Friday 30 May 2014 1.38pm
The advice above is spot on
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