What extension-of-time and financial entitlement arises where employer and contractor delays operate concurrently?
Concurrent delay does not produce one universal result. The contract, the critical effect of each event and the governing law must be analysed separately for time and monetary relief.
An effective employer-risk cause may support an extension of time despite concurrent contractor delay, but financial recovery requires proof that the compensable event caused the claimed loss
Under the English approach applied in Thomas Barnes, a contractor may obtain time where an employer-risk event was an effective cause of critical delay even though a contractor-risk event operated concurrently. That does not establish loss and expense for the same period. The contractor must prove that the compensable event caused the claimed cost and answer the position that the cost would have arisen from its own delay in any event. The precise contract wording remains decisive. Scottish authority has accepted apportionment in circumstances that should not be assumed to govern an English contract.
| Issue | Position |
|---|---|
| Employer-risk event effectively delays completion | Potential extension of time |
| Contractor-risk delay operates concurrently | Does not necessarily defeat time entitlement |
| Concurrent prolongation cost | Requires separate causation and contractual entitlement |
| Cost would arise from contractor delay anyway | Financial recovery may fail |
| Apportionment | Jurisdiction and contractual basis must be checked |
Concurrency requires critical causation
Two events are not legally concurrent merely because they occur during overlapping calendar periods. Each must be examined against the works sequence and the completion obligation. The enquiry is whether both events were effective causes of delay to completion during the period under review. An event affecting non-critical work, consuming unused float without delaying completion, or arising after completion was already fixed by another cause may not establish true concurrency.
Plot each event against the contemporaneous critical path and determine when, if at all, it independently affected completion.
Time and money are different enquiries
An extension of time adjusts the contractual completion obligation and may protect the contractor from delay damages for the relevant period. Loss and expense or damages compensate proven financial consequences of a compensable event. The grant of time does not itself prove that the employer caused the contractor's prolongation cost, and refusal of cost does not necessarily defeat the extension of time.
Malmaison: the time principle
The parties agreed that where a relevant event and a non-relevant event concurrently caused the same delay, the contractor was entitled to an extension for the delay caused by the relevant event. The example concerned adverse weather operating with a labour shortage. The decision is commonly used to explain why contractor culpability does not automatically extinguish time entitlement.
Fairweather: do not force all delay into one dominant head
An arbitrator allocated an extension solely to the dominant reason. The court rejected that treatment and held that, where delay corresponded with more than one contractual head, the extension could be granted under either or both heads. The authority does not establish a universal dominant-cause rule for all delay disputes.
John Doyle and City Inn: Scottish treatment
The Scottish court considered dominant cause and, where no dominant cause could be identified, possible apportionment of loss where employer events were a material cause operating with other causes.
The Inner House accepted a fact-sensitive approach under which a dominant cause could be applied, or delay could be apportioned where a relevant event and contractor-responsible event both materially operated and neither dominated. This Scottish approach should not be presented as an English rule.
Thomas Barnes: current English application
The TCC treated remedial structural-steel delay and contractor-responsible roof delay as concurrent causes affecting the critical path. The contractor obtained an extension of time for the concurrent period but could not recover loss and expense for that same period. The court awarded a 119-day extension while limiting prolongation recovery to 27 days after allowing for concurrent contractor delay.
What Thomas Barnes establishes
| Principle | Effect |
|---|---|
| Contract wording first | The court stated the principles subject to the precise contractual terms. |
| Effective cause supports time | An employer-risk event need not be the sole cause of critical delay. |
| Money requires the counterfactual | The contractor must establish that its claimed loss would not have arisen from its own concurrent cause. |
| Critical-path evidence matters | The court examined when steel, roof and finishing activities actually controlled completion. |
| Net period may differ | The period attracting an extension may exceed the period attracting prolongation recovery. |
Neutral events and contractor events
A neutral relevant event may support time without carrying a contractual right to money. If it operates concurrently with an employer's breach, the contractor must still identify the compensable event and prove the cost caused by that event. If a contractor-risk event would independently have generated the same site overhead or resource cost, the monetary claim may fail for that period.
Evidence and analysis
| Evidence | Purpose |
|---|---|
| Accepted baseline | Shows the intended sequence, logic and planned critical path. |
| Contemporaneous updates | Show changing progress, float and forecast completion. |
| Event records | Fix instruction, access, design, weather, labour and defect dates. |
| As-built evidence | Shows when activities actually occurred and what controlled successors. |
| Critical-path explanation | Connects each event to completion during each period. |
| Cost records | Separate cost caused by the compensable event from contractor or neutral delay. |
Administration controls
Analyse each alleged event against the contract before applying a concurrency label.
Identify the critical path contemporaneously and update it when the sequence changes.
Assess time entitlement separately from financial entitlement.
Record the period during which each event was an effective cause of completion delay.
Test whether the claimed cost would have arisen from contractor delay in any event.
Avoid automatic dominance, first-in-time or apportionment assumptions.
State the governing law when relying on Scottish or foreign authority.
Authorities
| Authority | Citation | What it decides |
|---|---|---|
| Henry Boot Construction (UK) Ltd v Malmaison Hotel (Manchester) Ltd | [1999] 70 ConLR 32 | A relevant event may support time despite a concurrent non-relevant event. |
| H Fairweather and Co Ltd v London Borough of Wandsworth | (1987) 39 BLR 106 | Allocating all delay to one dominant contractual head was rejected. |
| John Doyle Construction Ltd v Laing Management (Scotland) Ltd | [2004] BLR 295 | Scottish authority considered dominant cause and possible apportionment of loss. |
| City Inn Ltd v Shepherd Construction Ltd | [2010] CSIH 68 | Scottish authority accepted a fact-sensitive dominant-cause or apportionment approach. |
| Thomas Barnes and Sons plc v Blackburn with Darwen Borough Council | [2022] EWHC 2598 (TCC) | Concurrent delay supported time, but financial recovery was confined to the net compensable period. |