Hey everyone, it's me Bimmeup, the one who started the thread.

I guess this turned out to be an exciting thread afterall and very informative.  As for the Quietrock use in my home theatre, I did decide to use it since I'm in the construction phase and it seemed cost effective to me to have a drywall replacement than to put the cost of labor into resilient channels and layering the room with all sorts of other things.  And yes, in new construction, the Quietrock is used in place of drywall and is not layered over existing drywall unless you have an existing room where you want to use it!

As for me, I wanted the room to be as quiet as possible both from inside and out since I have a family of 5 kids!  My main goal is to be able to have friends over and go into the theatre to "Rock Out" until whatever time I want and not worry about waking up my wife and kids who are upstairs.  And after researching every method that's out there, it seemed to me (and I could be wrong) that Quietsolutions was the best "tested" method out there.  It also seemed to me that a lot of companies are out there trying to sell their products as sound deadening and sound absorbing, but just don't have any testing to back it up. 

So, in a nutshell, I'm giving it a go!  I'll also let you know what I think when it's up and running in about a year from now!

And hey PICKY, it's me Matt from Arizona.  I probably should have put that on my signature from the getgo!!! 

Anyhow, I'm out


Bimmeup
Matt

Consider double 5/8" drywall and a field application of damping compound. The resulting wall / ceiling will be more massive and less than 1/2 the cost.

Bimmeup:

  Essentially, the Quietrock is used in place of drywall and if used according to the spec sheet, can have a STC rating of as high as 80.

Matt

 

STC ratings are usually given at various frequencies. What really matters is how well it blocks at the lowest frequencies and most STC rating don't go down low enough and the ratings also depend on how they measured it. Appropriate construction principals still apply and are your first best defense against sound transmission.

STC is a single number and represents an average reduction measured at several frequencies between 125Hz and up to about 4kHz (I forget if it is 4 or 8kHz).

The notion of an STC rating of 80 for this type of product is fanciful at best.

For practical reasons, at low frequencies you will probably need to rely on adding mass (double sheets of drywall), staggered stud construction (look it up) or a layer of green glue sandwiched between two layers of drywall (as mentioned above), or limp mass loading (essentially a rubber sheet between the studs and drywall).

 As with most things, proper implementation of these techniques is critical. For instance, if you starting cutting into the material for recessed lighting, then you have just wasted a great deal of money.

Let me underscore Art's comment: getting good attenuation (or absorption for that matter) at the lower freqeuncies is especially difficult

Agreed. The biggest driver here is mass. The problem with factory-damped drywall is it's a lot of $$ relative to the final mass. Field-damped drywall uses double 5/8" resulting in a much less expensive and more massive result. Field apply for higher performance at a lower cost.

We are probably in agreement. But let's be clear for others. Doubling the mass (eg double sheets of drywall) is very effective for attenuating sound transmission at higher frequencies. It is less effective at lower frequencies.

However, a layer of green glue between the sheets of drywall (it is an adhesive that remains flexible, similar to sub-floor adhesive) will provide some dampening. It is this dampening that further helps minimizing sound transmission at the lower frequencies (in addition to the increased mass). Using this technique for dampening (and there are others also) also helps to absorb low frequencies (similar to a bass trapping).

Decoupling the large mass is key for LF isolation. The primary low frequency resonance point of the new partition must be significantly below the potential sound waves it will encounter in order to have a shot at containing them.

Am I the only one that noticed this was a 6+ year dead thread that got bumped by a bot?

I later noticed this, but by then there were already other replies... I did report that post as well as another as SPAM, but no reaction from mods.

_benjammin:

Am I the only one that noticed this was a 6+ year dead thread that got bumped by a bot?

Ya the only time a bot is good.  

But I must ask while I am here, My ht room mainly has concrete walls so for sound proofing through them is not a big issue.   But sound proofing through the celling to the upstairs is a issue.  I was planing on use 5/8 drywall, but I was looking at other things I can add that will help as well, such as adding a rubber membrane, or even using some of that green glue everyone has been talking about on the rafters that the 5/8 drywall will attach to.  I will have to check prices but it might be more cost effective to add the second layer of 5/8 drywall then to use a rubber membrane.  I all ready priced out the green glue so that isn't a extra cost.  But I was told just adding any r value insulation will make a dramatic deference.

Membrane would be used on top of the floor, not from below

So just going with double layers of sheet rock with green glue would be best. Is there anything that can be added In the rafters between the floor and celling, that would help such as fiberglass insulation or something of the sort.

If you have impact noise, you might consider the following:

wow did you draw that up, I take it the green damping material is green glue, what is the dyrwall furring channel oh wait the furring channel would be like furring strips to attach the drywall to.  I have seen the isolation clips that makes since. I would think you would need a solid layer of the green glue so would/could you but a 5 gallon bucket with a roller to apply.  The hardest part would be to install the strips of drywall between the rafters over all the duct work, but is a very good idea.

This is a very popular solution because it's very comprehensive. You damp the subfloor where the vibration starts. You would not use a roller, and instead use a Speedload.

Drywall strips is pretty fast if you leave the drywall strips 1/4" narrower than the joist opening. They fit right up there quickly.