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How much does STC go up with Mass-Loaded Vinyl?
« on: March 12, 2003, 12:29:55 AM »
I'm thinking of installing a couple of layers of Mass-Loaded Vinyl under my carpeting. What kind of effect on the STC will those layers have? Say the STC of my floor/carpeting is at 38 now. If the MLV has an STC of 21 - and I apply two layers - how much will the STC go up?
Also, what kind of effect will the MLV have on impact vs. airborne noise? Is the MLV more effective with impact or airborne?



John Tower

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Re: How much does STC go up with Mass-Loaded Vinyl?
« Reply #1 on: March 15, 2003, 08:19:30 AM »
Stephanie,
 Unfortunately, the answer to your question is, it depends. There are multiple factors at work that are likely allowing sound to come through your floor.
The STC of MLV is 26 by itself, but that does not mean that adding this to your floor will simply add another 26 STC to your floor. Something called Mass Law comes into play that states that you get a 6DB increase in STC for every doubling of Mass. What is hard to say is just how much more mass you are adding to your floor with 2 layers of MLV vs. what is already there with plywood etc.. With two layers of MLV you will probably about double the mass given the drywall and plywood underneath. I bet you get at least 6 points from 2 layers of MLV to your floor, but not likely more than 7 or so just based on mass.
However, there is another benefit you will get if you put down two layers of MLV and seal it up with caulk. Basically, you are going to eliminate any sound leaks that you have today, which could give you a decent boost in STC as well.
So my point is, it is really hard to determine the exact STC jump you are going to get, but two layers of MLV should be substantial. (I bet in the 10 STC range).
There are postings on this board that contradict this, and claim that STCs simply add up (basically that you would get another 26 points by adding 1 layer of MLV), but those claims are just plain wrong and fly in the face of basic science. I wish I could give you a more specific answer, but let me know if you have more questions.
John Tower
: I'm thinking of installing a couple of layers of Mass-Loaded Vinyl under my carpeting. What kind of effect on the STC will those layers have? Say the STC of my floor/carpeting is at 38 now. If the MLV has an STC of 21 - and I apply two layers - how much will the STC go up?
: Also, what kind of effect will the MLV have on impact vs. airborne noise? Is the MLV more effective with impact or airborne?



 

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