Worked Example: Restaurant Dining Room — BS 8233 Acoustic Design
400 m³ restaurant with acoustic plaster ceiling, timber floor, and exposed brick
A 400 m³ restaurant designed to BS-8233 requires RT60 ≤ 0.8s. With Acoustic plaster 15mm on the ceiling and Curtains (medium weight) on walls, the calculated RT60 is 0.62s — PASS.
Room Setup
Total surface area: 520.0 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| Ceiling — acoustic plaster | Acoustic plaster 15mm | 70.0 | 0.66 |
| Ceiling — painted plaster | Painted plaster | 130.0 | 0.04 |
| Floor | Timber floor (sealed) | 200.0 | 0.09 |
| Walls — brick | Brick (unglazed) | 60.0 | 0.04 |
| Walls — curtains | Curtains (medium weight) | 16.0 | 0.56 |
| Seating (60 covers) | Upholstered seating | 16.0 | 0.55 |
| Banquette panels | Fabric-wrapped panel 50mm | 8.0 | 0.78 |
| Window | Double glazing 6mm | 16.0 | 0.03 |
| Doors | Solid timber door | 4.0 | 0.09 |
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 = 20 × 10 × 2 = 400 m³
- 2
Total Surface Area
Stotal = 70.0 + 130.0 + 200.0 + 60.0 + 16.0 + 16.0 + 8.0 + 16.0 + 4.0 = 520.0 m²
- 3
Absorption per Surface at 500 Hz
Ceiling — acoustic plaster: 70.0 m² × 0.65 = 45.50 Sabins
Ceiling — painted plaster: 130.0 m² × 0.04 = 5.20 Sabins
Floor: 200.0 m² × 0.10 = 20.00 Sabins
Walls — brick: 60.0 m² × 0.03 = 1.80 Sabins
Walls — curtains: 16.0 m² × 0.49 = 7.84 Sabins
Seating (60 covers): 16.0 m² × 0.56 = 8.96 Sabins
Banquette panels: 8.0 m² × 0.78 = 6.24 Sabins
Window: 16.0 m² × 0.04 = 0.64 Sabins
Doors: 4.0 m² × 0.08 = 0.32 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 45.50 + 5.20 + 20.00 + 1.80 + 7.84 + 8.96 + 6.24 + 0.64 + 0.32 = 96.50 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 400 / 96.50 = 0.67s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 0.62s. Target: 0.6--0.8s per BS-8233. Verdict: PASS
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 48.4 | 67.8 | 96.5 | 109.2 | 109.8 | 103.7 |
| RT60 (s) | 1.33 | 0.95 | 0.67 | 0.59 | 0.59 | 0.62 |
| Target (s) | — | — | 0.80 | 0.80 | 0.80 | — |
| Verdict | — | — | PASS | MARGINAL | MARGINAL | — |
Compliance Verdict
Reference:
Open the AcousPlan calculator pre-loaded with the exact room dimensions (20m × 10m × 2m) and RT60 target (0.8s).
Open CalculatorField Story
A contemporary brasserie in Manchester occupies a converted Victorian warehouse with exposed brick walls and sealed timber floors — surfaces the interior designer refuses to conceal. The acoustic consultant specified 15 mm acoustic plaster on half the ceiling, maintaining the raw industrial aesthetic while delivering significant mid-frequency absorption. The remaining ceiling is painted plaster over the open kitchen area where extraction ductwork precludes treatment. Medium-weight linen curtains across the window bays provide variable absorption that can be drawn back during quieter lunch services. The 60-cover dining room features upholstered banquettes with fabric-wrapped backing panels absorbing speech frequencies at seated ear height. BS 8233:2014 recommends RT60 below 0.8 s for restaurants, preventing the Lombard spiral that plagues fashionable dining rooms where hard surfaces amplify conversation noise.
Frequently Asked Questions
What RT60 does a Restaurant Dining Room — BS 8233 Acoustic Design achieve?
With the specified materials and dimensions (20m x 10m x 2m, volume 400m3), the calculated mid-frequency RT60 is 0.62s using the Sabine equation. The target under BS-8233 is 0.6--0.8s. The result is a PASS.
What materials are used in this hospitality acoustic example?
This example uses Acoustic plaster 15mm on the Ceiling — acoustic plaster (NRC 0.66), Painted plaster on the Ceiling — painted plaster (NRC 0.04), Timber floor (sealed) on the Floor (NRC 0.09), Brick (unglazed) on the Walls — brick (NRC 0.04), Curtains (medium weight) on the Walls — curtains (NRC 0.56), Upholstered seating on the Seating (60 covers) (NRC 0.55), Fabric-wrapped panel 50mm on the Banquette panels (NRC 0.78), Double glazing 6mm on the Window (NRC 0.03), Solid timber door on the Doors (NRC 0.09). The total absorption at 500 Hz is 96.5 Sabins.
How much does acoustic treatment cost for this room?
Cost data is not available for this example. Use the AcousPlan calculator to estimate treatment costs for your specific room configuration.
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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.