bad sounproofing job

[andylek69]

Recently had someone in to soundproof a party wall,he's used all the correct materials,ie track and stud,resi bar etc,but ive noticed that he's then fitted the 2 layers of plasterboard right upto the walls,floor and ceiling with no gap around for acoustic sealant
Wil this completely nullify everything,would it be worth me ripping off the plasterboard and trimming boards back and then applying the sealant
I was going to do it all myself in the first place,maybe wishing i had now

 

[Deluks]

Could probably 'scribe shave' it back using a stanley knife blade held against a thin piece of tile or ply etc 5mm max.

More importantly, has the resibar been correctly installed?

 

[andylek69]

Thanks for reply
In terms of resi bar there are no screws going thru studs,so there are no short circuits as such(position of studs marked on floor so i can see this) and they were installed the right way up,the ends do touch the adjacent walls though,its quite difficult to cut thru 25mm of plasterboard when its fixed to wall,im just wondering if its worth the effort of taking down the boards to trim them,how critical is the gap and sealant? as i still get some flanking noise thru adjacent walls anyway,would i be wasting my time and effort

 

[freddiemercurystwin]

Why not hire one of these baby's?
http://www.kennards.com.au/index.ph...er&lvl=2&PHPSESSID=rogd7pp9mvngcdho9jfd7lnj13

 

[andylek69]

Thanks thats a great idea,but looks a bit overkill for my usage,but it got me looking at similar products,think i might get myself a Bosch PMF 180 E,looks quite handy and ive got loads of other jobs where this would be very useful(or would have been!!)

 

[ajrobb]

The main things are to eliminate air leaks (direct paths), stop energy getting into the 'floating' plasterboard and to absorb energy in the cavity (with mineral wool). The impedance at the edges is likely to be much higher than the centre of the wall so the energy flow will be reduced by the mismatch - energy does not flow well through mismatched impedance.

I suspect the acoustic sealant is there to seal the direct paths and prevent cracking as the plasterboard floats. I doubt you'll hear much immediate improvement by installing sealant. If he missed out the acoustic mineral wool, you could get some improvement by removing the plasterboard to install mineral wool and sealant.

 

[Nige F]

The main things are to eliminate air leaks (direct paths), stop energy getting into the 'floating' plasterboard and to absorb energy in the cavity (with mineral wool). The impedance at the edges is likely to be much higher than the centre of the wall so the energy flow will be reduced by the mismatch - energy does not flow well through mismatched impedance.

I suspect the acoustic sealant is there to seal the direct paths and prevent cracking as the plasterboard floats. I doubt you'll hear much immediate improvement by installing sealant. If he missed out the acoustic mineral wool, you could get some improvement by removing the plasterboard to install mineral wool and sealant.

wrong button ...Interesting post tho`.

 

[ajrobb]

I forgot to mention the effect of constrained layer damping. A damping layer is glued between two layers of plasterboard to deaden any vibration that gets into the resilient skin. It relies on the shear between the vibrating plasterboard layers to put energy into the constrained layer, where it is converted to (a tiny amount) of heat. Any mechanical fastening (screw/nail) that goes through the constrained layer will reduce its effectiveness. However, some mechanical fastenings are generally required.

My background is automotive noise rather than building noise.