Liquidated & Ascertained Damages (LADs) in UK Construction

By

John Biggs

Reviewed by 

Nicholas Dunbar

and Zoe Mullan

Last Updated Mar 2, 2026

By

John Biggs

Reviewed By

Nicholas Dunbar

and Zoe Mullan

Staying on programme is one of construction's greatest challenges. Contractors must juggle multiple clients' deadlines, labour, and plant – and when delays occur, the consequences extend well beyond inconvenience. Contracts between employers and contractors frequently contain a Liquidated and Ascertained Damages (LADs) clause, holding the contractor liable for damages if they fail to complete on time.

Understanding LADs in Construction

In the UK construction industry, Liquidated and Ascertained Damages (LADs) represent a fixed sum, agreed upon in the contract, that the contractor pays to the employer for every day the project runs beyond the agreed Practical Completion date.

Specifically, liquidated damages cover the costs for each day the project exceeds the Completion Date. Employers typically withhold these funds from the interim payment via a Pay Less Notice for the work – a deduction that impacts the contractor's preliminaries and margin.

Qualifying Factors for Liquidated Damages

Under English law, for an LAD clause to hold up in court, it must reflect a genuine pre-estimate of loss. The clause cannot serve as a penalty designed purely to punish the contractor. If a court finds the sum to be "extravagant and unconscionable" in comparison to the greatest loss that could conceivably follow from the breach, judges may strike down the clause as an unenforceable penalty. It should be noted that this language derives from the pre-2015 Dunlop test; the current legal position, as updated by Cavendish Square Holding BV v Talal El Makdessi [2015], is addressed in the "Case Studies" section below.

The Date of Practical Completion

Employers tend to favour liquidated damages clauses because they feel these provisions protect them from project delays, as well as subsequent inconvenience or monetary loss.

At the outset of a project, the employer and contractor typically agree on a "Practical Completion date," which they define as when the finished project will be ready for use. Once project managers deem a project practically complete, the accrual of liquidated damages stops running – provided that any remaining outstanding works or snags don't prevent beneficial occupation.

The Legal Framework for LADs

LexisNexis defines a liquidated damages clause under English law as "a clause whereby the parties to a contract fix in advance a sum of money to be paid by the defaulting party to the innocent party in the event of a breach."

Even if parties mutually agree upon such a clause in writing before the Date of Possession, certain specific conditions must be met for courts to enforce the provision.

LADs in Standard Form Contracts

Most UK construction projects use standard forms, which incorporate LADs in specific ways:

• JCT (Joint Contracts Tribunal)

  Contract administrators typically insert LADs in the Contract Particulars. If they leave this section blank, general damages may apply instead.

• NEC (New Engineering Contract)

  The current edition, NEC4, uses the term "Delay Damages" under secondary Option X7. It is worth noting that the NEC4 Engineering and Construction Contract does not use the terminology "liquidated damages" itself, though the mechanism operates on the same principle.

In both cases, the Contract Administrator or Project Manager plays a vital role in certifying the completion date.

Do LADs Apply After Termination?

One frequently asked question in UK law concerns whether LADs continue to accrue if the contract terminates before contractors complete the work.

The Supreme Court ruling in Triple Point Technology, Inc v PTT Public Company Ltd [2021] UKSC 29 – which, while concerning an IT contract, has broad application to construction – clarified that, unless the contract states otherwise, LADs accrue up to the date of termination and any rights accrued as at that date survive. After that point, the employer must seek general damages for the remaining delay.

Determining Fault for Delays

For courts to enforce liquidated damages clauses, they must determine who bears fault for any delays and whether the project delay qualifies as excusable. Delays can stem from the contractor, the employer, or a combination of the two. That decision determines who, if anyone, faces liability for any liquidated damages that may have accrued if a dispute ends up in court.

Project Contingency Planning

Many contractor estimates include a portion of the overall project budget allocated to cover unpredictable risks, known as a Contractor's Risk Allowance. Contractors often face unexpected costs, including delays. Similarly, employers maintain contingency reserves in the event that project teams modify work while it's underway. If an employer drastically changes the project scope and causes a delay, it would be difficult for any reasonable person to conclude that the contractor bears responsibility.

Calculating Liquidated Damages

Calculating liquidated damages can be tricky, depending on the project. An employer developing a commercial office or residential project might have an easier time proving loss of revenue resulting from a delayed opening than, say, the employer opening a library or a highway infrastructure project.

If challenged in court, the employer generally must prove how they arrived at the figure they included in the liquidated damages provision in the Contract Particulars. Other considerations that employers can calculate for possible liquidated damages include loss of rent, increased financing costs, and extended site overheads.

Example Calculation

Unlike general damages, LADs do not require the employer to prove actual loss after the fact. Instead, parties calculate the rate beforehand. For example, if a commercial unit faces delays, contract parties might set the LADs at £1,000 per week, calculated based on:

• Loss of rental income (£600)
• Extended financing costs (£200)
• Storage for equipment (£100)
• Extended site preliminaries (£100)

This approach creates commercial certainty for both parties.

Enforcing Liquidated Damages Provisions

For courts to enforce liquidated damages provisions, the amount must offer a proportionate protection of legitimate interest.

Liquidated damages do not aim to punish contractors, and thus cannot reach an amount that courts would consider excessive or punitive. For example, a calculated rate commensurate with the employer's anticipated loss would meet the standard of reasonableness. The employer can't choose an amount so high that it wouldn't withstand a legal challenge.

Furthermore, the employer might need to prove that the amount matches their anticipated actual monetary losses and demonstrate how they calculated the figure in the contract. The enforceability of liquidated damages can also hinge on who bears blame for the delay, as explained above. If the employer caused the delay or directly contributed to it themselves, collecting liquidated damages could be much harder, if not impossible. A court could even grant a contractor an extension before the damages start accruing if judges deem the reason for the delay excusable.

The Non-Completion Notice

Under JCT contracts, the employer (or Architect/Contract Administrator) must issue a formal Non-Completion Certificate before they can deduct LADs. If contract administrators fail to issue the correct Pay Less Notices and non-completion certificates in accordance with the Housing Grants, Construction and Regeneration Act 1996, the employer may lose the immediate right to deduct these damages from interim payments.

Additionally, failing to meet each of these deadlines could subject the contractor to liquidated damages, which can accumulate if teams miss multiple milestone dates.

When late completion or missed milestones occur, the Contract Administrator must reasonably estimate the employer's damages for a liquidated damages provision to hold up in court. Those findings must adhere to the previously mentioned requirements, or an adjudicator or court could strike out the liquidated damages clause.

Case Studies: LADs in Practice

A notable example involves the construction of Wembley Stadium. The project faced significant delays, leading to complex disputes between the main contractor, Multiplex and various parties, including the steel subcontractor, Cleveland Bridge. The related case of Multiplex Constructions (UK) Ltd v Honeywell Control Systems Ltd [2007] directly addressed the prevention principle in this context, establishing that for LADs to be enforceable, the employer must not have committed acts that prevented the contractor from completing on time.

In Cavendish Square Holding BV v Talal El Makdessi [2015] UKSC 67 – a share purchase case with wider application to contract law – the Supreme Court updated the previous test for penalty clauses established in Dunlop Pneumatic Tyre Co Ltd v New Garage and Motor Co Ltd [1915]. Rather than asking simply whether a clause was a genuine pre-estimate of loss, the Court established that the operative question is whether the clause imposes a detriment out of all proportion to the innocent party's legitimate interest in enforcing the primary obligation. 

Strengthening Relationships Through Fair Practices

Insurance & Commercial Risk

LADs function not just as a legal mechanism but as a risk management tool. Accurately set, LADs help insurers assess Delay in Start-up (DSU) policies. For the contractor, a capped LAD figure limits liability exposure, allowing for more accurate cash flow forecasting and risk pricing during the tender stage.

To reduce the likelihood of ending up in court over a liquidated damages dispute, parties should handle such provisions methodically. Milestone deadlines should be as achievable as possible while still fitting within the employer's timeline, and contract draughtsmen should under no circumstances design liquidated damages clauses as a punitive measure.

Good Faith Agreements

Both employers and contractors should approach agreements in good faith. Adhering to the express terms of the contract ensures that if a project faces delays, parties can avoid costly litigation:

• Relevant/Compensation Events

  Contract parties should apply the contract mechanisms for Extension of Time (EOT) and Loss and Expense.

• Employer Instructions

  When the employer initiates variations, these should result in a formal adjustment of the Completion Date and Contract Sum.

• Contractor Proposals

  If a contractor requests a variation for their own convenience, they must bear the associated costs and risk to the programme.

• Proportionate Provisions

  When parties design LADs to be compensatory rather than punitive, they significantly increase the likelihood of settling disputes amicably.

Preventing Financial & Reputational Risks

All parties seek to avoid litigation if they can, and designing liquidated damages provisions in accordance with what courts will enforce and what is fair offers the best path forward. Fighting a protracted legal battle over a missed deadline can sap even more time and resources from a company already stretched thin, which is why parties should always abide by the contract.

This approach is, of course, contingent on the contract itself being robust, fair, and unlikely to require a legal challenge to settle.

Written by

John Biggs

John Biggs is an entrepreneur, consultant, and writer. Biggs spent 15 years as an editor for Gizmodo, CrunchGear, and TechCrunch. His work has appeared in Men’s Health, Wired, and the New York Times.

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Reviewed by

Nicholas Dunbar

Content Manager | Procore

65 articles

Nick Dunbar oversees the creation and management of UK and Ireland educational content at Procore. Previously, he worked as a sustainability writer at the Building Research Establishment and served as a sustainability consultant within the built environment sector. Nick holds degrees in industrial sustainability and environmental sciences and lives in Camden, London.

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Zoe Mullan

27 articles

Zoe Mullan is an experienced content writer and editor with a background in marketing and communications in the e-learning sector. Zoe holds an MA in English Literature and History from the University of Glasgow and a PGDip in Journalism from the University of Strathclyde and lives in Northern Ireland.

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