Watch the full discussion:
Passing a sound test is one of the biggest hurdles in flat conversions and new-build developments—and one of the most misunderstood.
We recently sat down with an experienced acoustic consultant Jonathan Howell from Peninsular Acoustics. We had a long discussion about some regular talking points that come up with our clients. The conversation is predominantly around sound insulation testing and designing and building to meet the building regulations Part E, resistance to the passage of sound.
What is a sound test (and why does it matter)?
A sound test measures how much noise passes between properties under UK Building Regulations – Part E.
There are two key measurements:
- Airborne sound (DnT,w + Ctr) → voices, music, TV
- Impact sound (L’nT,w) → footsteps, chair movement
To pass:
-
Airborne must be high enough
- New build flats = 45 dB or More
- Conversions (e.g., houses to flats) = 43 dB or More
-
Impact must be low enough
- New Build Maximum = (62 dB or less)
- New Build Maximum = (64 dB or less)
If you're unfamiliar with the requirements, you can view a full breakdown here:
Part 'E' Building Regs Click Here
Book a consultation with our acoustic specialists Click Here
Why do sound tests fail?
🚫 1. Flanking sound (the biggest cause)
Sound doesn’t just travel through floors—it also moves:
- Around edges / down walls (Especially in lightweight blockwork as commonly seen in new builds)
- Through walls & air gaps
- Via structural junctions (RSJs, I Beams etc)
Even well-built floors can fail if flanking paths aren’t controlled.
🚫 2. Poor installation
- Gaps at perimeters
- Incorrect installation of acoustic layers
- Rigid fixings bridging the system
- Using the wrong depth screws
Small details have a big impact on results.
🚫 3. Treating products as solutions
A common mistake is relying on individual product claims:
“This underlay gives X dB reduction, so it will pass.”
Sound testing evaluates the entire construction, not a single component.
🚫 4. Timber floor constructions
Timber floors are more challenging because they:
- Transmit vibration more easily
- Have more flanking paths
- Lack mass compared to concrete
These require properly designed acoustic systems.
What actually helps you pass?
✅ Get the right Spec - Airborne sound is easier to treat than most think!
- Planning ahead in the design stage can save on costly rip outs and retrofits. A 'cheap' solution can cost more down the line, in money and time.
- Don't wing it, Design it! You risk failure when choosing a borderline specification.
- Don't scrimp on space! In most cases, the larger the void you create when developing an acoustic wall or ceiling system, the better it will perform (especially for low frequency noise)
Remember:
- Isolation: Resilient Bars, Clip & Channel, Acoustic Hangers, Independent Stud & Ceilings.
- Insulation: Rockwool RW45, Rockwool RW3, MaxiSlab, HushSlab or dB Slab infilled into the void, make sure not to compress too tight!
- Mass: dBoard, Maxiboard, Tecsound, Barrier Mat, Siniat, Knauf or Soundbloc plasterboard. Use multiple layers for the best results!
✅ Use a proven system
The most consistent advice from acoustic consultants is:
Use a build-up that has already been tested and proven in real conditions.
This gives:
- Predictable outcomes
- Reduced risk of failure
- Evidence if required
You can view examples of tested, compliant systems here:
dB Part E Systems Click Here
✅ Don't forget to focus on impact sound
Most common failures occur due to:
- Footfall noise
- Flanking paths
This is particularly important when installing hard floor finishes.
✅ Ensure correct installation
Key principles:
-
Maintain separation between elements
- Use Resilient Bars, Acoustic Hangers or an Independent Ceiling System
-
Avoid rigid connections
- Don't overtighten fixings through Resilient Bars - Top Tip ✓ Push to see if flexible or rigid.
-
Seal all perimeters, Prevent flanking noise
- Walls & Ceilings: Leave a 5mm expansion gap around your wall or ceiling system, infill this with acoustic sealant, along with any airgaps.
- Floors: This also applies for floor systems, we also supply Flanking Strip, dB Seal and Perimeter Strips to isolate your acoustic flooring system.
- Studs: Use dB Isolation Roll around your independent stud to isolate sound.
Even high-performance systems can fail if installed incorrectly.
Example of a Tested Floor System (dB Part E System 1)
A typical tested floor build-up in a residential conversion included:
- Engineered hardwood flooring
- Acoustic layer (dB Matting 15mm) tacked onto the subfloor
- Structural deck (18mm chipboard)
- Timber joists with mineral wool insulation (RW45 100mm Acoustic Slabs)
-
Resilient ceiling system:
- Maxi Res Bars, fixed to underside of joist using wood screws
- Siniat 15mm acoustic Plasterboard + Fireline 15mm Plasterboard, fixed to the Res Bars using Drywall Screws
- Scrim Taped and Plastered to finish.
- Perimeter sealed with Acoustic sealant.
Independent Test Results:
- Impact sound (L’nT,w): 49 dB
- Airborne sound (DnT,w + Ctr): up to 51 dB
What This Means
UK Building Regulations (Part E) require:
- Impact sound ≤ 62–64 dB
This system achieved:
- 49 dB, significantly outperforming the requirement
This demonstrates that well-designed floor systems can achieve high levels of acoustic performance, even in challenging constructions.
How This Compares to Typical Floor Finishes
Typical ranges:
| Floor Type | Typical Performance |
|---|---|
| Basic finishes | Higher impact levels |
| Soft floor systems | ~45–55 dB L’nT,w |
| Tested acoustic systems | ~45–50 dB L’nT,w |
The key takeaway:
Performance depends on the system—not just the surface finish.
What impact performance should you aim for?
- Minimum compliance: ≤ 62 dB
- Good performance: ≤ 55 dB
- High performance: ~45–50 dB
When it comes to impact - Lower values indicate better sound insulation.
Key Insight from the Expert
“It’s not about the individual product—it’s about how the entire construction performs as a system.”
Final Takeaway
Most sound test failures are avoidable.
Successful projects typically:
- Use tested and compliant systems
- Follow correct installation practices
- Address flanking sound paths early
If you’re planning a project, start with proven solutions:
Talk To An Expert
Speak to our team and find the right specification for your project.
📞 01928 571 856
📧 hello@soundinsulationstore.co.uk
Sound Test FAQs – Part E Building Regulations
What is a sound test in the UK?
A sound test (Part E Building Regulations) measures how much airborne and impact noise passes between separating floors and walls in residential buildings. It is required for new builds and most conversions such as flats.
What is the difference in sound testing between England, Scotland and Northern Ireland?
All UK nations require sound insulation testing for separating floors and walls, but the regulations and standards differ slightly:
England & Wales (Approved Document E)
Uses DnT,w + Ctr for airborne sound and L’nT,w for impact sound. Standard targets are typically 45 dB airborne and 62–64 dB impact.
Scotland (Section 5 – Noise)
Uses a different technical standard based on ISO measurements and Robust Construction details. The performance targets are generally similar but assessed under Scottish Building Standards rather than Part E.
Northern Ireland (Technical Booklet G)
Also uses airborne and impact sound performance standards, but with its own compliance guidance and testing framework aligned closely with UK ISO methodology.
In all regions, the principle is the same: prevent airborne sound transfer (voices, TV, music) and control impact sound (footsteps and vibration), but the exact documentation and compliance route differs.
How do you pass a sound test?
To pass a sound test you must use a fully designed acoustic system that controls mass, isolation and flanking noise paths. Correct installation and sealing of all junctions is essential to prevent sound leaks.
What are the required Part E sound test levels?
Airborne sound must achieve 45 dB or higher (43 dB for conversions). Impact sound must be 62 dB or lower. Both measurements must pass for compliance.
What is flanking noise?
Flanking noise is sound that travels around a structure rather than directly through it. It typically moves through walls, ceilings, floors, and structural junctions, and is one of the most common reasons for sound test failure.
What is sound bridging?
Sound bridging occurs when rigid materials create a direct path for vibration to travel between building elements. This bypasses acoustic insulation and significantly reduces soundproofing performance.
What is acoustic isolation?
Isolation is the separation of building elements so vibration cannot transfer through rigid connections. It is achieved using resilient bars, acoustic hangers, floating floors, and decoupled wall systems.
Why do sound tests fail?
Common causes include flanking noise, poor installation, sound bridging, air gaps, and relying on individual products instead of a tested system. Even small detailing errors can cause failure.
How do you acoustically treat electrical sockets?
Sockets can be a weak point for sound leakage. They should be treated using acoustic socket boxes (Click Here), made to maintain airtightness and reduce airborne sound transmission.
Do I need a sound test for a flat conversion?
Yes. Most residential conversions require pre-completion sound testing under Part E Building Regulations unless using approved Robust Details.
What is a good sound test result?
Good performance is typically around 45–50 dB impact and 50+ dB airborne. Minimum compliance is 62 dB or less for impact sound.
