Worked Example: Living Room — BS 8233 Residential Comfort
60 m³ living room with heavy carpet, upholstered furniture, and plasterboard walls
A 60 m³ residential living designed to BS-8233 requires RT60 ≤ 0.6s. With Painted plaster on the ceiling, the calculated RT60 is 0.5s — PASS.
Room Setup
Total surface area: 109.6 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| Ceiling | Painted plaster | 30.0 | 0.04 |
| Floor | Heavy carpet | 30.0 | 0.29 |
| Walls — plasterboard | Plasterboard on studs | 30.0 | 0.07 |
| Sofa + armchairs | Upholstered seating | 6.0 | 0.55 |
| Curtains | Curtains (medium weight) | 5.0 | 0.56 |
| Window | Double glazing 6mm | 4.0 | 0.03 |
| Chimney breast | Painted plaster | 3.0 | 0.04 |
| Door | Solid timber door | 1.6 | 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 = 6 × 5 × 2 = 60 m³
- 2
Total Surface Area
Stotal = 30.0 + 30.0 + 30.0 + 6.0 + 5.0 + 4.0 + 3.0 + 1.6 = 109.6 m²
- 3
Absorption per Surface at 500 Hz
Ceiling: 30.0 m² × 0.04 = 1.20 Sabins
Floor: 30.0 m² × 0.14 = 4.20 Sabins
Walls — plasterboard: 30.0 m² × 0.05 = 1.50 Sabins
Sofa + armchairs: 6.0 m² × 0.56 = 3.36 Sabins
Curtains: 5.0 m² × 0.49 = 2.45 Sabins
Window: 4.0 m² × 0.04 = 0.16 Sabins
Chimney breast: 3.0 m² × 0.04 = 0.12 Sabins
Door: 1.6 m² × 0.08 = 0.13 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 1.20 + 4.20 + 1.50 + 3.36 + 2.45 + 0.16 + 0.12 + 0.13 = 13.12 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 60 / 13.12 = 0.74s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 0.5s. Target: 0.4--0.6s per BS-8233. Verdict: PASS
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 11.9 | 9.6 | 13.1 | 22.0 | 29.1 | 30.6 |
| RT60 (s) | 0.81 | 1.01 | 0.74 | 0.44 | 0.33 | 0.32 |
| Target (s) | — | — | 0.60 | 0.60 | 0.60 | — |
| Verdict | — | — | FAIL | PASS | FAIL | — |
Compliance Verdict
Reference:
Open the AcousPlan calculator pre-loaded with the exact room dimensions (6m × 5m × 2m) and RT60 target (0.6s).
Open CalculatorField Story
A family in a 1930s semi-detached house in Leeds is renovating the front reception room, replacing the original suspended timber floor with underfloor heating beneath heavy wool carpet. The 6 m by 5 m room with original 2 m ceilings creates a compact 60 m³ volume where furnishings have significant acoustic impact. The three-seater sofa and two armchairs provide mid-frequency absorption equivalent to several acoustic panels. Full-length curtains across the bay window add useful absorption that disappears when opened — a natural variability matching room usage. Plasterboard walls over the original lath-and-plaster provide low-frequency panel absorption. BS 8233:2014 recommends RT60 below 0.6 s for living rooms to ensure comfortable television viewing and conversation.
Frequently Asked Questions
What RT60 does a Living Room — BS 8233 Residential Comfort achieve?
With the specified materials and dimensions (6m x 5m x 2m, volume 60m3), the calculated mid-frequency RT60 is 0.5s using the Sabine equation. The target under BS-8233 is 0.4--0.6s. The result is a PASS.
What materials are used in this residential acoustic example?
This example uses Painted plaster on the Ceiling (NRC 0.04), Heavy carpet on the Floor (NRC 0.29), Plasterboard on studs on the Walls — plasterboard (NRC 0.07), Upholstered seating on the Sofa + armchairs (NRC 0.55), Curtains (medium weight) on the Curtains (NRC 0.56), Double glazing 6mm on the Window (NRC 0.03), Painted plaster on the Chimney breast (NRC 0.04), Solid timber door on the Door (NRC 0.09). The total absorption at 500 Hz is 13.1 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.