How to Measure Construction Noise Effectively
A practical guide to measuring noise levels using your smartphone and what the readings mean in the context of UK legal thresholds.
Documenting noise levels accurately can make your complaint far more credible. Here's how to do it properly.
What Unit is Noise Measured In?
Noise is measured in decibels (dB). The scale is logarithmic — meaning 80 dB is not twice as loud as 40 dB, it's many times louder.
UK Noise Thresholds for Construction
| Time | Typical Limit |
|---|---|
| Daytime (07:00–23:00) | 75 dB at site boundary |
| Night-time (23:00–07:00) | 45 dB |
These figures come from BS 5228:2009, the British Standard code of practice for noise and vibration control on construction and open sites.
Using Decibel X on Your Phone
The Decibel X app (available on iOS and Android) is widely regarded as one of the most accurate smartphone sound level meters. To get reliable readings:
- Hold your phone at arm's length, pointing towards the noise source
- Take readings over at least 30 seconds to capture a meaningful average
- Note the LAeq value — this is the equivalent continuous sound level and is what councils and courts typically refer to
- Screenshot or export the data with a timestamp
Tips for Reliable Evidence
- Record from multiple positions (inside your home, at your front door, at the garden boundary)
- Take readings on different days and at different times
- Note the weather — wind can affect readings
- Keep a written log alongside your measurements
What If Levels Are Below the Threshold?
Even if measured levels are below 75 dB, you may still have grounds to complain if the noise is a statutory nuisance under the Environmental Protection Act 1990 — this is a qualitative assessment, not purely numerical.