At Metro NY Insulation, we have very high standards for the sound blocking capability of a good wall. Our “good” is probably higher than any other company you will find. We don’t accept minimum compliance with local building codes, you shouldn’t either; with reliable, proven products you can obtain very good results, and stay within your budget.
For soundproof wall construction, we will refer to the Sound Transmission Classification (STC) as a measurement of the walls ability to block noise. A typical residential wall has an STC of 38-40, a normal commercial wall may have an STC 42-45. For a reference point that will make your choices simple, the minimum standard for a HUD financed public housing project requires an STC 45 between units.
For new construction you have a couple of easy steps to insure a good performing wall or ceiling assembly.
Use cellulose insulation in the cavity; thickness according to the depth of the cavity R-11 for 2×4 studs, R-19 for 2×6 studs. Using more expensive insulation will provide no measurable improvement in the STC rating.
Option 1: Use 2 tubes of Green Glue between 2 layers of sheetrock, on one side of wall. Green Glue is applied in a random pattern, on the second layer of sheetrock, and then everything is screwed together. Green Glue Installation
Option 2: Install a UL Rated Soundproof Barrier on one side of the wall, directly attached to studs, then install 5/8″ sheet rock over the barrier. You must use Soundproof Barrier on the studs, before sheet rock is installed; the product is not intended to be used between sheet rock layers. Soundproof Barrier installation.
The details in constructing a “good” soundproof wall are very important. Every outlet box and switch box must be covered with a Seal Tight Putty Pad, There should be a small gap at the perimeter of the wall; this will be filled with Silenseal Acoustical Sealant.