Soundproofing between units?

Question

Hey everyone, currently living in a house-hack (over/under - we live in the upper unit). Original plan was to move on after a year, but we really like the area.

Problem is, it's a wood frame construction, and the noise transfer between the units is starting to bug me. Louder conversations can be heard as muffled speech, I often use the heat pump to drown it out. Social visits from either unit will cause a decent amount of sound to enter the other unit.

Considering living here longer, but we might address the sound issues. Does any one have any experience with this?

Hoping to mostly resolve speech/ect noises not impact as I know that is a different beast.

Planning on keeping the existing ceiling, but adding
-sonopan
-resilient channel
-5/8th dry wall

Would this make a noticeable difference? It will be a decent chunk of money.

Is it possible to just do the living spaces (living room, kitchen, hall way) and leave the bedrooms unchanged?

Thanks in advance!

Ryan Thomson · Answer

@Stuart Alexander

Those are some of the things I have tried when I converted my garage in Colorado Springs to a separate studio kitchenette. It was below the family room.

We did a sound proof board and then another drywall layer. We also insulated the space between the floor joists. It certainly helped some. It wasn't that expensive bc it was 400sq ft and it was already unfinished. You are going to have to tear down a lot of drywall just to put it back up. I would certainly get some estimates from local contactors before you go to far down this road.

Kenny Smith · Answer

@Stuart Alexander

Thanks for posting!  I got you on this..

So we've had the same issue with our up/down SFH house hacks.  The first and very easy thing you can do to help eliminate noise is insulate the vent exchanges.  There is this material we bought at Grainger (https://www.grainger.com/produ...) and then used this adhesive spray to line the ducts near each exchange (https://www.homedepot.com/p/3M...) A lot of the noise was coming through our return vent as well, so make sure not to forget that.  This insualation basically helps with noise dampening as much of your noise is probably traveling through the vents and right upstairs if all of the ducts are on one HVAC system.  This is a very cheap fix for that.

Another thing we tried, albeit not sure if it was worth the money, is you can get blow in sound insulation in between your floor joists.  Essentially an insulation company will drill a roughly 3-4 in hole in your drywall in between each joists and blow in sound insulation.  We used this (https://www.homedepot.com/p/Gr...).  It can be expensive as they will need to drill a lot of holes, insulate it, then you have to pay a drywalled to come and patch the holes.

Both of these combined has helped tremendously with noise though, we barely hear our downstairs guests.  Now to your point, vibrations from walking is a whole different beast and what I've heard works the best is if you re-do your floors upstairs, lay down some type of noise padding on top of the subfloor.

Hope this helps!  Let me know if you have any more questions.

Andrew Postell · Answer

@Stuart Alexander some of those things can help but that's a lot of work to reduce a few decibels. I have used the sound reducing panels (just a different brand) before and it does help but it will also be a considerable investment to make a real difference.  I might suggest with starting with some simple ones that you can hang on the wall to see how much difference it makes. You can even try things like area rugs too (but maybe you already have carpet or rugs down).  Check out this site and see if anything looks appealing: https://www.acoustimac.com/

Soundproofing between units?

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