Worked Example: Small Meeting Room — BS 8233 Acoustic Design
RT60 calculation for a 4-6 person meeting room under BS 8233:2014. The compact volume makes achieving low RT60 straightforward with standard acoustic ceiling tiles and carpet, though wall treatment improves clarity for video calls.
A 54 m³ meeting room designed to BS-8233 requires RT60 ≤ 0.6s. With Rockfon Sonar 25mm on the ceiling and Fabric-wrapped panel 50mm on walls, the calculated RT60 is 0.23s — PASS.
Room Setup
Total surface area: 93.4 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| ceiling | Rockfon Sonar 25mm | 20.0 | 0.85 |
| walls-main | Plasterboard on studs | 34.6 | 0.07 |
| walls-treatment | Fabric-wrapped panel 50mm | 14.0 | 0.80 |
| floor | Carpet (heavy) | 20.0 | 0.30 |
| windows | Double glazing 6mm | 3.0 | 0.04 |
| door | Solid timber door | 1.8 | 0.08 |
Absorption coefficients sourced from manufacturer datasheets and ISO 354 test reports. Browse the full acoustic materials database.
Step-by-Step Calculation
- 1
Room Volume
V = L × W × H = 5 × 4 × 2.7 = 54 m³
- 2
Total Surface Area
Stotal = 20.0 + 34.6 + 14.0 + 20.0 + 3.0 + 1.8 = 93.4 m²
- 3
Absorption per Surface at 500 Hz
ceiling: 20.0 m² × 0.82 = 16.40 Sabins
walls-main: 34.6 m² × 0.05 = 1.73 Sabins
walls-treatment: 14.0 m² × 0.78 = 10.92 Sabins
floor: 20.0 m² × 0.14 = 2.80 Sabins
windows: 3.0 m² × 0.04 = 0.12 Sabins
door: 1.8 m² × 0.08 = 0.14 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 16.40 + 1.73 + 10.92 + 2.80 + 0.12 + 0.14 = 32.11 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 54 / 32.11 = 0.27s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 0.23s. Target: ≤ 0.6s per BS-8233. Verdict: PASS
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 19.2 | 26.4 | 32.1 | 39.3 | 44.8 | 45.2 |
| RT60 (s) | 0.45 | 0.33 | 0.27 | 0.22 | 0.19 | 0.19 |
| Target (s) | — | — | 0.60 | 0.60 | 0.60 | — |
| Verdict | — | — | PASS | PASS | PASS | — |
Compliance Verdict
Reference: BS 8233:2014 Table 4
BS 8233 recommends RT60 ≤ 0.6s for meeting rooms. Small rooms are easier to treat but flutter echoes between parallel walls require attention. Fabric wall panels on at least one wall pair prevent flutter.
STI result: 0.79 (per IEC 60268-16:2020)
Cost Estimate
Costs are indicative and vary by region, supplier, and installation complexity. For a detailed cost breakdown, use the AcousPlan calculator.
Open the AcousPlan calculator pre-loaded with the exact room dimensions (5m × 4m × 2.7m) and RT60 target (0.6s).
Open CalculatorField Story
A financial services firm reports that their new glass-walled meeting rooms suffer from terrible acoustics during video calls. Remote participants complain about echo and the room picks up conversation from adjacent desks. The 20 m² rooms have glass walls on two sides, plasterboard on two sides, a hard ceiling, and no carpet. Flutter echoes between parallel glass surfaces make the room almost unusable. The fit-out contractor installs acoustic ceiling tiles, carpet, and fabric panels on the plasterboard walls, dramatically improving call quality within a single weekend installation.
Frequently Asked Questions
What RT60 does a Small Meeting Room — BS 8233 Acoustic Design achieve?
With the specified materials and dimensions (5m x 4m x 2.7m, volume 54m3), the calculated mid-frequency RT60 is 0.23s using the Sabine equation. The target under BS-8233 is 0.6s or less. The result is a PASS.
What materials are used in this office acoustic example?
This example uses Rockfon Sonar 25mm on the ceiling (NRC 0.85), Plasterboard on studs on the walls-main (NRC 0.07), Fabric-wrapped panel 50mm on the walls-treatment (NRC 0.8), Carpet (heavy) on the floor (NRC 0.3), Double glazing 6mm on the windows (NRC 0.04), Solid timber door on the door (NRC 0.08). The total absorption at 500 Hz is 32.1 Sabins.
How much does acoustic treatment cost for this room?
The estimated treatment cost is £2,592 for 54 m2 of absorptive material at approximately £48/m2. Actual costs vary by region, supplier, and installation complexity.
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All calculations are advisory and based on the Sabine equation (ISO 3382-2:2008 Annex A). Results require professional verification for compliance submissions. Absorption coefficients are sourced from manufacturer datasheets and ISO 354 test reports.