Understanding BS EN 1793: What Specifiers Need to Know

BS EN 1793 defines how to measure and declare the acoustic performance of road-traffic noise-reducing devices. Reading DLα and DLR correctly lets you compare systems on a like-for-like basis, right-size specifications, and streamline approvals.

Reading time: ~6 min Published: 12 Nov 2025 Theme: Specifiers’ guide
8 dB
DLα
Sound absorption (BS EN 1793-1)
28–29 dB
DLR
Airborne sound insulation (BS EN 1793-2)
Up to 40 years
Design life
Long-term service life reduces replacement cycles
Quick-slot
Cassette system
Fast, modular installation with minimal trimming and waste

Overview

BS EN 1793 defines how the acoustic performance of road-traffic noise-reducing devices is measured and declared. For specifiers, reading DLα (absorption) and DLR (airborne insulation) correctly enables like-for-like comparisons, avoids over- or under-specification, and makes planning and UKCA submissions more straightforward alongside BS EN 14388 and BS EN 1794. Using the published values to match barrier face type (reflective vs absorptive), height and span to the site context helps meet noise thresholds first time while limiting materials and rework. Meanwhile, Air’s Quick-slot cassette system and up to 40-year design life support predictable delivery and lower lifetime impact across highways, rail and utilities.

Why BS EN 1793 matters for specification

Planning and procurement rely on credible, comparable acoustic data. The BS EN 1793 series defines how absorption (DLα) and airborne insulation (DLR) are measured and declared for road-traffic noise-reducing devices. Understanding these metrics lets specifiers compare systems on a like-for-like basis, right-size height and face type, and evidence compliance alongside BS EN 14388 (product) and BS EN 1794 (non-acoustic performance).

Key idea: Use DLα and DLR to select reflective vs absorptive faces and the minimum viable height that satisfies the noise target, achieving compliance without oversizing.

Clarity & Comparability

Like-for-like product evaluation

1793 sets a common yardstick for absorption and insulation. Published DLα/DLR values let you compare systems fairly and select the most appropriate build-up.

Planning certainty

Right-sized, first-time compliance

Align specs to modelled receiver conditions to avoid rework. 1793 results support planning submissions and UKCA documentation with transparent evidence.

Design efficiency

Avoid overspecification

Using the minimum DLα/DLR that meets the target limits material use and installation complexity while maintaining performance and compliance.

What BS EN 1793 covers and how testing works

The 1793 series defines how to measure and report a barrier’s acoustic performance. For specifiers, the essentials are: DLα from EN 1793-1 (sound absorption) and DLR from EN 1793-2 (airborne sound insulation). Optional in-situ checks via EN 1793-5/-6 may be requested for project verification. Use these results with BS EN 14388 (product) and BS EN 1794 (non-acoustic performance) to complete UKCA submissions.

Laboratory transmission and reverberation suite used for EN 1793 testing
Figure. Accredited laboratory set-up: reverberation room for EN 1793-1 (DLα) and source/receiving rooms for EN 1793-2 (DLR).
  • EN 1793-1 (DLα): absorption measured in a reverberation room; higher values indicate more absorptive faces.
  • EN 1793-2 (DLR): airborne insulation measured in a transmission suite; higher values indicate greater sound blocking.
  • EN 1793-5/-6: optional in-situ acoustic verification under direct sound field after installation.
  • Documentation chain: pair 1793 results with EN 14388 (product) and EN 1794 (non-acoustic) for UKCA.
sound-icon

How it’s measured

DLα: reverberation room method (random-incidence absorption). DLR: source/receiving suites with calibrated microphones; results weighted to a traffic spectrum.

Interpretation tips

Use DLα for choosing reflective vs absorptive faces; use DLR to right-size height and build-up. Aim for the minimum that satisfies the modelled receptor targets.

Documentation

• EN 1793-1 / EN 1793-2 test reports • Product assessment / UKCA declaration • EN 14388 + EN 1794 references • Specifier guidance (DLα/DLR usage)

Reading the numbers: DLα (absorption) and DLR (airborne insulation)

BS EN 1793 provides two core single-number ratings used in specifications and approvals: DLα from EN 1793-1 (how much sound the surface absorbs), and DLR from EN 1793-2 (how much sound is blocked from passing through the barrier). Higher values indicate stronger performance in the respective property.

Interpretation tip: Use DLα to decide reflective vs absorptive faces in contexts with facing receivers or hard reflections. Use DLR to right-size overall barrier build-up/height to meet modelled receiver limits without overspecification.
Project verification: Lab results (EN 1793-1/-2) are product benchmarks under controlled conditions. Where required, on-site checks can be undertaken using EN 1793-5/-6 after installation.
Metric What it indicates Typical bands used in practice
DLα (dB) — EN 1793-1 Surface absorption 0–4 = low · 5–7 = medium · 8+ = high
DLR (dB) — EN 1793-2 Through-transmission insulation ~25–29 = B3 · >30 = B4 (heavier specialist builds)
Air (reference) Verified ratings DLα = 8 dB · DLR = 28–29 dB

Use these published values alongside BS EN 14388 (product standard) and BS EN 1794 (non-acoustic performance) to evidence compliance in UKCA submissions.

Compliance and UKCA marking

To be placed on the UK market, acoustic barrier systems must demonstrate conformity to BS EN 14388, the harmonised product standard for road-traffic noise-reducing devices. This framework references verified acoustic results from BS EN 1793-1 / 1793-2 and the non-acoustic mechanical and safety characteristics defined in BS EN 1794-1 / 1794-2. Together, these form the evidence base for UKCA declarations of performance.

Test data and verification

Independent laboratory tests carried out by the University of Salford confirm: DLα = 8 dB (EN 1793-1:2017) and DLR = 28–29 dB (EN 1793-2:2012). These results are referenced in BSI Verification Report 30249272 supporting EN 14388 compliance.

Full standard chain

EN 14388 → EN 1793 → EN 1794 creates a continuous compliance route: acoustic performance, structural integrity, durability, and safety. Including all referenced tests in tender documentation ensures a transparent audit trail for planners and clients.

Planning and specification support

Providing verified DLα/DLR values and UKCA documentation simplifies planning submissions, avoids conservative over-design, and gives authorities clear, comparable data. Access current certification and declarations in our Resources section.

Why early engagement helps specifiers

Understanding BS EN 1793 classifications early in the design process allows teams to integrate acoustic performance into project planning — rather than treat it as a late-stage compliance task. Early coordination ensures that the correct DLα and DLR classes are selected, physical constraints are accounted for, and the specification remains cost- and carbon-efficient.

coordination-icon

Coordinate acoustic design with layout

Identify where absorptive vs reflective faces are required based on geometry and receiver proximity - reducing retrofits later.

Right-size specifications

Apply verified DLα/DLR values to match planning conditions, avoiding unnecessary material use and simplifying UKCA documentation.

evidence-icon

Provide clear evidence

Include EN 1793 test reports, UKCA declarations and specification notes in tender submissions to streamline planning approvals.

Air: verified data at a glance

Independently tested acoustic performance with a documented compliance route for UKCA.

DLα = 8 dB EN 1793-1 · Absorption
DLR = 28–29 dB EN 1793-2 · Airborne insulation
Up to 40 years Design life
UKCA ready EN 14388 route
Property Standard Result Classification Test body
Sound absorption (DLα) BS EN 1793-1:2017 8 dB High (project-dependent class) University of Salford (UKAS)
Airborne sound insulation (DLR) BS EN 1793-2:2012 28–29 dB B3 University of Salford (UKAS)
Product assessment / UKCA route BS EN 14388 (product) + EN 1794 (non-acoustic) Verified — BSI verification

Full documentation available in the Resources section: EN 1793-1 / EN 1793-2 test reports, BSI verification summary for EN 14388 compliance, and UKCA Declaration. On-site verification (EN 1793-5/-6) can be provided where required by project.

FAQs

Quick answers on BS EN 1793 (DLα/DLR), how to apply the results in design, and the documents planners expect. For project-specific support, contact our technical team.

How do I decide between an absorptive and a reflective face?
Use an absorptive face where reflections could impact receivers (e.g., opposite façades, enclosed cuttings). Use reflective faces where redirected energy won’t create nuisance. Check your model and apply verified DLα/DLR to right-size height and build-up.
What do the single-number ratings actually mean?
DLα (EN 1793-1) rates surface absorption (higher = more absorptive). DLR (EN 1793-2) rates airborne insulation through the barrier (higher = more blocking). Typical bands: DLα 0–4 low, 5–7 medium, 8+ high; DLR ~25–29 = B3, >30 = B4.
Do on-site results need to match the lab values?
Lab values (EN 1793-1/-2) are product benchmarks in controlled conditions. Where required, on-site checks can be done using EN 1793-5/-6 after installation; geometry, height and interfaces will influence in-situ performance.
How do I use DLα/DLR to pass planning without overspecification?
Start from the modelled receiver targets, then choose the minimum DLα/DLR that meets those limits for the given geometry. Select face type, height and returns accordingly to avoid unnecessary materials.
What documents do planners typically ask for?
Product datasheet, EN 1793-1/-2 test reports (DLα/DLR), references to EN 14388 (product) and EN 1794 (non-acoustic), and the UKCA declaration. See our Resources tray.
What are Air’s verified acoustic ratings?
Air is independently tested to DLα = 8 dB (EN 1793-1:2017) and DLR = 28–29 dB (EN 1793-2:2012). Use these values to set face type and height in your scheme.
How does EN 14388 and EN 1794 relate to EN 1793?
EN 14388 is the product standard referenced for UKCA. It calls up EN 1793 for acoustics (DLα/DLR) and EN 1794 for non-acoustic performance (e.g., mechanical, durability). Together they form the compliance chain.
When is in-situ verification (EN 1793-5/-6) appropriate?
Where authorities request field confirmation or where complex geometry may affect results. We can support on-site verification plans once installation and access are agreed.
Does installation quality affect acoustic performance?
Yes. Consistent post spacing, tight interfaces and correct cassette seating reduce acoustic leakage. Poor tolerances can depress in-situ performance even if lab values are high.
Can you help align posts/spans and access with the acoustic spec?
Yes — we provide coordination notes covering face type, height, returns, posts/spans and access so the build matches the model and the declared DLα/DLR are realised on site.

In summary

BS EN 1793 gives specifiers a clear way to compare and document acoustic performance. Read DLα for absorption and DLR for airborne insulation, then right size the barrier to the modelled receiver targets. Pair these results with EN 14388 and EN 1794 to complete the UKCA evidence. Supporting resources are available in the resources tray.

Ready to apply BS EN 1793 in your spec

Download the product datasheet and open the resources tray for certificates and planning documents.

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