Concurrent delay in England and Wales

Definitions and the cross-border comparison are on the neutral concurrent delay page; the forms and the wider authority map are on the England and Wales extension of time hub.

The default is time yes, money no, and every step of its chain is first instance

Jurisdictional: England and Wales. Only step 6 is appellate, and it did not decide the default.

Read in order, the chain shows its weakness: a concession at the foundation, a High Court judgment as the clearest statement, and a recent application on agreed law. In the Court of Appeal, Coulson LJ called the position "not entirely free from doubt" (¶17) but found it "unnecessary to resolve" (¶18). A TCC judge or adjudicator can be expected to apply the default. (Opinion.) It is still not settled law.

Walter Lilly gives the full extension; the money rule is borrowed from De Beers

On time, in Walter Lilly & Co Ltd v Mackay (11 July 2012) Akenhead J set out the English and Scottish approaches (¶366) and chose the English one. On the extension of time clause in that contract, where delay is caused by two or more effective causes, one of them a Relevant Event, "the Contractor is entitled to a full extension of time" (¶370). He then dealt with Scotland directly: "the City Inn case is inapplicable within this jurisdiction" (¶370). His reasoning was that a duty to fix a fair and reasonable date does not imply apportionment where there is concurrency.

On money, the judgment quotes the rule rather than making it. At ¶368 Akenhead J sets out the formulation of Edwards-Stuart J in De Beers at [177]: where concurrent delay to completion is caused by matters for which both employer and contractor are responsible, the contractor gets the extension of time but cannot recover the loss caused by the delay. De Beers was an IT services contract; its reasoning, in paraphrase, is that the contractor must have a reasonable time to complete, so it does not matter that it would have missed the contractual date anyway.

The two halves rest on different tests. Time asks whether the Relevant Event was an effective cause. Money asks whether the loss would have been suffered but for the Employer's event, and a concurrent Contractor cause defeats that.

Adyard narrows concurrency before the rule is ever reached

The rule only bites if the delays are genuinely concurrent, and Adyard Abu Dhabi v SD Marine Services (Hamblen J, 11 April 2011) sets a strict threshold for that:

"there is only concurrency if both events in fact cause delay to the progress of the works and the delaying effect of the two events is felt at the same time" (¶279)

The test is factual and actual. Prevention means "prevention in fact; not prevention on some notional or hypothetical basis" (¶264). Where the Contractor was already in critical delay on its own account when the Employer's event arrived, the Employer will argue that its event delayed nothing that was not already late, and that there is no concurrency to apply a rule to. (Inference.) Adyard also states the English answer where genuine concurrency is found: in contrast to the last of the scenarios Lord Osborne described in City Inn, "the builder is entitled to an extension of time, not an apportionment" (¶288), citing Malmaison.

That first-in-time argument is contested. The Court of Appeal in North Midland quoted ¶279 and noted that Walter Lilly points the other way from the textbook view relying on Adyard (¶17), then left the difference unresolved (¶18). Even so, the Employer's best line is often not to attack the rule but to show that the Contractor's delay came first and was already critical. (Opinion.)

Thomas Barnes applied the agreed rule to concurrent delay and split the outcome

Thomas Barnes & Sons plc (in administration) v Blackburn with Darwen BC (HHJ Stephen Davies, 17 October 2022) concerned a bus station built under a JCT form with cl 2.29A (Amendment 1A) applying (¶146). It is the leading recent trial decision applying the default.

The law was agreed, not argued. At ¶118 counsel agreed the test (from Keating, citing De Beers [177], Adyard and Walter Lilly [370]): an extension of time is due if the Relevant Event was an effective cause of delay even if there was a concurrent Contractor cause; loss and expense requires the but-for test, and showing a dominant cause is not enough.

The delays were found concurrent. The hub steelwork remedial delay (an Employer risk) and the roof coverings delay (a Contractor risk) were both causes of the critical delay (¶¶140, 143–144). This was a concurrency case on its facts, not a case where concurrency failed.

The outcome split time from money. The Contractor received an extension of time of 119 days (¶148; to 10 August 2015, ¶14(a)). It recovered no loss and expense for the concurrent period (¶147), and prolongation only for "27 days net of the concurrent delay" (¶148).

On method, the court did not prescribe one. At ¶110 the judge rejected the submission that an expert is "only allowed to choose one such method and any deviation from that stated approach renders their opinion fundamentally unreliable"; a manifestly inappropriate method goes to weight. The as-built critical path approach was the claimant's expert's method (¶137), not a direction by the court. See delay analysis methods.

North Midland: you can contract out, and the Court of Appeal left the default open

North Midland Building Ltd v Cyden Homes Ltd (Sir Terence Etherton MR, Sir Ernest Ryder SPT and Coulson LJ, 30 July 2018) concerned an amended JCT Design and Build 2005 contract with a bespoke cl 2.25.1.3(b): "any delay caused by a Relevant Event which is concurrent with another delay for which the Contractor is responsible shall not be taken into account". The Contractor's prevention argument failed and the appeal was dismissed.

• The prevention principle is not "an overriding rule of public or legal policy" (¶30). It can be displaced by clear words, and these words were clear.
• No term could be implied to stop the Employer levying liquidated damages for the concurrent period; it would contradict the express terms (¶45).
• The default position, absent such a clause, was "not entirely free from doubt" (¶17) and "unnecessary to resolve" (¶18).

A Cyden clause reverses the outcome on the same facts: no extension for the concurrent period, and liquidated damages run. Employer amendments to JCT and NEC forms increasingly include one, and they appear in English-law EPC contracts too. (Opinion.) TTSJV W.L.L. v BapCo Refining [2026] EWHC 2047 (TCC) only noted such a bar (cl 8.3(d), ¶46); the extension argument failed on other grounds (¶¶48–51). On how such clauses interact with prevention, see the prevention principle and time at large page.

A Cyden clause bites only on delay that is genuinely concurrent, so the Adyard threshold still has to be crossed. (Inference.) Because it removes time for Employer-caused delay, expect it to be read strictly; the North Midland wording was unambiguous. (Opinion.)

Scotland apportions, and England has said it will not

City Inn Ltd v Shepherd Construction Ltd [2010] CSIH 68 (Extra Division: Lord Osborne, Lord Kingarth, Lord Carloway; 22 July 2010), affirming Lord Drummond Young at first instance, holds by a majority (Lord Osborne and Lord Kingarth) that where both causes operate and neither is dominant, it is open to the decision-maker to "apportion the delay". Lord Carloway concurred in the result but rejected apportionment. [SINGLE-SOURCE] It is an appellate decision and it has not been overruled.

English courts have refused to follow it: Walter Lilly ¶370 held it inapplicable in England, and Adyard ¶288 put the English answer as an extension of time, not an apportionment. The split is unresolved and would need the UK Supreme Court to close it. (Opinion.) Until then, a project in Scotland or a contract governed by Scots law can produce a different day count on identical facts, so the governing law clause matters on any cross-border job. (Inference.) Compare the form-driven answers in Australia and the apportionment trend in Canada.

JCT 2024 and NEC4 leave concurrency to the general law

JCT 2024. The printed form does not address concurrency, although North Midland (2018) showed how a clause could. The default therefore applies unless the parties amend. The form's own time-without-money outcome for epidemic and change in law (Relevant Events, but Relevant Matters only if selected) is contractual allocation, not concurrency. [NEGATIVE FINDING] No reported English judgment construes the JCT 2024 extension of time provisions as at 13 October 2026; every reported 2025–26 JCT decision Storia found was on a 2016 or earlier edition. On the Standard Building Contract the 2016 numbering is 2.27 / 2.28 / 2.29; check the 2024 form.

NEC4 ECC. NEC has no extension of time clause: time relief is a change to the Completion Date, assessed under cl 63.5 against planned Completion on the Accepted Programme. There is no concurrency provision. Since the January 2019 amendments, cl 63.5 takes account of delay already in the Accepted Programme and of events between the Accepted Programme date and the dividing date (paraphrased). The Contractor's own slippage is therefore dealt with implicitly: if the Accepted Programme already shows the Contractor late, the compensation event is measured from that late position. (Inference.) [NEGATIVE FINDING] No English judgment on NEC concurrency was located (searched 13 October 2026). Under NEC the question may never arise, because a compensation event notified late under cl 61.3 (8 weeks from awareness) changes neither the Prices nor the Completion Date, unless it arises from the Project Manager or Supervisor giving an instruction or notification, issuing a certificate or changing an earlier decision. (Opinion.) See notice and time bars.

The money side turns on segregation, not on the label

Because loss and expense needs the but-for test (Thomas Barnes ¶118), concurrency usually defeats prolongation for the concurrent period. The way back is to separate the costs. The SCL Delay and Disruption Protocol, 2nd edition (February 2017) takes the same line as the English default on both halves: Core Principle 10 says concurrent Contractor Delay should not reduce the extension of time due, and Core Principle 14 allows prolongation cost only where the Contractor separates the costs caused by Employer Delay from those caused by its own. (Opinion.) The Protocol is guidance, not law. Thomas Barnes shows the time-based version: prolongation for the 27 days of delay left once the concurrent period was netted off (¶148), not for the whole 119.

Where the Contractor runs a global claim instead, Walter Lilly ¶486(e) holds that matters at the Contractor's own risk do not necessarily defeat the claim: the sum attributable to them is deducted from the global loss. Quantum is covered on prolongation and delay costs.

What is not settled

• The default itself. Every authority on the rule absent express words is first instance, resting on an agreed position (Malmaison), and the Court of Appeal left it open (North Midland ¶¶17–18).
• Recent reconsideration. [NEGATIVE FINDING] No English decision between 2023 and 13 October 2026 squarely reconsiders the default rule (searches re-run 13 October 2026).
• NEC concurrency and JCT 2024. No English authority on either.
• The England and Scotland split. Unresolved.

Where Storia fits

Concurrency in England is decided on the record of what was critical, when, and whether the two delays were felt at the same time. Storia's claims and dispute resolution tools link each delay event to the programme update, the site records and the cost codes that existed at the time, so the Adyard question and the cost separation can be answered from contemporaneous evidence rather than reconstructed for an adjudication.

Sobre este material El contenido de la biblioteca es información general sobre la práctica de las reclamaciones de construcción, no asesoramiento jurídico. El derecho a reclamar, los plazos y el procedimiento se rigen por su propio contrato y por el derecho del lugar donde se ejecuta la obra. Revisado el 13 de octubre de 2026 · Informar de una corrección