One night, a client was wandering through their yet to be completed renovation when he heard the neighbor's television through the wall of his master bedroom. He reported it was "as if it was in the same room." He explored further and found he could hear it on the floor above in the soon be bedroom of their 3-year-old daughter. To make matters worse, the neighbor reported hearing our workers as if they were “in her master bedroom” and that until then -- for 15 years since she had moved in -- she “had never heard the neighbors.”
Their first assumption was that we, Stratagem Construction, a home renovator in Chicago, had done something to cause this. This is a universal reaction. The home renovator is always at fault even if a bird house falls down in the back yard.
In this case, we hadn’t done much work on the party wall. We hadn’t opened it, rather, our work was limited to constructing a built-in along the wall. We had screwed into the 2 x 2's but not more. So we considered whether the built-in acted as a speaker adding sound transmission. But this theory didn’t account for why their child's bedroom upstairs had become noisier.
To better understand the situation, let me describe the party wall. It was typical construction separating our client’s town home from his neighbor. The central structure was a 6 inch concrete block. Each side was furred with 2 x 2's wood studs and covered with 5/8th inch drywall. This usually creates excellent sound protection.
Here are our general ideas for dealing with sound control and sound insulation issues (in Chicago):
1. Everything sounds worse in a quiet, empty house. There's no furniture to absorb the sound, nor are their other sounds to mask them. In addition remember that clients are very sensitive to anything unexpected. It makes a problem seem larger.
2. Everyone has a different sound tolerance. What may be hardly audible to you, the home remodeler (in Chicago), may be very irritating to them. The client by definition is right but it’s still important to have a thorough discussion regarding sound perception. A few talking points:
- People stop hearing things that are repetitive like nearby trains.
- Sound machines or fans can mask sound.
- Furniture, carpet, clothes in a closet all absorb sound and improve the situation.
- You can talk to your neighbor and work out quiet times as alternative to sound control methods.
3. No matter what method you use for sound control, it may not be effective. Sound is like water, if you block one way, it may enter another way. Chances are the more you do, the more likely you improve the situation. Be sure to show your client information on how sound transmits through and around walls. The more they understand how complex sound control is, the less likely they’ll be angry when the results are not as good as they had hoped.
4. Start your analysis by listening to the offending sound with your client. As a neutral observer, your listening will put their perceptions in perspective. If you can barely hear the sound that is annoying them, they’ll understand they’re very sound sensitive. In addition, you’ll understand their level of sensitivity to the noise.
5. Map out where sound is loudest. Have the neighbor turn on the TV and put a cup to the wall and your ear on the cub and start listing. It’s old fashion and there’s no fancy machinery, but it’s surprisingly informative. Check all the surface, floor, ceiling and walls.
6. Visit the source of the noise. If the neighbor has turned on the TV for you, go from your client’s bedroom to their bedroom on the other side of the party wall. This helps you and your client how good the party wall is at stopping sound transmission. Importantly, try to observe where the sound is being generated and spot how the sound is being transmitted to the party wall. Is the TV on the wall or is it across the room? Is sound transmitted through conduction or through the air? Are there speakers in the ceiling so some layers of sound protection are being circumvented?
7. Picture the construction between where the sound is created and where the sound is perceived. Use your knowledge as a home remodeler (in Chicago) to create a theory on how the sound is transmitting through various construction elements. Your theory should account for the sounds source and where the sound is heard loudest.
8. With a theory of how the sound is transmitting, consider sound control solutions. They have to be appropriate for your client’s space and budget. Can you add sound insulation? Can you build a second wall? Do you have room to put in a layer of elastomeric polymere and drywall? Maybe an unorthodox solution such as buying a carpet for your neighbor’s children’s playroom will get the job done.
9. Before embarking on any solutions, talk to your client and repeat every third sentence that you can't really be certain. Give him your cup and let him test your theory. Taking your time here is your best protection against your client holding you responsible for a poor result.
This is my Argonne National Laboratory nanotechnology cup that turns colors when ice tea is added to it, but any cup will do.
In this particular case, our client and I had the neighbor turn on the TV and listened together. I could barely hear the TV – it was not as described -- and my client admitted he was very sound sensitive. We observed that the sound traveled from the neighbor's master bedroom to master bedroom on the same floor in my client's unit. In addition, it also transmitted well to the floor above. My client was correct in his perception. We heard it in both places equally. When we visited the neighbor, we saw her TV’s speakers were in the ceiling. This meant that sound went along the joist spaces in her ceiling to the block where they hit wall without obstruction. They might also have been carried in the joists themselves. The vibration likely conducted across the wall into the furring studs and then up and down the wall equally. This explained the reason we could hear it upstairs so well.
We mapped out the sound again with our cup evaluating which walls required sound proofing most. This method helped exclude certain wall which saved our clients hundreds of dollars.
We opted for a thin coat of elastomeric polymere (green glue) which absorbs sound transmissions in multiple directions. We cover the existing drywall with the elastomeric polymere and screwed in a 1/4 drywall sheet. It would be nifty if we could test the sound transmission immediately, but elastomeric polymere needs a minimum of 10 days to cure with maximum sound dampening after 30 days. After refinishing the wall we put the built-in unit back in. We'll see how it works.