Worked Example: Trading Floor — Hard Flooring Acoustic Failure
RT60 calculation for a financial trading floor where vinyl flooring (required for cable management) and extensive glazing prevent achieving the 0.5s open plan target despite significant ceiling treatment.
A 1800 m³ open plan office designed to BS-8233 requires RT60 ≤ 0.5s. With Rockfon Sonar 25mm on the ceiling, the calculated RT60 is 0.56s — FAIL.
Room Setup
Total surface area: 1497.2 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| ceiling | Rockfon Sonar 25mm | 550.0 | 0.85 |
| walls-main | Plasterboard on studs | 260.0 | 0.07 |
| floor | Vinyl/linoleum floor | 600.0 | 0.03 |
| windows | Double glazing 6mm | 80.0 | 0.04 |
| door | Solid timber door | 7.2 | 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 = 30 × 20 × 3 = 1800 m³
- 2
Total Surface Area
Stotal = 550.0 + 260.0 + 600.0 + 80.0 + 7.2 = 1497.2 m²
- 3
Absorption per Surface at 500 Hz
ceiling: 550.0 m² × 0.82 = 451.00 Sabins
walls-main: 260.0 m² × 0.05 = 13.00 Sabins
floor: 600.0 m² × 0.03 = 18.00 Sabins
windows: 80.0 m² × 0.04 = 3.20 Sabins
door: 7.2 m² × 0.08 = 0.58 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 451.00 + 13.00 + 18.00 + 3.20 + 0.58 = 485.78 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 1800 / 485.78 = 0.60s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 0.56s. Target: ≤ 0.5s per BS-8233. Verdict: FAIL
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 265.4 | 406.2 | 485.8 | 543.4 | 528.4 | 523.1 |
| RT60 (s) | 1.09 | 0.71 | 0.60 | 0.53 | 0.55 | 0.55 |
| Target (s) | — | — | 0.50 | 0.50 | 0.50 | — |
| Verdict | — | — | FAIL | MARGINAL | MARGINAL | — |
Compliance Verdict
Reference: BS 8233:2014 Table 4
Large open plan floors with hard flooring are extremely difficult to treat. The 600 m² vinyl floor reflects nearly all incident sound. Even with extensive ceiling treatment, additional measures (desk screens, sound masking) are essential.
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 (30m × 20m × 3m) and RT60 target (0.5s).
Open CalculatorField Story
A City of London investment bank's trading floor requires raised access flooring with vinyl finish for the hundreds of data cables running to each trading desk. The IT department vetoes carpet tiles because spilled coffee could damage floor-box connectors. With 600 m² of hard vinyl floor, even near-complete Rockfon ceiling coverage cannot bring the RT60 below target. The ambient noise during trading hours is measured at 72 dBA — comparable to standing next to a busy road. Traders develop a habit of shouting across desks rather than using internal phones. The acoustic consultant recommends desk-mounted screens with absorptive faces and a zone-based sound masking system to manage the acoustic environment electronically.
Frequently Asked Questions
What RT60 does a Trading Floor — Hard Flooring Acoustic Failure achieve?
With the specified materials and dimensions (30m x 20m x 3m, volume 1800m3), the calculated mid-frequency RT60 is 0.56s using the Sabine equation. The target under BS-8233 is 0.5s or less. The result is a FAIL.
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), Vinyl/linoleum floor on the floor (NRC 0.03), 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 485.8 Sabins.
How much does acoustic treatment cost for this room?
The estimated treatment cost is £30,250 for 550 m2 of absorptive material at approximately £55/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.