Noise impact assessment
A noise impact assessment looks at noise affecting a site, or noise a new use would create, so the council can judge whether people will be disturbed. Councils ask for one when new homes are planned near busy roads, railways or businesses, or when a scheme adds a noise source such as plant, a heat pump or a commercial use near neighbours.
This guide covers the rules in England. See Wales, Scotland and Northern Ireland.
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Two kinds of assessment
New homes near noise
Measures existing noise from roads, railways, airports or businesses and shows how the new homes will be protected, for example with layout, glazing or ventilation.
A new noise source
Predicts noise from new plant, equipment or activity, such as air conditioning, a heat pump, a gym or a takeaway, and compares it with the existing background level at the nearest homes.
What the consultant does
- Visits the site and measures existing noise levels, often over a day or more, including at night if that matters
- Predicts the noise from the new development or the effect of existing noise on it
- Compares the results with the relevant British Standards and guidance the council uses
- Recommends measures such as acoustic glazing, barriers, plant enclosures or limits on opening hours
Not the same as sound insulation testing
A noise impact assessment is a planning report about noise outside and between a site and its neighbours. Sound insulation testing is a Building Regulations test, done at completion, of the walls and floors between homes. A flats scheme near a busy road may need both.
In Wales, Scotland and Northern Ireland
This guide describes the rules in England. Building regulations are devolved, so here is how noise impact assessment works in the rest of the UK.
Welsh councils also ask for noise assessments where noise is an issue, and Welsh planning policy sets out its own approach to noise. Check your council’s requirements.
Councils in Scotland ask for noise assessments in similar situations, under Scottish planning guidance on noise. Check your planning authority’s requirements.
Councils in Northern Ireland may ask for a noise assessment where noise is an issue. Check your council’s requirements.
Common questions
Does my extension need a noise impact assessment?
Almost never. They are asked for when new homes are planned in noisy places, or when a scheme adds a noise source near neighbours. Check your council’s validation list if you are unsure.
Do I need one for an air source heat pump?
Many heat pumps can be installed without a planning application, subject to conditions including on noise. If yours needs planning permission, or is close to a neighbour, the council may ask for a noise assessment. Check the current rules for your nation before you install.
How long does a noise survey take?
It depends on the site and what the council wants measured. Some surveys are a few hours; others run over several days to capture night-time and weekend levels.
How much does a noise impact assessment cost?
It depends on the length of the survey and how complex the site is. Consultants set their own prices, so compare quotes and check what each one includes.
What happens if noise levels are too high?
The consultant will usually recommend design changes, such as moving bedrooms away from a road, better glazing, a different ventilation system or an acoustic enclosure around plant. The council may make these planning conditions.
Is it the same as the sound test for flats?
No. Sound insulation testing checks walls and floors between homes for Building Regulations. A noise impact assessment is for planning and looks at noise from outside or from a new use.
New to the jargon? See our glossary of terms, from air permeability to TrustMark.