Most acoustic treatment budgets are set by guessing. A contractor quotes for "some ceiling panels," the client halves the budget during value engineering, and the project delivers a room that still echoes because the treatment area was insufficient to achieve the RT60 target. The cost estimator spreadsheet described here prevents this by working backwards from the acoustic target to the required treatment area, then pricing up the options.
The spreadsheet has four tabs: RT60 Target Calculation, Treatment Options, Cost Build-Up, and the Summary Budget. They are sequentially dependent — you must complete the Target Calculation before the Treatment Options, and both before the Cost Build-Up.
The Core Calculation: From RT60 Target to Treatment Area
Step 1: Determine your RT60 target
The target depends on the room type and applicable standard. Common targets for commercial spaces:
| Room Type | RT60 Target | Standard |
|---|---|---|
| Open-plan office | 0.4–0.6 s | ISO 3382-3, WELL v2 Feature 74 |
| Private office | 0.4–0.6 s | BS 8233:2014, ASHRAE 189.1 |
| Conference room (< 100 m³) | 0.4–0.5 s | BS 8233, ANSI S12.60 |
| Classroom | 0.4–0.6 s | ANSI S12.60, BB93 |
| Restaurant | 0.7–1.0 s | BS 8233 recommendation |
| Hotel lobby | 1.0–1.4 s | No standard, design guidance |
| Recording studio (control room) | 0.2–0.3 s | Industry practice |
| Concert hall (mid-frequency) | 1.8–2.2 s | ISO 3382-1 |
Enter the target at the top of the RT60 Target Calculation tab. The spreadsheet uses this as the basis for all subsequent calculations.
Step 2: Enter room dimensions
| Input | Value | Units |
|---|---|---|
| Length | 10.0 | m |
| Width | 8.0 | m |
| Height | 2.7 | m |
| Volume (auto) | 216 | m³ |
| Total surface (auto) | 264 | m² |
Step 3: Enter existing surface absorption
The tab includes an absorption table for the room's existing finishes. Enter each surface and its material — a dropdown linked to a 60-material library. The spreadsheet calculates existing total absorption A_existing at 500 Hz and 1000 Hz (the frequencies most relevant to speech intelligibility targets), and presents the average:
| Surface | Area (m²) | Material | NRC | A (m² sabins) |
|---|---|---|---|---|
| Concrete floor | 80 | Bare concrete | 0.02 | 1.6 |
| Plasterboard ceiling | 80 | Painted plasterboard | 0.05 | 4.0 |
| North wall | 27 | Painted concrete block | 0.07 | 1.9 |
| South wall (windows) | 27 | Glazing 10 mm | 0.10 | 2.7 |
| East wall | 21.6 | Painted plasterboard | 0.05 | 1.1 |
| West wall | 21.6 | Timber veneer panels | 0.07 | 1.5 |
| Fittings | — | — | — | 2.0 (estimate) |
| Total A_existing | — | — | — | 14.8 m² |
Step 4: Calculate additional absorption required
From Sabine: A_required = 0.161 × 216 / 0.50 = 69.6 m² (for RT60 target 0.50 s)
Additional absorption needed: 69.6 − 14.8 = 54.8 m²
This is the output of Tab 1 and the input to Tab 2.
Tab 2 — Treatment Options
Tab 2 presents four treatment categories, each with typical NRC performance and installed cost ranges. For each category, enter how much area you want to allocate, and the tab calculates the absorption contribution.
Category 1: Acoustic Ceiling Tiles (Suspended Grid)
Ceiling tiles in a concealed or exposed grid are the most cost-effective way to add large absorption areas. The NRC of commercial ceiling tiles ranges from 0.55 (budget mineral fibre) to 0.95 (high-performance fibreglass).
| Product Type | NRC | Installed Cost (US$/m²) | Installed Cost (AU$/m²) | Installed Cost (UK£/m²) |
|---|---|---|---|---|
| Budget mineral fibre, 600×600 | 0.55–0.65 | $18–25 | AU$22–30 | £15–22 |
| Mid-range mineral fibre | 0.70–0.80 | $25–35 | AU$30–42 | £20–28 |
| High-performance fibreglass | 0.85–0.95 | $35–45 | AU$42–55 | £28–38 |
| Perforated metal (with backing) | 0.70–0.85 | $55–85 | AU$66–100 | £45–70 |
For the worked example (54.8 m² additional absorption needed), installing 80 m² of high-performance ceiling tile (NRC 0.90) contributes 80 × 0.90 − 80 × 0.05 (replacing plasterboard) = 68.0 m² net additional absorption. This exceeds the target, so the ceiling tile alone solves the problem.
Category 2: Fabric-Wrapped Wall Panels
Wall panels are used when ceiling treatment is not sufficient (structural soffits, heritage ceilings) or when frequency-specific control is needed (thicker panels provide more low-frequency absorption).
| Panel Thickness | NRC | Freq Performance | Installed Cost (US$/m²) |
|---|---|---|---|
| 25 mm (standard) | 0.70–0.80 | Good mid/high, poor bass | $40–65 |
| 50 mm (standard) | 0.85–0.95 | Good mid/high, moderate bass | $55–85 |
| 75 mm (bass-extended) | 0.90–1.00 | Good across 250–4000 Hz | $70–110 |
| 100 mm (broadband) | 0.95–1.00 | Strong down to 125 Hz | $85–120 |
| Designer fabric-wrapped | 0.80–0.90 | Good mid/high | $90–160 |
Wall panels have one important installation consideration: effective area. A wall panel covers one side only, and panels must be spaced from reflective surfaces by at least their own thickness to work correctly. Panels installed flush against a hard wall can lose 20–30% of their rated absorption. The spreadsheet applies a 0.85 efficiency factor for wall panels unless you specify that they are spaced.
Category 3: Suspended Acoustic Baffles
Baffles hang vertically from the ceiling and present two absorptive faces to the room. Their effective area is approximately 1.7–2.0 times their physical area, making them highly efficient in rooms with difficult ceilings (exposed services, high bays, structural concrete).
| Baffle Type | NRC (per face) | Effective Area Multiplier | Installed Cost (US$/m² physical) |
|---|---|---|---|
| Standard fibreglass baffle 50 mm | 0.90 | 1.8 | $65–90 |
| Premium fibreglass baffle 75 mm | 0.95 | 1.9 | $85–120 |
| Fabric-wrapped baffle 50 mm | 0.85–0.90 | 1.7 | $80–110 |
| Printed acoustic baffle | 0.80–0.90 | 1.7 | $90–150 |
| Felt baffle (sustainable) | 0.75–0.85 | 1.6 | $70–100 |
Baffles at 40–60% ceiling coverage provide approximately the same acoustic effect as a full acoustic ceiling tile installation, at a higher per-m² cost but lower total cost because less physical area is used. They are the standard specification for warehouses, sports halls, and any room where a full suspended ceiling is architecturally unacceptable.
Category 4: Spray-Applied Acoustic Texture
Spray-applied systems (typically cellulose fibre or mineral wool compounds applied to structural soffits or walls) are the lowest-cost option for large areas with irregular geometry. They are not removable, are difficult to repair, and require surface preparation, but where budget is the primary constraint, they deliver reasonable NRC at low installed cost.
| System | NRC | Installed Cost (US$/m²) | Notes |
|---|---|---|---|
| Standard cellulose spray (12 mm) | 0.50–0.65 | $25–35 | Low cost, basic finish quality |
| Enhanced cellulose spray (25 mm) | 0.65–0.75 | $35–50 | Better NRC, paintable |
| Mineral wool spray (25 mm) | 0.70–0.80 | $40–60 | Fire-rated, used in car parks |
| Acoustic plaster systems | 0.60–0.75 | $55–90 | High aesthetic quality |
Spray systems underperform their rated NRC at low frequencies (below 250 Hz), making them unsuitable as the sole treatment in rooms with significant bass reverberation problems.
Tab 3 — Cost Build-Up
This tab combines the treatment areas selected in Tab 2 into a project budget. It follows the standard preliminaries + measured works format used in construction quantity surveying:
| Item | Area / Qty | Unit Rate | Total |
|---|---|---|---|
| Preliminaries | |||
| Site setup + protection | 1 | $1,500 | $1,500 |
| Acoustic measurement (pre) | 1 | $800 | $800 |
| Ceiling Treatment | |||
| Remove existing plasterboard ceiling tiles | 80 m² | $8/m² | $640 |
| Supply + install acoustic grid ceiling | 80 m² | $40/m² | $3,200 |
| Reinstate lighting (LED panels, re-fit) | 8 | $120/unit | $960 |
| Reinstate sprinkler heads (if present) | 12 | $85/unit | $1,020 |
| Wall Treatment | |||
| Supply + install wall panels 50 mm | 20 m² | $70/m² | $1,400 |
| Perimeter shadow gap (aluminium trim) | 30 lm | $12/lm | $360 |
| Commissioning | |||
| Acoustic measurement (post) | 1 | $800 | $800 |
| Compliance report | 1 | $500 | $500 |
| Subtotal (construction) | $11,180 | ||
| Design contingency (10%) | $1,118 | ||
| Total project budget | $12,298 |
Worked Example: 200 m³ Open-Plan Office
Room: 10 m × 8 m × 2.5 m, concrete soffit, vinyl tile floor, painted block walls, 25% glazing. 30 occupants.
Existing RT60 at 1000 Hz (calculated): 1.9 seconds
Target RT60: 0.5 seconds (ISO 3382-3 for open-plan office, speech intelligibility criterion)
Additional absorption required: (0.161 × 200 / 0.5) − (0.161 × 200 / 1.9) = 64.4 − 17.0 = 47.4 m²
Treatment Scenario A — Ceiling tiles only:
- 80 m² ceiling at NRC 0.85 (replacing bare concrete at 0.02): net contribution = 80 × (0.85 − 0.02) = 66.4 m²
- Exceeds target: post-treatment RT60 ≈ 0.38 s (slightly over-dampened)
- Cost: 80 m² × $35/m² installed = $2,800 (tiles only, no grid system change if suspended grid exists)
- 40 m² physical baffle area × 1.8 effective × NRC 0.90 = 64.8 m² effective absorption
- Post-treatment RT60 ≈ 0.40 s
- Cost: 40 m² × $80/m² = $3,200 (higher unit cost, but preserves ceiling access for services)
- 20 m² wall panels at NRC 0.90: 18.0 m² contribution
- 40 m² ceiling tiles (NRC 0.85): 33.2 m² contribution (replacing concrete)
- Total additional: 51.2 m² — slightly over target
- Post-treatment RT60 ≈ 0.44 s
- Cost: 20 m² × $65/m² + 40 m² × $35/m² = $1,300 + $1,400 = $2,700
What the Spreadsheet Does Not Include
Be transparent with clients about scope exclusions:
- HVAC noise reduction: If background noise exceeds the relevant limit (e.g., NC-35 for offices), ductwork lining or silencer specification is a separate package typically costing $5,000–20,000 depending on system complexity.
- Sound masking: Adding a sound masking system to improve speech privacy in an open-plan office costs $2–5/m² for a plenum-mounted system, separate from the absorption treatment budget.
- Structural isolation: If low-frequency flanking is a problem (mechanical plant, road traffic), structural isolation is a major works package beyond the scope of surface absorption treatment.
- Acoustic testing and certification: Post-treatment measurement for compliance certification should be budgeted separately at $600–1,500 per room depending on complexity.
Related Resources
- Acoustic Simulator — calculate required treatment area and predict post-treatment RT60 for any room
- Acoustic Design Cost-Benefit Analysis — ROI evidence for presenting the business case
- Acoustic Consultant Fees 2026 — what acoustic consultancy and specification services cost
- Acoustic Consultant Overspecification — how over-treatment wastes budget and degrades performance
- Acoustic Treatment Cost Calculator Guide — detailed cost breakdown methodology