What Is Sound Insulation Testing? A Part E Guide
Sound insulation testing, often called pre-completion testing or Part E testing, checks that the walls and floors between homes stop enough noise passing from one to the next. If you are building new flats or houses that share a wall, or converting a building into homes, Building Control will usually need passing test results before they sign the work off.
In this guide
What Part E requires
Part E of the Building Regulations deals with resistance to the passage of sound. The part that drives testing is requirement E1: separating walls and floors between dwellings, and between rooms for residential purposes such as student rooms or care home bedrooms, must give a reasonable level of sound insulation. Approved Document E explains how to show you have met it, and pre-completion testing is the standard way.
Part E also covers internal walls and floors within a home and the common parts of blocks of flats, but those are dealt with through the design and specification rather than on-site testing.
Which projects need testing
- New build flats with separating walls and floors.
- New build semi-detached and terraced houses with separating walls.
- Conversions that create new homes, such as a house split into flats or an office or barn converted to residential. Conversions must be tested.
- Rooms for residential purposes, for example in student accommodation, hostels and some care settings.
Detached houses with no shared walls or floors do not need sound testing.
Robust Details: the alternative for new builds
For new build homes only, you can avoid testing by building the separating walls and floors to an approved Robust Detail and registering each plot with Robust Details Ltd before work starts on it. The construction then has to be built exactly as the detail shows. This route is not available for conversions, and if a plot is not registered in time or the detail is not followed, you are back to testing.
We arrange pre-completion sound testing for new build and conversion projects, and can look at your separating wall and floor details before you build.
What the tests involve
There are two kinds of test:
- Airborne sound, such as voices and televisions. A loudspeaker plays a loud noise in one room and the level is measured in the room next door or below. Walls and floors are tested.
- Impact sound, such as footsteps. A tapping machine is run on the floor above and the noise is measured in the room below. Only floors are tested.
Testing is done on a sample rather than every home. Approved Document E sets out how many sets of tests are needed, based on the number of homes and the different types of separating construction on the site. Your Building Control body will confirm the number for your project.
For new build homes, Approved Document E expects separating walls and floors to achieve at least 45 dB for airborne sound (DnT,w + Ctr) and floors to achieve no more than 62 dB for impact sound (L’nT,w). For homes formed by a conversion the standards are 43 dB and 64 dB. Different figures apply to rooms for residential purposes. Approved Document E also expects the testing body to hold suitable accreditation, such as UKAS accreditation or ANC registration.
Getting ready for test day
Testing happens near the end of the build. The rooms being tested need to be essentially finished, with:
- Windows and external doors fitted and closed, and internal doors hung.
- Walls and ceilings complete, including skirting, sockets and service penetrations sealed.
- Power available, and access to both rooms in each pair at the same time.
- A quiet site, with no noisy trades working nearby during the tests.
If the site is not ready, the tester may not be able to complete the tests, which costs you time.
How to avoid a failed test
Most failures come from small details rather than the main wall or floor build-up. Common causes include:
- Gaps around joists, beams or service pipes passing through separating construction.
- Back-to-back sockets or switches in separating walls.
- Missing or poorly fitted resilient layers, so the floor finish touches the walls.
- Flanking sound through the outer walls, floor voids or ceiling voids.
Getting the details right on the drawings and checking them on site before they are covered up is far cheaper than fixing them later. If a test fails, the cause has to be found and put right and the test repeated, and Building Control may ask for more tests across the site.
Sound insulation testing is From £375 + VAT. Guide price. Get a free quote for your project. See how much Sound Insulation Testing costs and how many tests your site is likely to need.
Frequently asked questions
Do house conversions need Sound Testing?
Yes, if the conversion creates new homes, such as flats. Robust Details cannot be used for conversions, so testing is the normal way to show the separating walls and floors comply.
When should I book Sound Testing?
Plan it early and book it for when the relevant rooms are finished, near the end of the build. Leave time before handover in case any remedial work and retesting is needed.
What happens if my sound test fails?
The cause needs to be investigated and fixed, and the test repeated until it passes. Building Control may also ask for additional tests on other plots.
Do I need Sound Testing for a detached house?
No. Sound testing applies where walls or floors separate one home from another, so a detached house with no shared walls or floors does not need it.
Get a Free Quote for Your Project
We arrange pre-completion sound testing for new build and conversion projects, and can look at your separating wall and floor details before you build.
Last reviewed: November 2026. General guidance for England only. Get project-specific advice before relying on it.