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So this is a 1/2" total thickness product? If so, I really recommend to increase the mass by adding a thick sheet of drywall behind that finished material.

Are you planning to incorporate acoustic treatments on the walls? Often the walls are completely covered with treatments. In that case there's not much use in applying a finished panel like you're showing.

Just trying to fully understand what you're goals are.

Thanks,
 

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Discussion Starter #62
So this is a 1/2" total thickness product? If so, I really recommend to increase the mass by adding a thick sheet of drywall behind that finished material.

Are you planning to incorporate acoustic treatments on the walls? Often the walls are completely covered with treatments. In that case there's not much use in applying a finished panel like you're showing.

Just trying to fully understand what you're goals are.

Thanks,
The total thickness in wall and ceiling is 1/2" DW+ 1/2" DW +1/2" MDF= 1.5".
This is what I have found out thanks to all posts in the thread, and because of limited space.
The acoustic treatment is the last thing I do, and I shall not cover the walls completely.
Grateful for your participation Ted:T
lgl
 

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So this is a 1/2" total thickness product? If so, I really recommend to increase the mass by adding a thick sheet of drywall behind that finished material.

If I may ask, what would be the difference between 2: 1/2" and one thick sheet? I mean, what is the difference in terms that I can understand as a builder of rooms.

Granted I wouldn't put the MDF on the inside of the room, but it is treatable:) It would be better situated as the first layer, but that's just from what I know.
 

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Well, that's a really great question.

From a mass perspective it's a wash, let's just say. Two 1/2" pieces = the weight of one 1" panel. But splitting that mass up gives you the opportunity to damp the panels with a damping material.

If you were not going to damp, then having two dis-similar thicknesses of the material would break up resonance better.

Three layers of 1/2" mass (damped) is better than two 3/4" layers of (damped) mass, which is better than a single layer of 1.5" undamped mass. Why would three thin layers of damped mass be better than two thick layers of damped mass. Why?

Multiple dmping layers work better than a single layer. Even if the total amount of damping material remains the same.

Also, people use MDF on walls all the time, especially on the recording studio side of things. It's just an awfully expenside source of mass. We often recommend using a 7/16" OSB, then 5/8" or double 1/2". This gives you a nail base everywhere later when studs are hard to find
 

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That's a bit of a misleading recommendation they have and certainly not generally heeded advice. Otherwise we'd all be building our walls with lighter 1/2" board. But we don't (unless like lgl we use multiple 1/2" layers)

Mass law is a law, and 1/2" and 5/8" drywall are both sources of mass. Heavier 5/8" will outperform lighter 1/2" if we look at the larger sound spectrum.

One conclusion they derive is to use denser and thinner board. Technically, this is a great recommendation. The thinner panels allow more flex = more internal friction = more damping. Vibration is converted to heat. This is a good thing. And they pick up on the fact that 1/2" board is denser than 5/8" and thinner (flexible). However, 1/2 while more flexible and more dense is also lighter. And that it what swings the pendulum back in favor of the 5/8".

I also think they were considering the data produced from 16" OC wall tests, which are inherently stiffer frames (less flex, less internal damping) vs. the more flexible 24" OC framing. If a 16" stud wall is being used, the 1/2" gets closer in performance than 5/8" because it can flex better on a narrow 16" stud spacing than can the stiffer 5/8".
 

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Thanks for the verification. I think the National Research Council of Canada is a gold mine of information for audio related builds for people that choose to use it.
 

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Wow Ted, that is some good info. So if you were designing the "perfect" (but reasonable) wall, what would it be? 1/2 DW", green glue, 5/8" DW on a 24" OC frame? Would using different thicknesses out weigh additional mass of a 5/8" X 2 wall?
 

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Hi Patches,

I should mention that if you damp the system with a damping material, the whole 1/2" vs. 5/8" goes out the window. A damping material will damp far more efficiently than the board itself,

Given that, what I would recommend for a single stud wall (you mentioned) is 24" studs and double 5/8".

I would not recommend a single stud wall, however. A single stud wall is still coupled. I would recommend at least a staggered stud, and preferably a double stud wall to introduce decoupling.
 

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Ah yes, I was assuming an isolated wall. Another crazy question, what about using green glue between the studs and first layer of drywall as well as between sheets? Any benefit?
 

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Intuitively damping material would prove beneficial on the edges of studs and joists. There's insufficient surface area and little damping occurs there.

When used on a much larger surface area between sheets of drywall very efficiend damping can take place.
 

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Discussion Starter #75
There was bad weather:yay2:, so I worked a little inside. cut 1 inch of the roof beams in order to gain more headroom

takbjelker 002.jpg

To compensate for the weaker beams I glued on the reinforcement

takbjelker 003.jpg
 
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