Executive summary
Run execution against the contract milestones, budget baseline and schedule set in earlier stages, with formal change control, progress reporting and quality assurance throughout. Mechanical completion — the asset built and verified against specification but not yet operating — is the deliverable commissioning takes over.
This stage receives signed contracts, a mobilisation plan and an approved budget baseline from procurement planning and budget development; deviations from that baseline should go through formal change control, not informal site decisions.
The transition to commissioning depends on a clear, jointly verified definition of mechanical completion agreed before execution starts, not improvised at handover.
What this stage must resolve
- Signed contracts and mobilisation plan ready for site or fabrication start
- Multiple contractors requiring coordinated scheduling and interface management
- Budget and schedule baselines needing active variance tracking
- Quality assurance requirements not yet embedded in site inspection processes
- Safety, environmental and permitting compliance obligations active during construction
Work performed in this stage
Milestone-based progress tracking
Physical progress verified against contract milestones, not self-reported percentages.
Formal change control
Scope, cost and schedule changes documented and approved before implementation.
Interface management
Active coordination of boundaries between multiple contractors' scopes.
Quality assurance and inspection
Independent verification of work against specification at defined hold points.
Safety and compliance management
Ongoing site safety, environmental and permitting compliance through construction.
Comparison table
| Mechanism | Purpose | Consequence if absent |
|---|---|---|
| Change control | Approves scope/cost/schedule deviations formally | Uncontrolled scope and cost creep |
| Interface management | Coordinates boundaries between contractors | Disputes and rework at handover |
| Quality hold points | Verifies work before it is covered or continued | Defects discovered late, costly to fix |
| Progress verification | Confirms physical progress against claims | Payment ahead of actual delivery |
Execution governance mechanisms
Risks and governance considerations
- Uncontrolled change is the leading cause of both cost overrun and schedule slippage during execution
- Interface gaps between contractors, if not actively managed, resurface as disputes at handover
- Mechanical completion criteria should be defined and agreed before execution starts, not negotiated at the end
- Site safety incidents carry cost, schedule and reputational consequences that dwarf most other variances
What to prepare
- Signed contracts and mobilisation schedule
- Approved budget and schedule baseline
- Change control procedure and authority levels
- Quality inspection and hold-point plan
- Agreed definition of mechanical completion
What to measure
Frequently asked questions
What is mechanical completion?
The point at which the asset is built and verified against specification but has not yet been started up or proven in operation — the formal trigger for commissioning to begin.
How is scope creep controlled during execution?
Through a formal change control process requiring documented approval before any deviation from the contracted baseline is implemented.
Who verifies progress claims from contractors?
An independent project team or engineer, not the contractor's own self-reported progress, should certify progress for payment purposes.
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Global B2B Group does not sell equipment and does not represent lenders, export credit agencies or development banks. This material is published to help industrial organisations plan, structure and prepare capital projects. It is general information for decision-making, not financial, legal or tax advice.