Author Topic: Own a 3 level condo - soundproofing the basement  (Read 1835 times)

Own a 3 level condo - soundproofing the basement
« on: March 12, 2019, 11:09:46 PM »
Hey all! First post here. I'm sorry if I'm not adhering to any rules I may have missed.

I'm looking at DIY'ing (inexpensively) soundproofing for a condo basement in Canada. I'm familiar with the basic concepts of soundproofing (mass=blocker, resonance is bad, viscoelasticity, etc), but need advice here.

Basically, I have adjoined neighbors to the east and west. I'm planning on making the basement a theater room (on a budget, since we both work part-time to support ourselves in volunteer work) soundproofing the basement walls against my neighbors to at least provide some level of sound dampening. Not the ceiling, since I won't be able to get access up there without major renovations, and I'm hoping the fact it'd need to travel through additional walls (the ceiling, floor, and then neighboring walls) will help avoid the need to touch the ceiling. The east wall is a straight 8' by about 10-12' stretch. Along the west wall has my mechanical room - this is basically a room within the basement, and this allows me currently to access the inside of that wall to insulate. I can also add drywall to the walls INSIDE the mechanical room since there isn't any as of yet. Total stretch would be about 14'-16', excluding the mechanical room?

Basically, I'm down to 3 options. I'm looking for best "bang for your buck". I'd like to watch Interstellar, for example, at reasonable volumes with a proper soundsetup without worrying about my elderly neighbors in their upstairs bedroom. I want to mitigate as best as I can.

1. Tear down the east wall, add insulation (planning to use Rockwool), and replace with new drywall. Instead of 1/2 drywall ($12/sheet) or "soundproofing" drywall with a viscoelastic layer ($60/sheet)", I'm planning to use 5/8 Type X (firecode) drywall ($17/sheet), which is 100lb a sheet vs 40lb a sheet for regular drywall. The drywall will be well over 1lb/ft. Then insulate the back of the west wall with Rockwool. Leave the west wall itself as is. Not sure if there's resilient channel?

2. Tear down both the east and west walls, add Rockwool, and replace both walls with Type X drywall.

3. Leave the existing walls and add a new layer of drywall to both the east and west sides, possibly with MLV in between (most expensive by far, $241/100sqft from a local supplier where I pickup, so probably $500+ just in MLV). I would have no idea how to do this, or what hardware to use for spacing the drywall.

I'm not familiar with "green glue" or any other specialty building products for sound reduction. My expertise is in auto sound reduction, which isn't really "expert" by any means. What's my best option here...?

The existing flooring is carpet, and I'm planning on redoing the floor with hardwood as well. So if adding another drywall layer is best, how should I do the flooring...? First? Doing the flooring first might be slightly problematic since we have a painter already working through the house, I'd like to get this done before he gets to the basement (within a couple of weeks), and this will be a job I'm working on almost entirely in my off-time (evenings).

Randy S

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Re: Own a 3 level condo - soundproofing the basement
« Reply #1 on: March 13, 2019, 03:14:17 PM »
Is the basement poured concrete or cinder block?
if so the ceiling is where you need to focus most of your effort, if not I promise your walls will have little effect on what your neighbors hear.

I have done this mistake before, look at it like shaking a soda can up and popping the top..all the sound will go up and since that will be the area of least resistance they will hear your noise.

decoupling and mass will be the primary factors on this build.
speed of sound through air is 1129 fps but through wood framing is 13,000 fps

Why dont you give me a call direct and we can discuss.

Best Regards,

Randy S.