bedroom common wall sound, please help

[joel]

Gee John, what kind of language is that from a "professional".  This is a forum for sharing information and experience, not cussing.
The simple soulution quoted in my post is based on the successes of hundreds and hundreds of real people in the real world.  Many of the published test results available for materials such as dry wall, insulaiton, quiet rock, green glue, etc. are ASSEMBLY ratings - not what the material by itself will bring to the solution.  They all present their respective test results with the tag line "numbers don't lie".  Well, to quote a lab tech at Owens Corning, "We can do anything in a lab".   Judge for yourself by the results, OK?

[johnbergstromslc]

Well, your job is to sell MLV but at $48 for a 4X8 sheet, I would never recommend anyone use the material in that configuration.  Mis-installed like that, it is, simply, a big waste of money.

[joel]

We don't sell 4x8 sheets.  We sell rolls.  Besides, John, you still did not answer the main question posed to you.  Have you ever tried the solution proposed???

[johnbergstromslc]

Well, MLV is $1.50 per sq. ft - same difference. 

No, I have never tried the 'MLV sandwich' solution because I've seen the results of acoustical tests that show that it's not a cost-effective way to go.  The decibel-per-dollar cost is way too high.  It's much, much cheaper (not to mention more convenient, not to have to wait for a product being shipped) to add a third layer of drywall to the wall, for a 50% increase in mass and a 3-4 point rise in STC, especially in low frequency TL.  MLV in between two layers of drywall can't match that. 

If a person feels he needs 3 layers of drywall for basic soundproofing, I would recommend that he first gut the wall, do some remedial sealing and insulating and decouple the wall with staggered studs or resilient channel before the double drywall.  Skip the MLV!

Now, as for Green Glue in between drywall layers, that is a different story.  I would whole-heartedly recommend that, if the situation called for it.     

[joel]

Well John,  I finally get to completely agree with one of your posts.  For the dollar your suggestion is very reasonable. 
Oh, by the way, my job is to offer customers all the soundproofing options - not to "sell" MLV.  We pass up sales every day when it is appropriate.  It has been the experience of my customers that the solutions they have used have given them the results they wanted to achieve, given their conditions.  Keep them "stats" and recommendations coming - we enjoy your input.

[thinfine]

I found a really good article which breaks it down with pictures and everything.  It seems to co-incide with several things that are being said here. In another post, I saw that a good sound level meter would be helpful in testing the issues.  Does this information seem correct to address sound issues coming through a wall?  Thanks.  I got the info formt his website: http://www.tmsoundproofing.com/store/pages.php?pageid=15

If you want to use visoelastic material (ie. Green Glue) for damping
Best Type of Wall
Wall Type:  Damped drywall (Green Glue sandwiched between 1/2" or thicker drywall) to help with resonance, ie. low frequencies
Decoupling: Double stud wall insulated with fluffy fiberglass insulation to help with high frequencies.

2nd Best Type of Wall
Wall Type:  Damped drywall (Green Glue sandwiched between 1/2" or thicker drywall) to help with resonance, ie. low frequencies
Decoupling: Staggered stud wall insulated with fluffy fiberglass insulation to help with high frequencies.

3rd Best Type of Wall
Wall Type:  Damped drywall (Green Glue sandwiched between 1/2" or thicker drywall) to help with resonance, ie. low frequencies
Decoupling: Sound clips insulated with fluffy fiberglass insulation to help with high frequencies.

4rd Best Type of Wall
Wall Type:  Damped drywall (Green Glue sandwiched between 1/2" or thicker drywall) to help with resonance, ie. low frequencies
Decoupling: Wood or metal furring channel (not resilient) insulated with fluffy fiberglass insulation to help with high frequencies.

5th Best Type of Wall
Wall Type:  Damped drywall (Green Glue sandwiched between 1/2" or thicker drywall) to help with resonance, ie. low frequencies
Decoupling: Resilient channel insulated with fluffy fiberglass insulation to help with high frequencies.

If you want to use conventional drywall
Best Type of Wall
Wall Type: Add an extra layer of drywall to one side of the wall and/or use thicker 5/8" thick drywall
Decoupling: Double stud wall insulated with fluffy fiberglass insulation to help with high frequencies.

2nd Best Type of Wall
Wall Type: Add an extra layer of drywall to one side of the wall and/or use thicker 5/8" thick drywall
Decoupling: Modern sound clips like Whisper Clip insulated with fluffy fiberglass insulation


3rd Best Type of Wall
Wall Type: Add an extra layer of drywall to one side of the wall and/or use thicker 5/8" thick drywall
Decoupling: Staggered Studs insulated with fluffy fiberglass insulation


4rd Best Type of Wall
Wall Type: Add an extra layer of drywall to one side of the wall and/or use thicker 5/8" thick drywall
Decoupling: Resilient Channel insulated with fluffy fiberglass insulation


5th Best Type of Wall
Wall Type: Add an extra layer of drywall to one side of the wall and/or use thicker 5/8" thick drywall
Decoupling: Wood or metal furring channel (not resilient) perpendicular to the studs at 24” on-center insulated with fluffy fiberglass insulation

[musicboy]

We are in the process of adding a second wall with insulation and the isotrax system.  Did you buy the place yet?

[bush2]

The wall is said to have an STC rating of around 55.  The part that concerns me is the connections at the subfloor and ceiling.