What is tested?
Airborne tests assess sound transmitted through separating walls or floors, such as speech or music. Impact tests assess transmission through a separating floor from an impact source. The methods and results are different, so a single informal “noise reading” is not a substitute for the required assessment. [2]
Approved Document E gives these performance values for dwellings formed by material change of use:
- Airborne insulation through separating walls and floors: at least 43dB, expressed as DnT,w + Ctr.
- Impact transmission through separating floors: no more than 64dB, expressed as L'nT,w. [2]
Higher is better for the airborne value; lower is better for the impact value. The notation matters when comparing a report with the standard. These conversion figures should not be confused with the different values for newly erected homes. [2]
Testing does not replace acoustic design
A conversion floor may need several coordinated measures rather than simply insulation between joists. Review the floor finish, mass, resilient layers, ceiling and connections to surrounding walls. Gaps and service penetrations can undermine the assembly, while flanking transmission can bypass it. [2]
Ask the acoustic designer to identify which details are critical before work is covered. A practical drawing review should focus on junctions, pipe routes and interruptions to the separating construction, where a generic section may not explain what the contractor must do. [2]
Coordinate those details with fire separation. A proposed acoustic lining or service opening must also fit the building's fire strategy; the sound and fire specifications should not contradict each other. [3] [2]
How many tests are needed?
Approved Document E groups dwellings by their construction and uses a sampling approach. The number and location of tests depend on the separating walls and floors and the relevant groups or subgroups. A small conversion is not automatically exempt because it creates only a few flats. [2]
Agree the test plan before assuming that one test covers every floor or construction type. Provide the tester with the layout and construction information so the sample reflects what is actually being built. [2]
Can a product certificate replace testing?
No generic product certificate proves the performance of the finished building. Regulation 41 contains an alternative route involving approved robust details for the erection of new dwellings; it is not a blanket route around testing for material-change-of-use conversions. [1]
What happens after the test?
Retain the report identifying the tested locations, construction and results. If performance is inadequate, investigate the cause, agree remedial work and undertake the necessary further testing. Do not rely on a verbal assurance that a failed result is “close enough”. [2]
Arrange the testing alongside the completion process, not after the flats have been treated as fully finished and handed over. The results are part of the evidence supporting building-regulations compliance. [1] [4]