Soundproofing your condo

by Bill and Kevin Burnett

Question: I finally saved enough money to buy and install a home theatre in my duplex condo. The picture on the big screen is amazing and the sound from the six speakers is even better. I have three front speakers and a subwoofer on the floor and two surround speakers mounted in the ceiling. I love it.

Unfortunately, my neighbour doesn’t feel the same way. Whenever a movie soundtrack gets a little loud, say the Martians attack or the earthquake and tidal wave hit, she pounds on the wall. Once she even came over and threatened to call the police.

What can I do? I want to be a good neighbour, but I also want to enjoy my new toy.

Answer: We doubt you’ll be able to fully soundproof your condo, at least not without hiring an engineer, a contractor and spending a whole lot of money. But there are a few steps you can take to dampen the sound and keep your neighbour at bay. Some are relatively inexpensive, while others are free.

What’s bugging your neighbour is vibrations from sound waves that strike your wall and ceiling, then reverberate through the wall and attic to her space. Your goal should be to isolate and reduce these vibrations.

First, you should build a new sound wall. This will be the most time-consuming and expensive job, but it’s pretty much mandatory, especially in a condo.

Take these steps:

1. Build a standard two-by-four wall with top and bottom plates and studs on 16-inch centres. Make sure it’s parallel to the existing wall, leaving one to two inches of dead space between the two walls.

2. Reroute your power into the new wall. Installing a two-inch flexible conduit will make it easier to run your wiring to components and speakers.

3. Install the insulation — fibreglass sound attenuation batts that are designed specifically for use in interior partition systems.

4. Finish the wall with sound-dampening wallboard. Make sure any seams and cutouts for outlets are sealed up tight. You should use special sound-dampening products for this job. These materials will cost up to four times more than a standard drywall wall, but they’re absolutely worth the money.

Once your wall is built, there are three more little jobs you’ll need to do:

5. Sound from your in-ceiling surround speakers is probably leaking into your neighbour’s space through the attic. Consider adding speaker enclosures here. A number of choices are available. Start by doing a Web search for “in-ceiling speaker enclosures.”

6. Low-frequency sounds from your subwoofer may be a major source of your neighbour’s headaches. If your sub is against the common wall, move it as far away as possible. No need to worry about this degrading the quality of your sound.

7. Finally, make certain your speakers, especially your subwoofer, do not sit directly on the floor. Use speaker stands or do a Web search for “sound isolation cones.”

These steps won’t solve your problem completely, but if your neighbour is at all reasonable, you should be able to co-exist. Why not nuke up a batch of popcorn and invite her over for the next feature presentation?

— Inman News.