How do we go about soundproofing a fifty year-old semi detached?

July 2013

Question

Any advice on soundproofing a fifty-year-old semi-detached house? Noise from our neighbours such as doors banging, creaking floorboards and raised voices is particularly annoying in the bedroom. Due to the cost we are considering only soundproofing the main bedroom. Is it worthwhile to soundproof one room or is it only effective when the entire adjoining side of the house is treated? Any advice on other issues or good companies to use? Are there standards companies should meet?

Answer

Sound transfer between two properties can be a very annoying problem. Since the introduction of building regulations in 1992, there are clearly defined standards of sound insulation that need to be achieved in party-wall construction, and it is not at all uncommon to find problems in the sound insulation standard with older properties.

Noise can transfer from one property to another either by airborne, eg voices, television etc, or by impact, eg banging on walls or floors.

If you live in an older house and are unfortunate to have a noisy neighbour, then this can be a significant source of nuisance for you. I note that you describe issues of both the airborne and impact type. The good news is that it is possible to address these issues, particularly the airborne type.

The remedial works will be dependant on the specific nature of the construction. The chances are that much of the sound is penetrating through large holes or gaps in the wall. It is not uncommon with older properties to have holes or gaps in walls adjacent to where floor joists are supported on the party walls.

Accordingly, you need to check to see what direction the floor joists are spanning. The floor joists will be perpendicular to the floor boards. If the joists are spanning into the party wall, you should have a few floorboards lifted in order to establish how they are supported and to determine whether or not there are any gaps or holes adjacent to these. Any holes or gaps should be suitably infilled and sealed with a dense mortar mix. This can be done on a room by room basis and you will note a marked improvement by taking action of this nature.

Another potentially weak point is at the party wall or roof junction in the attic. There are often large gaps here and these should all be checked and infilled and sealed, not only for sound but also for fire proofing reasons as well. These simple measures can significantly improve the situation.

However if the wall is relatively thin or of lightweight construction, then you will need to look at upgrading the sound insulation standard to the wall in general, and the only practical way to do this is to line the internal face of the wall with a sound insulating material such as a rockwool sound insulation or a sound resisting plasterboard layer. Whereas it would obviously be preferable to have this done to the entirety of a wall, works of this nature do lend themselves to a room-by-room approach, and you will notice an improvement within a particular room after the works have been done. This is often a sensible approach which can be done on a phased basis when doing up the house room by room.

Works of this nature are not particularly complex and can be done by most registered builders.

Val O’Brien is a member of the building surveying professional group of the SCSI