Shared joists - floor isolation ideas?

[decater443]

Hi all,

I am trying to isolate as best possible a room in my apartment from my neighbour. My room is bordered by them on two sides and we're separated by only 2" of old blockwork so we can talk through the wall - not ideal - reminds me of Office Space. One of the key issues in this problem is we have shared timber joists; our separating party block walls have been built on top of common floorboards when the building was divided - apparently all the rage in the 60s.

I have already cut the floorboards my side and am now soundproofing the walls. Once done these will be: existing 2" brick - 25mm gap - 100mm stud filled with fibreglass/rockwool - genie clips - 15mm drywall + Green Glue + 15mm drywall.

As we will still share joists I know that impact and perhaps airborne? noise will run under the wall & also into the new 100mm stud frame, fixed to the joists, hence I have opted for genie clips to help isolate the new drywall from the frame.

Once the wall is done, any suggestions on how I can best stop noise already in the joists coming up through the sub-floor on my side? It's currently 16mm flat edge floorboards; I was thinking of sealing the floorboard gaps with acoustic sealant then laying either a rubber underlayment or phonewell (http://www.phonewell.co.uk/Soundproofin ... loors.html) on top, then a decent underlay and carpet. Some sites suggest tecsound 50 first to add mass but I'm dubious about MLV type products. Or do I need to look at a more elaborate floating floor?

Many thanks for any views & suggestions (other than to move out!)

Cheers!

Tom

[Soundman2020]

Hi Tom. Please read the forum rules for posting (click here). You seem to be missing a couple of things!

existing 2" brick - 25mm gap - 100mm stud filled with fibreglass/rockwool - genie clips - 15mm drywall + Green Glue + 15mm drywall.

If you use clips, then you also need hat channel! Clips aren't mush use all by themselves!

Once the wall is done, any suggestions on how I can best stop noise already in the joists coming up through the sub-floor on my side? It's currently 16mm flat edge floorboards; I was thinking of sealing the floorboard gaps with acoustic sealant then laying either a rubber underlayment or phonewell (http://www.phonewell.co.uk/Soundproofin ... loors.html) on top, then a decent underlay and carpet. Some sites suggest tecsound 50 first to add mass but I'm dubious about MLV type products. Or do I need to look at a more elaborate floating floor?

How much isolation do you need (in decibels), and what frequencies do you need it it? Is it impact noise? Intermittent? Continuous? Without knowing that, it's impossible to say.

- Stuart -

[decater443]

Apologies Stuart - hopefully I've addressed those; thanks for replying.

Yes, I'm using hat channel with the clips - good spot The wall is pretty much nearing completion so I'll know soon if it's made any difference.

Reference isolation, my goal is to:

a) Reduce talking/coughing/laughing from next door to that of a whisper. So I believe that's ideally 40dB isolation but I'm guessing 20-30dB is a more realistic target. If I can stop following their conversations and biting my lip from wanting to join in that would be good. If I stop hearing them at all it would be a miracle; night time is obviously worse but that's life. I'd also like to play music at a normal residential level in my room without thinking about it being heard next door...

b) Reduce impact noise from the banging of kitchen cupboards and walking along the adjacent corridor. The easiest solution here is probably at the source - ask their landlord if I can screw down their floorboards and install better underlay. However, as I have the floor up I figure I might as well do everything I can my side first as it shows willing. Unfortunately I haven't measured the levels yet; I have a meter in the mail to me.

Both issues are intermittent but consistent, fully dependent on when they are home (they work shifts).

Thanks again for your advice.