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Improving sound insulation in homes Many people are bothered by neighbour noise. The problem can occur in any type of attached house, flat or bungalow but most commonly in flats that have been converted from large houses. You may be bothered by your neighbour’s noise because: · you are unusually sensitive to noise · your neighbour behaves unreasonably · the sound insulation between your homes is poor While everybody sometimes hears some noise such as raised voices, laughter or occasional loud music, you should not be able to hear your neighbour’s normal conversation or television. You can look for a legal or DIY solution to the problem. This document outlines some of the DIY measures possible. First of all you have to decide how the sound is travelling into your home. It may be coming directly through the party wall or floor or it may be coming along another route called a flanking path. The most common such path is the inner leaf of an external cavity wall. Some examples of flanking paths are shown in Figure 1. Figure 1. Transmission paths for airborne sound through rooms in a pair of flats separated by a timber floor It is essential to determine the path of the sound so that the remedial treatment can be chosen correctly. Some information on how to diagnose the sound path is contained in leaflet XL41 . The unwanted noise travelling along direct and flanking paths makes the structure vibrate and this causes the sound to radiate into your room. A solution is to build another wall or ceiling beside the original, but not connected to it. In flats converted before June 1992 there may have been little or no sound insulation improvement undertaken on the floor. If this is the case, upgrading the floor is almost certain to be effective. Remedial Treatment: Walls The following steps for construction are suggested, see Figure 2: · build a studwork frame, attached to the ceiling and floor but not fixed to the original wall · hang mineral wool inside the cavity, and tack between the studs or to a batten on the wall · line the studwork with two layers of plasterboard, making sure the joints between the sheets in the first and second layer do not coincide · seal perimeter and all other sound paths with flexible sealant Figure 2. Wall improvement layout of studwork and plasterboard Remedial Treatment: Ceilings The principle equally applies to ceilings, the idea is to build a new ceiling below the existing one. The following steps for construction are suggested, see Figure 3: · attach wall plates to the walls to give the shortest room span and run new ceiling joists between them · fix mineral wool between the new ceiling joists, or drape it over them · line with two plasterboard layers, making sure the joints between the sheets in the first and second layer do not coincide · seal perimeter and all other sound paths with flexible sealant Figure 3. Independent ceiling layout Remedial Treatment: Floors A floating floor in the room above can be constructed as an alternative to an independent ceiling providing that the joists can carry the increased dead loads satisfactorily. The following steps are suggested, see Figure 4: · remove original floor and skirting boards and insert glass fibre or rock wool quilt between the joists. · refit the floor boarding and lay 25mm of glass fibre or rock wool (for this layer a density between 60 and 80 kg/m3 is required) and cover with 19mm plasterboard, laid loose with a gap at the perimeter walls. · glue, not nail, tongue and grooved chipboard not less than 18mm thick, leaving perimeter gap of 10mm. · seal perimeter and all other sound paths with flexible sealant This method will raise the floor by about 65mm so adjustments to doors, stairs and other fittings may need to be taken into account. Figure 4. Floating floor improvement layout A more in-depth description of the above three methods and other information can be found in DIGEST 2932. It is recommended that you read this publication before starting any building work. It is often found that problems with airborne and structure borne sound are associated both with direct transmission through a floor and flanking transmission down supporting walls and other associated structures. It is essential to establish if your problem is due to direct transmission, flanking transmission or a combination of both. Providing the sound is mainly entering your home through a direct path then the correct use of the constructions explained above should reduce it substantially. However, there is always a risk that the treatment of a wall or floor alone will not be sufficient. A more thorough acoustic investigation may be necessary before the appropriate remedial measures can be decided upon. Footnote: walls, floors and ceilings A number of manufacturers are now producing a range of systems designed to improve sound insulation in homes. Information on the likely sound insulation performance should be requested. You are advised to consider carefully the information supplied by the manufacturer before adopting this type of remedy. Specific publications referred to in this leaflet are: 1. Leaflet XL4 Improving sound insulation in your home 2. Digest 293 Improving sound insulation of separating walls and floors Available from CRC, details below Construction Research Communications Ltd publishes for BRE. Details of our range of publications on sound insulation and other building matters can be obtained from CRC. Telephone 020 7505 6622. Or see the website at www.bre.co.uk

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