Acoustic Testing: When UK Projects Need It

"Do we actually need to test this, or can we just spec it well and move on?" It's one of the most common questions we get asked mid-project, and the honest answer is: it depends what you're building, not how confident anyone feels about the design.

When testing is a legal requirement, not a nice-to-have

For new-build dwellings with a separating wall or floor, shared with another dwelling or a commercial unit, pre-completion testing is required under Approved Document E unless the construction uses an approved Robust Details specification. There's no discretion here: it's a Building Regulations compliance step, checked before completion, and a failed test means remedial work on a building that's already largely finished.

What Robust Details changes

The Robust Details scheme, run by Robust Details Ltd, is a library of roughly 40 pre-approved wall constructions and 30 floor constructions that have already been proven through extensive laboratory and field testing to meet Part E. Build to one of these details correctly, using an approved contractor, and you're exempt from pre-completion testing on that element. It's a genuine shortcut, but only if the construction is followed exactly. Deviate from the detail and you lose the exemption.

Why UKAS accreditation actually matters

Approved Document E states that test bodies conducting field measurements should preferably hold UKAS accreditation, or a recognised European equivalent. In practice, building control bodies across England increasingly insist on it, and not every testing company holds it. UKAS accreditation means the lab and its methods have been independently assessed against ISO/IEC 17025, the international standard for testing competence. A test result from an unaccredited tester can be challenged by building control, which defeats the entire purpose of testing in the first place.

What the test actually measures

Testing happens after third fix, once the building is largely complete but before floor coverings go down, and it measures two separate things: airborne sound insulation (DnT,w + Ctr) and, for floors, impact sound insulation (L'nT,w). The results are checked against the specific figures required under Part E for that type of separation, new-build or conversion. Passing one measure doesn't guarantee passing the other, they're tested and assessed independently.

Beyond residential: when else testing gets specified

Testing isn't limited to Part E residential projects. NHS healthcare schemes often require post-completion verification against HTM 08-01's Noise Rating targets. School projects sometimes require confirmation testing against BB93's reverberation time and background noise limits, particularly on larger contracts where the client wants documented evidence rather than a designer's assurance. Commercial fit-outs pursuing WELL certification need documented sound mapping and, in some cases, post-occupancy verification.

Common questions

What happens if a pre-completion test fails? Remedial work is required on the failed element, followed by retesting, which is exactly why getting the acoustic design right before construction starts matters more than most other trades realise.

Can we self-certify instead of using an accredited tester? No. Building control requires the test to be carried out by a member of a UKAS-accredited body or an equivalent registered competent persons scheme, not by the contractor or design team.

Working out what your project needs

See our Acoustic Testing & Compliance service or book a free survey to find out whether your project falls under a testing requirement before you commit to a construction method.

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