Q. I live in a townhouse that has a wall that I share with my neighbor next door. Can I inject blown insulation into the wall space between our dwellings to reduce noise from one space to the other? I am very happy in my townhouse and enjoy my neighbors, but I would like to hear less of them at times and I am sure that they feel the same. Any suggestions? Freeda, B., San Mateo.
A. We appreciate your need for privacy and understand that a soiree next door can be grounds for a war on your end. Standby, relief is on the way.
Injecting blown insulation into the wall space between the dwellings is an excellent idea. Unfortunately, while it is one of the least disruptive and most inexpensive means of dealing with this problem, it also happens to be one of the least effective. It is nonetheless the point at which to begin since any other solution that we might recommend will also include this as the first step.
The most effective way to deal with this problem is by increasing the density of the space between the dwellings. There are several ways in which this can be done.
The first is by installing decorative wall panels, which are engineered to absorb noise. One of the major manufacturers of these products is the Homasote Corporation. Their panels come in a variety of finishes from cork to grass cloth and are sure to meet virtually any decorating need.
Another way to diminish the transfer of noise is by installing one or two layers of 5/8″ gypsum wallboard over resilient mounting channel that is attached to the existing wall horizontally, on 24″ centers. The resilient channel will provide air space between the layers of wallboard and lessen the amount of noise transferred through vibration.
Where noise is a real problem, a new and separate party wall can be constructed that incorporates air space, insulation, and multiple layers of gypsum wallboard. The disadvantage here is that it is quite an undertaking and depending upon the space can be quite costly. It can also make what is already a small room even smaller.
Consult an architect or acoustical engineer if more information is needed.