I've recently bought a studio in an 80s flat building which has been built with concrete plates.
The problem: Crazy upstairs neighbor + wife + kid + a big dog. They make a whole lot of noise, especially impact noise. They throw things at the floor (probably the dog and the kid) and I hear a lot of steps and vibrations and loud bangs.
So my question is: How do I insulate the concrete ceiling, can I just stick high density foam on it? Will it do the trick for impact noise? I've found this PST 90 KG/ m3 foam on which I should probably add a drywall. Will it work for impact noise? I'm well aware that 100% noise reduction is not possible, I'd ideally hope for a 50% noise reduction.
Thank you for taking the time to read my post! I am eager to read your replies.
To do it properly you'd need to add a new suspended MF ceiling under the existing one. It's important that is is suspended so that it has minimal connection to the slab above. If it isn't, impact sounds will just transmit to the new ceiling. This would then need two layers of plasterboard (preferebaly the expensive dense 'soundbloc' type with dense mineral wool slabs above it). Not a cheap job by any means, and it will mean lowering the ceiling by about 100mm at a minimum (the bigger the gap the more effective it will be). Oh, and you can forget taking this opportunity to put downlights in the new ceiling. Any holes will just compromise the acoustic properties.
I probably explained too much about the solution not the problem there, but the issue with impact noise is the vibration and simply trying to stick foam on the underside of the slab will do nothing substantial to stop it. You need firstly to decouple the new celing from the existing one as much as you can and then provide a dense new layer to stop the sound coming through. It is that dense layer that stops the sound, not the mineral wool. The mineral wool serves to mostly stop noise echoing inside the cavity. you create.
I'm guessing that if the sound is intrusive through a concrete slad that your neighbours have cheap laminate flooring. It might be worth checking the rules for flooring in your building. Some leases and/or tenancy agreements ban the use of hard flooring outside kitchens and bathrooms unless there is an underlay to stop this sort of problem and it is often ignored. I'm not sure if you'd want to confront your neighbours on this sort of level, though.
To understand how is works. There are two components, impact/vibration (walking, dropping objects) and airborne (talking, TV etc.)
Impact: if you tap one spoon on another, they will both vibrate and ring. To stop the vibration, you can grip the second spoon tightly or put rubber/towel between them when you tap. With impact sound, you need to detach your secondary ceiling from the actual concrete ceiling or cover one side (ideally on top) with thick rubber to absorb the sound. like a car, low profile tires equal higher road noise.
Foam won't make any difference and neither will putting insulation between them. Hence, you need a properly done suspended ceiling below the concrete ceiling that has rubber mounts where they connect. Foam is used in studios to reduce echo, not to insulate the room from the outside.
Airborne: this is like sound from a radio, to quieten the radio, you can put it inside a closed box (the thicker the box the better it works) or cover it with think blankets, dense form or similar materials.
In practice, good Rockwool (not B&Q "soundproof" loft insulation) is placed between the layer. A rubber mat is placed between two 15mm or 18mm plasterboard (soundbloc is recommended as is is heavy - think about the thickness of the box in the example above).
- the rubber matt absorbs impact and dampens airborne sounds
- the two plasterboards absorb some impact/airborne (much less than a concrete ceiling) but it has to be physically separated
- the rockwool absorbs airborne and reduces echoing of the sound
In conclusion: I have done this to my flat in an old Victorian house. My neighbour below did the same to his flat. I have wood flooring sitting on thick rubber mats and good quality rockwool stuffed between the joist.
We both have double plaster board ceilings, only mine is suspended.
Result. Due to having 6 spotlights in my flat (big mistake), I can hear little impact noise and very little muffles from loud talking (no TV or normal level talking)
My neighbour below cut corners and did not put a suspended ceiling plus he has about 8 spot lights. He still hears every footstep (no suspended ceiling hence impact noise coming through) but he does not hear talking or TV due to insulation and rubber mats
My 2 pence: Get in s specialist company, take their advice, no downlights. It is expensive but worth it. Expect to spend 3-5k minimum if you have the ceiling height. It is cheaper than selling (5-7k in fees) and buying elsewhere (fees plus stamp duty) and still risk the same issue.
Don't bother calling up your local friendly builder to 'replicate' the above in order to save money, they will cut corners due to lack on knowledge