Worked Example: Executive Boardroom — WELL F74 Premium Finish
RT60 calculation for a premium boardroom using acoustic plaster instead of ceiling tiles for a high-end aesthetic. Demonstrates how WELL v2 Feature 74 compliance is achieved while maintaining the design quality expected in executive spaces.
A 180 m³ meeting room designed to WELL-F74 requires RT60 ≤ 0.6s. With Acoustic plaster 15mm on the ceiling and Fabric-wrapped panel 50mm on walls, the calculated RT60 is 0.31s — PASS.
Room Setup
Total surface area: 231.6 m². Calculation method: Sabine equation (ISO 3382-2:2008 Annex A).
Surface Materials
| Surface | Material | Area (m²) | NRC |
|---|---|---|---|
| ceiling | Acoustic plaster 15mm | 60.0 | 0.70 |
| walls-main | Painted plaster | 66.0 | 0.04 |
| walls-treatment | Fabric-wrapped panel 50mm | 30.0 | 0.80 |
| floor | Carpet (heavy) | 60.0 | 0.30 |
| windows | Double glazing 6mm | 12.0 | 0.04 |
| door | Solid timber door | 3.6 | 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 = 10 × 6 × 3 = 180 m³
- 2
Total Surface Area
Stotal = 60.0 + 66.0 + 30.0 + 60.0 + 12.0 + 3.6 = 231.6 m²
- 3
Absorption per Surface at 500 Hz
ceiling: 60.0 m² × 0.65 = 39.00 Sabins
walls-main: 66.0 m² × 0.04 = 2.64 Sabins
walls-treatment: 30.0 m² × 0.78 = 23.40 Sabins
floor: 60.0 m² × 0.14 = 8.40 Sabins
windows: 12.0 m² × 0.04 = 0.48 Sabins
door: 3.6 m² × 0.08 = 0.29 Sabins
- 4
Total Absorption at 500 Hz
Atotal = 39.00 + 2.64 + 23.40 + 8.40 + 0.48 + 0.29 = 74.21 Sabins
- 5
Sabine RT60 at 500 Hz
RT60 = 0.161 × V / A = 0.161 × 180 / 74.21 = 0.39s
- 6
Compare to Target
Mid-frequency RT60 (avg of 500, 1k, 2k Hz) = 0.31s. Target: ≤ 0.6s per WELL-F74. Verdict: PASS
Octave Band Results
| Frequency | 125Hz | 250Hz | 500Hz | 1kHz | 2kHz | 4kHz |
|---|---|---|---|---|---|---|
| Total Absorption (Sabins) | 14.7 | 44.9 | 74.2 | 99.7 | 117.8 | 113.3 |
| RT60 (s) | 1.98 | 0.65 | 0.39 | 0.29 | 0.25 | 0.26 |
| Target (s) | — | — | 0.60 | 0.60 | 0.60 | — |
| Verdict | — | — | PASS | PASS | PASS | — |
Compliance Verdict
Reference: WELL v2 Feature 74, L07
WELL Feature 74 requires RT60 ≤ 0.6s for enclosed meeting rooms. Acoustic plaster provides a seamless, premium ceiling finish that satisfies both acoustic and aesthetic requirements for executive spaces.
STI result: 0.76 (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 (10m × 6m × 3m) and RT60 target (0.6s).
Open CalculatorField Story
A law firm's managing partner insists that the new boardroom must look like a five-star hotel lounge — no visible ceiling tiles or acoustic panels. The interior designer presents a scheme with marble floors, plaster ceiling, and timber-panelled walls. The acoustic consultant explains this would produce an RT60 of 1.5 seconds, making conference calls with international clients impossible. The compromise: acoustic plaster sprayed directly onto the ceiling soffit (invisible but absorptive), fabric panels hidden behind decorative wall cladding, and heavy carpet. The WELL assessor confirms Feature 74 compliance at final inspection.
Frequently Asked Questions
What RT60 does a Executive Boardroom — WELL F74 Premium Finish achieve?
With the specified materials and dimensions (10m x 6m x 3m, volume 180m3), the calculated mid-frequency RT60 is 0.31s using the Sabine equation. The target under WELL-F74 is 0.6s or less. The result is a PASS.
What materials are used in this office acoustic example?
This example uses Acoustic plaster 15mm on the ceiling (NRC 0.7), Painted plaster on the walls-main (NRC 0.04), 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 74.2 Sabins.
How much does acoustic treatment cost for this room?
The estimated treatment cost is $12,750 for 150 m2 of absorptive material at approximately $85/m2. Actual costs vary by region, supplier, and installation complexity.
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Explore More
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.