• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Wall between neighbors thick enough, or do I need more insulation?

Rubberducky

Member
Joined
Jun 30, 2021
Messages
29
Likes
8
Soon I'll be moving into a new house where I want to set up a home theater.

The house has direct neighbors on both sides, but is relatively new (built +-10y ago). Between the me and the neighbors, there is 2x 15cm silicate stone (1750kg/m3) separated by 2 cm mineral wool insulation. The sound transmission loss, according to this site is:
Frequency [Hz] Transmission loss [dB] 31.25 37 62.5 46.94 125 65 250 83.06 500 101.12 1000 119.19 2000 137.25 4000 152.25 8000 164.29 16000 176.33
I would like to know if these are "good" values, or if I should be looking into adding extra insulation in between? When I measure my music volume I currently enjoy when it's a bit louder, I get +- 70dB, measured with an Android app. Not sure if that is relevant.
 
Check Quietrock, I've installed it and the claim it absorbs the same sound as 7 sheets of regular sheetrock is really true. If you have access to it on streaming, Holmes on Holmes did an episode where they installed it and tested with a meter. Getting drywall the same thickness as what's there isn't hard to replace, just cutting the outlets and painting.
 
You may also want to look at the STC rating, which is based on the type and depth of the studs, the type/ thickness of the gyp board on each side, and the type of insulation in the cavity. Granted STC is something we use here in the US, but they may be an equivalent where you are at.

Your description of the wall does not indicate the type of studs. At only 20 cm that is just a ~3/4 inch cavity. Is it more like a 90 mm cavity, with just 20 mm of insulation in it?
 
I’ll tell you a true story. I live in a 3 storey end town house. A few years ago I installed a new 7.1 cinema system on the top floor, back bedroom. The sub was an SVS-SB2000, and whilst I’m a cinefile, there’d be a fair number of action and Marvel films for the kids, played at…ahem…reference level.

Only a short time after installing it, I found that my one of my neighbours sons was getting married. They moved into the bedroom sharing a wall with my cinema room (living at home to save a deposit for a house). Not long after a baby appeared.

I was very worried, as I’d had a cinema room in there before, decent (though not as good) sound system, and occasionally the (previous) neighbours would hint that we might want to tweak the volume.

But with the new system there was never an issue with sound, we never woke the baby, or stopped it getting to sleep.

After a while I discovered why. They had built in wardrobes on the adjoining wall, obviously full of clothes.

Now the bottom floor, back of the houses are our kitchens, and Sue (neighbour) said she could hear the films loud and clear if she’s making a cuppa.

I suspect part of the help may be that our houses are decided by large, thick breeze blocks - I know American houses can have a different construction.
 
Thanks for the replies already. This is a European house, and there is no drywall / studs in between. It's just a 15cm thick stone wall (silicate) on the outside of my house, the same on the outside of the neighbouring house. And between them is a 2cm separation filled with insulation. My current idea is that the sound will be damped quite a lot, but that bass peaks might be an issue.
 
The problem in your case is how compressible the insulation in the gap is, because of the mechanical coupling between the walls. Styrofoam can be quite incompressible.
 
Seals Direct in the UK sell sound insulating sheets comprising a layer of lead between 2 different thicknesses of expanded rubber foam.
Catalogue can be downloaded from here.
 
Back
Top Bottom