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Sound proofing

Ivor the Engine

Established Member
Just started looking into sound proofing for the ceiling in my basement conversion which will be an AV room. Have looked at a company called Custom Audio Designs who suggest 100mm mineral wool.

I'll probably put in some sort of floating ceiling to add to the proofing.

Does anyone have any good experiences they would like to share on this?


Established Member
Mr Engine, essentially you have 2 potential problems with sound proofing and you need to assess what type of soundproofing problem you have. This is not too difficult to do and will save you money and time in the long run. Easiest way is to put a loudspeaker in the cellar and crank it up with a bass heavy track, use a typical sound level which you expect to use. Go upstairs and listen to what you can hear, if its bass you have some structure borne issues. If you can here treble then you have an air borne issue. This is hugely simplified, but gives a start.

Air borne issues will be resolved with what you have suggested, some mass from the plasterboard and rockwool, just make sure use plenty of sealant to make sure you get no flanking paths (short circuits such as a pipe going though a hole etc).

The bass issue is more difficult to resolve and mass is what you need, several layers of plasterboard, even the heavy types should be considered. If you have a big issue then barrier foam can also be fitted between joists and false ceiling, this is a 95kg/m3 foam so you going to have issues holding it up. The final problem with structure borne noise is that and solution you use should ideally float, not easy to achieve!

Hope this gives you some ideas, but try the experiment and go from their.


Ivor the Engine

Established Member
Thanks for the ideas. Just removed the ceiling which means you can hear a pin drop from upstairs. Either way, when the ceiling was up, you could still hear every damn word.

I'll give your advice a go and re-post

The recommendation I got from Acoustic Solutions was to put mineral wool in the cavity space before fixing resilient bars to the joists; adding two additional layers of 12.5mm plasterboard (or thicker) to resilient bars with an acoustic membrane in between; then filling the gap around the ceiling and walls with non-hardening flexible mastic.

Anyone got any thoughts on this?


Established Member
Sounds sensible way forward, that method will improve air and structure borne noise, but its performance is very dependent on how well installed. IE. no flanking paths....



Established Member
adding two additional layers of 12.5mm plasterboard (or thicker) to resilient bars with an acoustic membrane in between

I can recommend fibreboard to put in between your plasterboard sheets, although it's quite rubbery and a bugger to cut.

I've just pulled down part of a wall of a 70's recording studio built for very, VERY loud rock'n'roll and their idea to seperate rooms was a brick wall then a 10" air gap, then 2 layers of very thick roofing felt (!) behind a stud wall followed by dense rockwool and then hessian over that to finish. Maybe a dated idea by today's standards but it seemed to work for them.


Distinguished Member
Hi Ivor

if you ring sheffield insulation found on the net, they will tell you exactly what to use, I would suggest acoustic fibre board as elootos says but then use acoustic plaster board as well to cover it and form a new ceiling. We have just done this method in a downstairs cloakroom which ajoins the dining room (in other words you don`t want to hear anyone using the loo whilst having your dinner) and the results are amazing. We used double boards as a precaution and its like being in a sealed soundproof room.

just thought I`d thrown in my twopenneth


PS. 2400X1200 12.5MM acoustic boards were £4.65 each as against £3.50 for ordinary boards so not a lot more really


Established Member
Flanking path is simply a secondary path the noise takes which your soundproofing fails to address. An example may be improving a wall soundproofing then finding that noise travels over the top through the roof space. Or something less obvious like electrical conduit between rooms allowing noise to pass though.



increase the mass of the plasterboard assemblies with visco-elastic materials like greenglue, they will lower the resonance point without losing as much space, there is an excellent article on extra layers of plasterboard vs damping here: http://www.greengluecompany.com/greenGlue-vs-ExtraDrywall.php

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