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condo · 12-17-2011, 08:06 AM

Yes there was a noticeable improvement immediately as would be expected. The sound was dampened a little. How much was due to the GG and how much was do to the drywall is of question but some of the low frequency noise was improved to the point it was not detectable by my ear which may be the GG's strong point.

Previously you had recommended "the introduction of a 4 1/2" air cavity." wouldn't that create what is known as the triple leaf effect?

**Ted White** · 12-17-2011, 08:45 AM

So a little noticeable immediate improvement. The existing wall is decoupled. You doubled the mass on one side of a staggered stud wall and damped that mass.

Damping alone can increase a staggered stud wall performance 5 points. You added damping + mass on one side so one might have expected a 9-11 point increase perhaps. A 10dB increase in performance would correspond to a halving of the acoustic energy.

This assumes no flanking, and walls, ceiling and floor = flanking opportunity. Given your assessment of the improvement as well as the fact that a decoupled wall was as problematic as it was to begin with points to flanking. Likely significant flanking.

The triple leaf effect that we avoid is diminished as the air cavity increases. If you can add a 4-5" air cavity you are getting out of the danger zone so your improvements will have a chance to pay off.

There are several third party certified lab reports showing performance expectations of the surface treated. However, if only 60% of the sound energy is passing through that wall, then clearly even a perfectly soundproof wall will only reduce the sound you're hearing by 60%.

All data points to significant flanking so I would recommend turning your attention from the wall itself for a moment and look at how sound is flanking around your wall. Again floor, ceiling and side walls. Pipes, ducts, in the side walls, in the floor or ceiling near the wall as well.

This assumes the damping itself was applied correctly and that any penetrations in the drywall were properly sealed, as well as the perimeter of the wall, especially behind the base molding.

condo · 12-17-2011, 10:33 AM

I understand but I am going to address the wall first. The sound may have been reduced by 15-20% and I have not reinstalled the ceramic tile yet which may have some benefit. The bathroom was the louder of the two rooms and is now about the same as the Master Bedroom before it sounded like the noise was coming more from the bathroom from the bedroom, now it sounds to be coming from the wall. So I'm hoping once I do the wall it will be at an exceptable level but will evaluate as I go and I may do the spare bedroom first to see since the noise level is not as bad in there.

Call me crazy but I am now thinking
Existing drywall + styrofoam layer + soundboard layer + styrofoam layer + drywall <--- not screwed into the studs but to the soundboard only.

You don't think the styrofoam would help eliminate vibration transfer?

Edit: I did seal the wall perimeter and all joints, attention to the area of the baseboard was required on the existing also.

**Ted White** · 12-17-2011, 10:37 AM

As long as you understand that you have significant flanking.

As I stated before, I suggest you stick with lab tested assemblies. There are many to choose from.

condo · 12-17-2011, 11:01 AM

Given the fact that the wall is more or less already decoupled what are some of the assemblies and are there any charts to compare results I could view?

MLV, GG and RC are outside of the budget.

condo · 01-05-2012, 05:31 PM

I ended up working on the second upstairs bedroom since it is the quitest I felt it would have the best chance for success.

I used a layer of styrofoam sheeting on top of the existing drywall then a layer of soundboard sheeting, another layer of styrofoam and finish layer of 5/8" drywall.

It has been several days now and I would estimate a noise reduction of 50% and I am fairly pleased with the results and cost.

I will evaluate more and post some observations later.

**Ted White** · 01-06-2012, 06:36 AM

Drwall secured with screws secured into the sound board only... May the force be with you

condo · 01-06-2012, 07:03 AM

I didn't realize how soft that soundboard was I had to secure the drywall to the studs.

artsy737 · 03-10-2013, 06:17 PM

I want to soundproof a wall between townhouse units. Could my concrete slab main floor be a conductor of sound and/or vibration as well or should I concentrate on the adjoining wall. Also, the wall is approx. 13' high.
Are there any other issues that I should be aware of with such high ceilings? Additionally, I'm relatively certain that our vent system is not shared, however, could there still be flanking through the vent system? I've never heard voices at all through the walls...only bass sounds/vibration.

**Ted White** · 03-11-2013, 06:03 AM

Concrete could conduct, but concrete conducts footfall noise (impact) better than airborne. Without all the details, it would seem that removing your drywall and inspecting the insulation, adding either a clip & channel system OR a second wall to decouple, followed by double drywall that has been damped.