Guide to Sound Testing in London
Introduction to Sound Testing in London
When constructing or converting residential buildings in London, one crucial but often overlooked aspect is sound insulation. Ensuring your property meets the necessary acoustic standards isn’t just a courtesy to future occupants—it’s a legal requirement.
Under Building Regulations Approved Document Part E, developers are required to demonstrate that separating walls and floors between dwellings provide adequate resistance to the passage of sound. Whether you’re constructing a new apartment block, converting a house into flats, or repurposing a commercial space into residential use, sound testing plays a vital role in ensuring compliance and creating comfortable living environments.
So, what does sound testing involve, and what types should you expect during your project in London? Let’s dive into the details.
Why Is Sound Testing Important?
Sound testing is designed to assess the effectiveness of acoustic insulation between dwellings. The goal is to ensure a reasonable level of sound separation—so that people can enjoy peace and privacy in their own homes without being disturbed by their neighbours.
In London, with its dense housing stock and increasing number of mixed-use developments, proper sound insulation is more important than ever. This is especially critical in buildings where different households share walls or floors.
When Is Sound Testing Required?
If your project involves:
- A new-build dwelling
- A conversion into self-contained flats
- A material change of use (e.g., turning an office into residential units)
…and the dwellings are attached via a shared wall or floor that is not used exclusively by the same occupants, then sound testing is mandatory before completion.
According to the regulations, at least 10% of each type of separating wall or floor construction must be tested.
The Two Main Types of Sound Testing
Sound testing typically falls into two categories: Airborne Sound Testing and Impact Sound Testing. Depending on your building’s layout and construction, both may be required.
1. Airborne Sound Testing
Airborne sound testing measures how well walls or floors prevent sound from traveling through the air—such as talking, TV noise, or music.
This test is commonly carried out between adjacent rooms in separate dwellings—like bedrooms or living rooms—both horizontally (side by side) and vertically (floor to ceiling).
How It Works:
A loudspeaker is placed in the “source” room and generates high sound levels. The sound levels are then measured in both the source and adjoining “receiver” room using a calibrated microphone. Background noise levels and the reverberation time (how long sound lingers) are also recorded to ensure accuracy.
What’s the Requirement?
- New build: Minimum of 45 dB airborne sound insulation
- Conversions: Minimum of 43 dB
The higher the decibel value, the better the sound insulation.
2. Impact Sound Testing
Impact sound testing is relevant for vertically-separated dwellings—for example, between an upstairs flat and a downstairs unit. This test assesses the level of noise generated by impacts (think footsteps, dropped items) on the floor.
How It Works:
A tapping machine is placed on the floor in the upper room. This device drops small hammers in a controlled sequence to simulate footfall. Sound levels are then measured in the room below. Like with airborne testing, reverberation and background levels are also taken into account.
What’s the Requirement?
- New build: No more than 62 dB
- Conversions: No more than 64 dB
In this case, the lower the decibel value, the better the insulation performance.
Sample Sound Testing During Conversions
If you’re converting an existing building—such as turning an old office into flats—it’s wise to carry out sample sound testing before you start construction.
Why? Because many older buildings weren’t designed with acoustic separation in mind. You might find:
- Insufficient mass in the separating structure
- Poor isolation between walls/floors
- Unintended sound paths (known as flanking transmission)
Common Flanking Paths
One of the most frequent culprits is the inner leaf of an external cavity wall—particularly if it’s built using lightweight blocks like Thermalite. Sound can travel along these paths and reduce overall insulation performance, even if the separating wall or floor is well-built.
By doing a pre-construction sample test, you’ll get an accurate picture of the current sound insulation and can plan a targeted acoustic upgrade—potentially saving time and costly remedial works later on.
Sound Testing of External Facades
Another area of acoustic performance often overlooked is the external facade. This is particularly relevant for properties located in noisy areas—like those near busy roads, railways, or flight paths.
How It Works:
- A loudspeaker is placed approximately 5 meters outside the building at a 45-degree angle.
- Sound pressure levels are measured 2 meters in front of the facade and 1.5 meters above ground.
- The results help evaluate how much environmental noise enters through the external envelope of the building.
This type of testing is essential for developers targeting high-performance builds or for residential units located in designated noise-sensitive zones.
Professional, Accredited Testing Services
Sound testing must be performed by qualified professionals using high-precision equipment. At APT Sound Testing, our engineers use Class 1 Norsonic instruments — the gold standard in acoustic testing.
We carry out testing to UKAS-accredited and ISO-compliant standards, ensuring results you (and your building inspector) can trust. Whether you need testing for a small conversion or a large residential scheme, our team has the experience to guide you through every step.
Get in Touch
If you’re working on a building project in London and need sound testing to comply with Part E of the Building Regulations, we’re here to help. From pre-construction advice to final handover testing, APT Sound Testing provides a complete acoustic consultancy service.
📞 Call us on 01525 303905
🌐 Visit: APT Sound Testing Services