Soundproofing of apartments?

4 Replies

I have a duplex that is divided up by floors: apartment 1 is on floor one and apartment 2 is on floor two. I have an issue with sound travel between the two floors. I got one of those dreaded 10:30pm tenant calls last night with complaints on the sound. I have had this property for 7 years, and, in general, the issues don’t present themselves if the tenants are going to bed around the same time. The bottom tenant is original and doesn’t complain much; until this last tenant moved in. She tends to goto bed around 9:30-10:00, but the tenant above her has put their office in the room above the 1st floor bedroom and will work sometimes until 2am. No issues except she will use a rolling chair, may drop things, may play music, etc. as much as I try, they just can’t seem to get along. I am curious about different methods to address this issue - soundproofing/dampening, ask them to move their office to a different room, get new tenants, etc. I had looked into having insulation blown into the ceiling but am not sure if it will be very effective. Any help is appreciated! Josh

My first property was a top/down duplex in which I was the lower unit. I really, REALLY wanted to punch the previous owner who added the 2nd floor in the face for not putting in ANY kind of insulation or isolation clips on the 1st floor ceiling after living there for 3 years. These problems will keep coming up, and the only real way to deal with it is to fix it.

I am an architect and a builder, so through my research the best thing to do would be to blow in cellulose into the ceiling cavity, and then install sound isolation clips and install another layer of 5/8" drywall. A large project if you ask me, with little to no gains in rent produced. You can also forgo the clips and just do the blown in with another layer of 5/8" drywall with green glue sandwiched in between and that would be my recommendation. In your area, you could probably get the project done for about $3-4k when all is said and done. But again, with minimal increase in rent. It will keep tenants longer however.

Hi @Joshua Mast ,

@Shaun C. 's suggestion of isolation clips on the ceiling of the 1st floor and blown in insulation is a great solution, and how we detail most multi-family buildings today. We also install sound isolation mat under the finish floors, and there are some very specific details to how this should be carried under the wallboard to create continuous isolation.

Another GREAT solution is to carpet the floor of the office on the 2nd floor with plush carpet and a thick carpet pad. It will cost way less than redoing your ceiling below. and will get done much faster with much less disturbance to the tenants, and in the end will probably be the most effective way to mitigate the sound. 

There are 2 components to mitigate when trying to dampen sound: transmission & reverberation. Sound travels through dense materials much easier than it travels through non-dense materials, but it will echo through empty space much easier than it will echo through a solid mass. To reduce Transmission, measured by STC (Sound Transmission Class) you what to decouple adjacent surfaces and increase their mass. That's what the isolation furring and adding a second layer of gypsum to the ceiling does. To reduce reverberation, which we measure with NRC (Noise Reduction Coefficient), you want to baffle and absorb sound that's bouncing around in a hollow cavity, like between the floor and ceiling. That's what the blown in insulation does. 

Carpeting and pad takes care of both to some extent. For one, it's going to separate the striking surfaces (shoes, wheels, dropped pens) from the transmitting surfaces (the hard, dense, subfloor). Secondly, it's going to help dampen reverberant sounds (like talking) by providing an absorptive surface.

I would start there, and see if it helps. If there's still a major problem, time to rip out the ceiling and try again.

Thanks for your responses. I have thought about both in the past and am going to attempt the carpet plan first, as it is much simpler and cheaper up front. If the tenant downstairs moves out, I will probably move forward with the insulation and drywall solution.

This site as a lot of good things.  More robust but I would try the others first.

Here are some details for flooring and ceilings within this pdf link.   See pages starting at 67.   This as some good pictures too.  Adding acoustical insul between the floor joist to the under side of the floor works so. But you have you to tear a lot of ceilings down for little value added.

I would also echo what the others have said.