Liquidated damages are the pre-agreed sum the contractor pays for late completion, usually expressed per week or per day of delay beyond the completion date.
They give both parties certainty: the employer does not have to prove its actual loss, and the contractor knows its exposure. Deduction normally requires the contractual machinery to be operated correctly, and in UK practice a valid extension of time defeats LDs for the extended period.
That is why EOT and LD arguments are two sides of the same coin, and why the records that support an EOT are, in effect, the contractor’s insurance policy against delay damages.
Because they are pre-agreed, liquidated damages are not a measure of what the employer actually lost, and neither side gets to reopen that question later. An employer whose real loss was far greater is still limited to the rate in the contract. A contractor whose delay caused no measurable loss at all still pays it. Certainty runs in both directions.
Contractors resist liquidated damages on three broad fronts. The first is entitlement: a valid extension of time moves the completion date, and damages cannot run for a period that has been extended. The second is machinery: the contract usually requires certificates, notices and deductions to be issued in a particular order and within particular windows, and an employer who skips a step may lose the right to deduct even where the delay is undisputed. The third, less often successful, is that the rate is a penalty rather than a genuine attempt to deal with the consequences of delay.
The practical consequence is that a contractor facing damages is really fighting about records. Whether the delay was excusable, when it began, what caused it and what it affected are all questions answered from the daily account of the job. A contractor who cannot evidence its own delay narrative usually ends up paying the rate whatever the underlying merits.
Those records have to exist before the delay is ever argued; Construction Metric builds them daily from the site WhatsApp group, as explained on the how it works page.