Can we Blow Sound Insulation into the Cavity Wall?


We are in the middle of a build and have put a steel beam into shared walls and discovered that the cavity between ourselves and our terraced neighbour is completely empty. Is there anything we can have blown in that's not too expensive to provide sound insulation? Thanks very much

Sue Watson


Hello Sue

Always a difficult one trying to deal with unknowns that crop up half way through a project.

Your only option to fill the entire cavity, is to use a blown fibre insulation. But beware this is not a DIY job, and must be carried out by a specialist installer. The installation of this material (which is very akin to mineral wool loft insulation that you can buy anywhere) will have a limited effect upon reducing sound transmittance.

To reduce sound transfer effectively requires the use of material that have high density over an appreciable thickness e.g. 100mm of masonry, whilst quite dense, is not quite thick enough to reduce sound transfer effectively - it may take up to 200mm thickness to do this. However, it is often possible to reduce sound by using a sandwich construction of differing density materials across a shorter distance. So if you were to line your wall with a metal, or timber frame that is spaced away from the wall face (no physical contact whatsoever) fill the species between the frame members using mineral wool insulation then clad the frame on the kitchen side using a combination of plywood / chipboard (this performs two roles of a dense panel, and gives a fixing for fitting your kitchen units) then face with a 'Soundbloc' plasterboard and you walls finishes - (tiles here would be a good addition too) this should absorb sound quite well.

The important thing is that the frame must not be fixed to the wall to are trying to stop the sound transferring through. Just fix around the perimeter to the flanking walls, floor and ceiling. The down side is that this will take a little space off your kitchen.

There is no easy answer to this one, and if you want an effective solution it will inevitably eat into your budget.
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