Calculator
Sample results table
| Scenario | Budget | Duration | Risk index | Category | Recommended contingency | Recommended schedule buffer |
|---|---|---|---|---|---|---|
| Retail refresh, clear drawings, off-hours work | USD 45,000 | 6 weeks | 22.0 | Low | 7.1% | 6.0% |
| Apartment retrofit, partial occupancy, moderate utilities | USD 120,000 | 12 weeks | 49.5 | Moderate | 14.7% | 15.3% |
| Older facility, hazmat suspected, structural alterations | USD 380,000 | 26 weeks | 78.2 | Critical | 28.9% | 28.3% |
How the score is calculated
Each factor is rated from 1 (low risk) to 5 (very high risk). The calculator applies a weight to each factor and computes a weighted score.
Cost contingency and schedule buffer are then estimated using a smooth curve that grows faster at higher risk. This avoids overreacting to small risk differences on simpler renovations.
- Recommended contingency: 5% to 35%, scaled from the risk index.
- Recommended buffer: 3% to 40% of planned duration, scaled from the risk index.
Using this calculator effectively
- Enter project basics like budget and planned duration.
- Select a profile that matches your delivery approach.
- Rate each factor from 1 to 5 using evidence.
- Calculate and review top drivers and mitigations.
- Adjust buffers and re-run for alternative scenarios.
- Download the CSV or PDF for sharing and records.
Risk index interpretation
Each factor is rated 1 to 5, then normalized to a 0–100 risk index. Scores below 25 indicate predictable work with routine controls. A 25–49 range suggests moderate change potential, where tighter reviews reduce drift. A 50–74 score signals high exposure to rework, delays, and claims. Above 75, treat the project as uncertainty-heavy and validate assumptions early.
Weighting reflects uncertainty
Not every risk behaves the same in renovations, so the calculator applies weights to emphasize drivers that commonly trigger surprises. Structural changes and scope clarity are weighted higher because design gaps and hidden conditions can cascade into multiple trades. Hazard likelihood is weighted strongly because abatement can halt progress and increase costs. Profiles adjust weights slightly to match conservative or fast-track approaches without changing the 1–5 scale.
Contingency and buffer guidance
The tool converts the index into recommended cost contingency and schedule buffer using a curve. Lower scores produce single‑digit contingency, while higher scores push reserves toward the mid‑twenties. This helps avoid underfunding discovery work. Schedule buffer is expressed as a percentage of planned weeks, translating risk into float for approvals, procurement, and re-sequencing when conditions differ from drawings.
Driver-based mitigation planning
Results highlight top risk drivers by comparing each weighted rating to the project’s weighted average. Focus mitigation on those drivers first because they move the index most. For example, high utilities risk suggests scans, isolation plans, and shutdown windows. High permits risk supports early submissions and inspection tracking. High occupancy risk calls for phased zones, dust control, and safety separation. These actions reduce both likelihood and impact.
Using results for governance
Use the outputs as a planning baseline, not a guarantee. Re-score when design milestones change, bids arrive, or exploratory openings confirm site conditions. Track the index in weekly site meetings alongside change orders and schedule variance. If the index drops after investigations, you can release contingency or compress float with confidence. If it rises, escalate decisions early and document the rationale for key stakeholders.
FAQs
What does the risk index represent?
It is a normalized score from 0 to 100 built from your weighted 1–5 ratings. Higher scores indicate greater likelihood of surprises, rework, delays, and cost growth during renovation.
How should I choose a risk profile?
Use Balanced for typical projects. Choose Conservative when hidden conditions or compliance uncertainty dominate. Choose Aggressive for fast-track delivery where schedule and resource volatility are critical drivers.
Is the recommended contingency a contract requirement?
No. It is a planning recommendation derived from your inputs. Compare it with historical performance, procurement strategy, and contract terms, then set a contingency that matches your risk appetite and controls.
Can I use this for phased or occupied renovations?
Yes. Rate occupancy, access, and schedule factors based on the worst phase. Re-score per phase if risks differ, and manage buffers separately to avoid overfunding low-risk phases.
How often should I update the ratings?
Update after design changes, investigative openings, permit feedback, or major procurement updates. A monthly refresh is common, and a quick re-score after any major surprise helps keep buffers aligned.
Why do the top drivers matter?
Drivers identify which factors are pulling your score upward the most. Targeting those areas with surveys, scope clarification, and logistics planning usually reduces both cost exposure and schedule uncertainty faster.