Where Can I Start the Building Line Due to Noise?
This is a common question we get when sites are being looked at for residential development, often before purchase and before planning submission. The factors governing this are the average noise levels both day and night, the maximum noise levels during the night and the allowed noise levels at the residential properties. There are British Standards and other guidance that provide the required noise criteria for residential properties, including specific areas such as bedrooms, living rooms and private gardens. Some Planning Authorities also have Supplementary Planning Guidance that provided additional and often more restrictive requirements.
The required setbacks are also dependent upon a number of factors:
- the layout of the development site, including the topography of the site, (relating to the traffic sources)
- the orientation and massing of houses, (as noise will travel around structures and penetrate deeper into the site)
- the boundary treatment for the site but also the specific properties, (such as earth bunds and fencing)
- the internal layout of the houses, (such as placing habitable spaced such as bedrooms away from the most exposed facades).
The assessment will normally consider the potential impacts with windows left partly open and this is also often a requirement to avoid overheating and developments where windows are required to be closed and or have higher than normal acoustic performance, local authorities have been known to refuse permission, so it is essential that a detailed consultation is undertaken prior to any specific recommendations can be provided.
It is now required that development consider the noise impacts based upon the principles of sustainable development before additional measures are used such as specific acoustic mitigation including, barriers, glazing and ventilation.
Due to the large number of variables the specific setbacks from the site boundary to the property boundary will vary and can be significant. For smaller, quieter roads the distances may be as low as 5 metres, increasing to tens of metres for busy A & B roads and up to hundreds of metres for motorways and dual carriageways.
Where sites are designated for housing as part of the local plan or there is a specific housing need, there is the potential to request a relaxation of the specific assessment criteria of up 5 dB for internal levels and even higher for gardens.
AAC can undertake detailed noise assessment for any scale of residential development in any environment and will always try to provide the best advice and guidance based upon the available information.