BS 8233 sets the internal noise levels new homes should achieve. If you are applying for planning permission for dwellings on a site near a road, railway or commercial use, this is the standard your noise assessment will be judged against.
If that is what you need, our Residential Development Noise Assessment starts at $1,145 and includes the glazing and ventilation specification your architect needs.
The numbers
| Space | Period | Guideline level |
|---|---|---|
| Living rooms | Daytime, 07:00–23:00 | 35 dB LAeq,16h |
| Dining rooms | Daytime | 40 dB LAeq,16h |
| Bedrooms | Daytime | 35 dB LAeq,16h |
| Bedrooms | Night, 23:00–07:00 | 30 dB LAeq,8h |
Alongside these, WHO guidance on individual noise events leads most authorities to look for bedroom maximum levels around 45 dB LAFmax not being regularly exceeded at night. External amenity space — gardens and balconies — is generally looked at against a guideline of 50–55 dB LAeq,16h.
What the standard is not
BS 8233 gives guideline values, not legal limits. It also explicitly allows for reasonable judgement where a site cannot meet them, which is why the assessment matters as much as the numbers: a well-argued report on a difficult site can succeed where a mechanical comparison fails.
How ProPG fits in
In England, ProPG: Planning & Noise is the companion guidance most officers expect alongside BS 8233. It asks for an initial site noise risk assessment — negligible, low, medium or high — based on the external noise levels, and then for a proportionate response. A high-risk site is not automatically refused; it requires a stronger justification and better mitigation.
The part your architect actually uses
Meeting internal levels comes down to two specifications:
- Glazing. The acoustic performance each window must achieve, per facade. Not all facades need the same, and over-specifying every window is an expensive mistake.
- Ventilation. If windows must stay shut to meet the levels, the scheme needs a ventilation strategy that works with them closed — acoustic trickle vents, mechanical ventilation or MVHR — each with its own acoustic performance requirement.
An assessment that gives internal levels but no glazing and ventilation specification has done half the job. Neither part depends on a site visit, which is why this report works well desk-based.
Where the input data comes from
Either a measured survey, or published sources: strategic noise mapping, traffic flow data, rail timetables and speeds. Published sources are legitimate and widely accepted for many sites, and our reports always state which was used and what that means for confidence. Where an authority has specifically required measured data, you supply it or commission it locally — and we say so before you order.
Agent of Change
If your site is near an existing music venue, pub or industrial use, the Agent of Change principle applies: as the incoming development, the responsibility for mitigation is yours. Expect the authority to ask how you have protected your future residents from an existing, lawful noise source.
Why assessments get rejected
- Night-time maximum levels not assessed for bedrooms
- Ventilation ignored, so the glazing specification is unachievable in practice
- External amenity space not considered
- A single facade assessed and applied to the whole scheme
- No ProPG risk categorisation where the authority expects one
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