Guide to noise barriers
Noise barriers, or acoustic screens, are commonly used to reduce the effect of noise from roads, rail and industrial sources on residential properties. In particular, they are often required by local authorities to achieve recommended noise levels in external areas, including gardens and communal amenity spaces.
In order for noise barriers to be effective, they should achieve the following criteria:
- Barriers must be generally imperforate. Hit and miss fencing, slatted fencing or foliage are not effective noise barriers as sound passes through the gaps.
- Barriers should have a minimum mass of 10 kg/m2. Noise may pass through lighter weight materials.
For masses above 10kg/m2, the sound reduction provided by a noise barrier is unlikely to improve. The performance will be limited by sound diffraction over the top of the barrier. Therefore, a 10kg/m2 close-boarded timber fence will normally provide the same noise reduction as a 100mm concrete wall. Be careful if suppliers are recommending heavier noise barrier options for acoustic reasons, as these reasons may be false. Call us for an impartial view.
Set out below are common architectural screening options with comments on their acoustic effectiveness. It should be noted that, although some options will provide limited reduction in actual sound levels, any sort of visual screening has been shown to provide a subjective acoustic benefit – people are less bothered by a noise source that they cannot see!
Combinations of different barrier types are often also used for aesthetic or practical reasons. For example, an acoustic fence could be used on top of an earth bund where there was a requirement for a very high barrier (this is a particularly cost-effective option for sites where there is a lot of earth spoil which would otherwise have to be transported off site), or a green screen could be used in front of a brick wall for a more attractive aesthetic.
Cass Allen are experienced in the design and specification of noise barriers. Please let us know if you would like more information.