Acoustic insulation in wall cavity?

Hi all I have built the first stud wall of a double leaf construction mixing room wall and would like to know if it is that critical to cut the acoustic insulation to fit in the cavity between studs and noggings? or if you could just lay the insulation over the frame in betwwen both walls and affix it to keep it steady? I am using a product called tontine Acoustisorb 2 and it is very difficult to cut, so it would save me a lot of time if i could literally roll the sheets over the whole inside of the frame and use fasteners to keep it in place? Any thoughts anybody?

You get a few db more isolation if the insulation rests against the inside panel of a wall - this dampens the panels which improves the loss through the panels, so overall performance is better. You also improve music frequency isolation by staying under 48 kG per cubic meter in insulation density, and completely filling the walls. Hope that helps, sorry it isn't what you wanted to hear... :? Steve

The truth, the whole truth, and nothing but the truth! Thanks for the info Steve..... So would it then be benificial to only put one layer of insulation against one of the inside walls instead of both? Or would i be wasting my time and money if i cant do both? I live in a fairly quiet country area, so extreme isolation is not "THE" most crucial element. Let me put it another way Steve if i may: If i cant afford to line both inside walls of the doulbe leaf wall construction, would it still be worthwhile putting the one layer of insulation fastened over the inside of one wall? or would it be a waste and therefore if i cant do both then i may as well not bother to do any? I am not quite sure either what you meant when you talked about the "under 48 kg per m3" thing.....

Any insulation (other than closed cell foam) is better than none, so if you can't afford enough to completely fill the wall frames between the two leaves of wallboard, any you can put it will help. In that case, I would probably put the insulation against the inside of the wall toward the mixing room - The wierd numbers refer to the density of the insulation in kilograms per cubic meter - that spec is normally either shown in kg/m^3, or in pounds per cubic foot (PCF) - for in wall insulation, you want between 2-3 PCF, which translates to 32-48 kG/m^3 - this density gives the most even sound reduction inside a wall... Steve