Is a triple leaf better than nothing?

[junho]

I am building a woodworking shop underneath my patio.  Unfortunately it shares two walls with the suite that I rent out.  The existing walls of my house are 2x6 construction and from the outside in are hardy plank, insulation, then drywall.

I understand that a triple leaf can cause a resonance effect that can potentially make things worse and I understand that a double leaf is the better approach.  However, removing the hardy plank from my house is not an option.  So would building a false wall out of 2x4 and filling it with insulation (thereby creating a triple leaf) still be better than just sticking with the double leaf that is in place?

Would it make a difference if I stuffed the cavity full of insulation to eliminate the narrow air gap?

Thanks in advance for your help

[Randy S]

when we get into situations such as this which we can not avoid the triple leaf we will treat the center leaf first. Use the SSP foam mat 1/4" on the existing wall before building the new frame.

http://shop3.mailordercentral.com/supersoundproofing/prodinfo.asp?number=09-42720-PSA


Make sure the frame is at least 1/2" or more off the existing wall fill the cavity with cotton fiber insulation and attach Mass loaded vinyl barrier to the new frame followed by drywall.

http://shop3.mailordercentral.com/supersoundproofing/prodinfo.asp?number=09-00005-48