By Mark Sayer I Insights
Who Pays When the Clock Keeps Ticking?
Prolongation Costs and EOT: Whole Site or Just the Delayed Works?
You’ve secured an Extension of Time (EOT); a relief in itself. But now comes the real question: can you recover prolongation costs for the entire site or only for the specific sections delayed? It’s one of the most common post-EOT debates in construction claims and one that often ends up in dispute resolution.
Let’s break it down.
What Are Prolongation Costs?
Prolongation costs are the additional expenses incurred by a contractor because the project took longer than planned through no fault of their own. These typically include:
• Site preliminaries (e.g. site security, temporary works, facilities)
• Staff salaries
• Equipment hire
• Site accommodation
• Insurance and utilities
The Core Issue
The key distinction lies here:
• Full Site Recovery: The contractor claims prolongation costs for the entire project setup, even if only certain portions of the works were delayed.
• Part Works Recovery: The contractor recovers only for the resources directly affected by the delay.
So, what’s recoverable? That depends.
What Determines Entitlement?
Several factors shape the answer:
1. Contract Language
Most standard forms (e.g. FIDIC, JCT, NEC) provide for recovery of direct loss and/or expense, but the burden of proof lies with the contractor. The contract might:
• Be silent on whole-site recovery
• Impose “causation” and “reasonableness” tests
• Require demonstration of actual cost impact
Check clauses related to Claims, Compensation Events, or Prolongation Costs.
2. Nature of the Delay
If the delay impacts critical path activities, it’s more plausible to argue that site-wide costs were extended. If the delay is sectional or localised, it may be difficult to justify whole-site prolongation.
3. Inseparability of Site Setup
Sometimes, resources are so integrated (e.g. shared cranes, site offices, scaffold systems) that separating the delayed works from the rest of the site becomes impractical or impossible. In such cases, contractors may reasonably argue for full-site cost recovery.
4. Demonstrable Loss
No matter the argument, the contractor must provide:
• Clear cause-effect linkage between the delay and cost
• Accurate records of resources and costs incurred
• Evidence that the prolongation wasn’t caused by contractor inefficiency
What Have Courts and Arbitrators Said?
UK case law (e.g. Walter Lilly v Mackay [2012]) and various arbitral decisions have generally supported the principle that, where a contractor proves that they were prevented from demobilising, they may recover full-site prolongation costs even for undelayed portions if those site-wide costs were genuinely extended as a result. However, the bar remains high: assumptions won’t cut it. The courts require precise cost analysis and time-impact assessments.
Best Practice for Contractors
To maximise recoverability:
• Keep daily records of labour, plant, prelims
• Maintain version-controlled programme updates
• Link delay events to specific cost centres
• Use expert delay and quantum consultants where necessary
Final Word
An EOT doesn’t guarantee automatic reimbursement of every extended cost. But with the right records, analysis, and strategy, contractors can strengthen their case for full-site recovery especially when delays ripple across shared infrastructure or compound inefficiencies.
The lesson? Don’t just win the time. Prove the cost.
Written by:
XX, Risk & Advisory Lead at Middleton
Supporting better decisions through clarity, accountability, and legal alignment.