Winning the extension of time is only half the battle. The time-related money — prolongation costs — is where claims are most often cut down. This guide covers what you can claim, and the evidence that makes it stick.
What prolongation costs cover
- Site overheads: staff and supervision, site accommodation, plant standing time, utilities, security — the running cost of being on site longer.
- Head-office overheads: claimed via formulae (Hudson, Emden, Eichleay) or, better, actual records showing unabsorbed overhead.
- Other heads: bonds and insurances extended, escalation where the contract allows, and financing costs where recoverable.
The rules that decide recovery
Costs must flow from the compensable delay — an EOT for neutral events like exceptional weather usually brings time relief only. Recovery is assessed for the period when the delay occurred, not at the end of the contract. Where your own culpable delay ran concurrently, expect the “time but no money” outcome — see our article on concurrent delay.
Proving the loss
- Break costs down month by month against the delay window — a lump sum invites a lump-sum rejection.
- Support each head with contemporaneous records: payroll, plant hire invoices, utility bills, insurance endorsements.
- Show mitigation: demobilised plant, redeployed staff, and reduced running costs strengthen credibility.
Preparing a prolongation claim, or answering one? Talk to us — we build the delay analysis and the cost substantiation together, so they tell one consistent story.