Sound vs Thermal Insulation

[purplemonkey]

hi, I'm looking to put Sound insulation in the joist area between ground and 1st floor. Knauf Sound insulation is generally harder to find then Thermal insulation, and I'm wondering is there any difference? I only have 50mm of space to place the insulation into, and I'm thinking what if I just cram 100 or 200mm thermal insulation into this gap? Would that work, or is it going to behave the same as thermal insulation i.e. it requires full expansion to operate?

I can't find any information on Knauf's website as to what the sound insulation properties of there thermal wool is, and I'm thinking this may be because its simply the same product, but they want to re badge and sale as different?

cheers to anybody providing 'sound' advice.

 

[Blagard]

There are essentially two ways sound goes through structures.

Via structure and/or Air. If your floor and ceiling are typical construction there is not going to be a lot you can do about sound carried through the structure except soft furnishing on the floor above like carpets.

Filling voids with thermal insulation types of material will help deaden sound carried by air but not as well as materials that have better sound absorbing properties. Your thermal insulation used for sound does not require expansion to work, so cramming 100 into a 50mm space will probably work better than say 50mm insulation laid loose. I think you will find that the Accoustic rolls by Knauf are made with the mineral wool fibres packed tighter

You would get better performance from materials designed specifically to deaden sound carried by air.

 

[purplemonkey]

nice one, thanks for the detailed reply
We have engineered wood floor floating on top of 5mm foam, then chipboard screwed to beams. we are installing plasterboard halfway down these beams in the room below so will just add 100mm insulation in a 50mm space and see what the result turns out like.

thanks