Reference

Glossary of construction noise and Section 61 terms

Section 61 · Updated

In short

These are the terms used in Section 61 applications and BS 5228-1 noise predictions, in plain words. Where an entry comes from the Act, it names the section. Where it describes a choice the platform makes, it is marked as the platform's guidance.

Terms

ABC method
One of the example methods in Annex E of BS 5228-1, the annex that gives examples of ways to judge noise effects. It sets a threshold for the noise from the site, using Table E.1, which gives example thresholds at dwellings. The threshold depends on how noisy the area already is: Category A for the quietest areas and Category C for the noisiest. Read more
Ambient noise
The noise already at a place before the works start. Read more
Best practicable means (BPM)
The Act's test for the steps taken to minimise noise. “Practicable” means reasonably practicable, having regard among other things to local conditions and circumstances, the current state of technical knowledge and the financial implications (section 72(2)). Read more
Facade and free-field levelsPlatform guidance
A free-field level is the level in the open, with no reflecting surface close by. A facade level is the level at the outside face of a building, which includes sound the building reflects. BS 5228-1 adds 3 decibels to a free-field prediction where the point of interest is 1 metre from the front of a building. The platform's predictions in an application are free-field: they add no facade reflection correction. Read more
LA90
The A-weighted level that is exceeded for 90% of the measurement time. It is often called the background level.
LAeq
The average noise level over a stated time, written LAeq,T where T is that time. It is the main figure used for construction noise, and an integrating sound level meter measures it. The A means the level is weighted to roughly follow how people hear. The eq means equivalent continuous: the steady level with the same sound energy as the real, changing noise over the same time. The ABC thresholds are written in decibels LAeq,T.
LAFmax
The highest level reached during a measurement, taken with the A-weighting and the fast time weighting. It is the loudest moment, not an average.
On-time
The share of the working period that a machine actually runs. A breaker used for 3 hours of a 10-hour day has an on-time of 30%. Read more
Period
A part of the week that BS 5228-1 assesses on its own, each with its own threshold: daytime, evenings and weekends, and night. The clock times are in the standard (Annex E, Table E.1).
Receptor
A place near the works that the noise could affect, such as a home, a school or an office. The platform predicts a level at each one.
Section 60 notice
A notice a council serves on the person carrying out, or going to carry out, works, setting requirements for how they are done (sections 60(2) and (5)). Read more
Sound power level
The noise a machine gives out, whatever the distance, in decibels. It is the starting figure for the standard's sound power method of prediction. BS 5228-1 Annex C gives typical levels for many types of plant as the level 10 metres away, and adding 28 decibels to one of those gives the sound power level. Read more
Threshold
In the ABC method, the level of noise from the works above which a potential significant effect is indicated, for a place in a given category and period. Read more

Related guides

Start an application

The Section 61 platform prepares an application and the evidence behind it. You check it and send it to your council yourself. Start an application.

Sources

The legislation cited was read on legislation.gov.uk on 26 October 2026.

This is guidance, not legal advice. Check with the council.