When an employer risk event and a contractor risk event delay the same completion date over the same period, the answer to time and the answer to money are usually not the same.
The definition is the argument.
True concurrency, two effective causes operating at the same time on the same critical delay, is rare. Most pleaded concurrency is sequential: two events in the same window, only one of which is driving completion at any given moment.
Under the approach in Henry Boot v Malmaison, a contractor may obtain an extension for a relevant event notwithstanding a concurrent contractor delay, while recovering no prolongation cost for that period. Time and money separate.
The Scottish decision in City Inn v Shepherd Construction favored apportionment between causes. Walter Lilly v Mackay preferred the Malmaison approach in England. The divergence is real, and which applies is a function of the governing law.
Parties can also allocate the risk expressly. In North Midland Building v Cyden Homes the Court of Appeal upheld a clause placing concurrent delay risk on the contractor.
How concurrency is actually tested.
Concurrency is a finding about the critical path in a defined window, not a label.
Define the window
Fix the period in which both events are said to operate.
Establish criticality
Determine what was driving completion in that window, on the schedule current at the time.
Test each cause separately
Establish whether each event, on its own, would have delayed completion.
Check the sequence
Distinguish events genuinely operating together from events merely present in the same period.
Split time from money
Apply the governing law's approach to extension separately from the approach to prolongation cost.
What the argument is built from.
Concurrency arguments are won on contemporaneous criticality, not on hindsight.
Where these claims fail.
Concurrency is asserted far more often than it is established.
Concurrency is pleaded as a defense to everything
Blanket concurrency, without a window and a critical path, reads as an argument of last resort.
The events are sequential
Two delays in the same month are not concurrent if only one was ever driving completion.
The wrong approach is applied
Running an apportionment case under a governing law that follows Malmaison, or the reverse, loses on the law rather than the facts.
Money follows time automatically
An extension for a concurrent period does not, on the usual approach, carry prolongation cost with it.
What the Matter Model does with it.
It isolates competing delay events window by window and holds each against the critical path in force at the time, rather than against the final schedule.
It keeps the time answer and the money answer as separate propositions on the same record, so a concurrency finding cannot silently carry cost with it.
Standards and authorities
- Henry Boot Construction (UK) Ltd v Malmaison Hotel (Manchester) Ltd (1999) 70 Con LR 32
- City Inn Ltd v Shepherd Construction Ltd [2010] CSIH 68
- Walter Lilly & Co Ltd v Mackay [2012] EWHC 1773 (TCC)
- North Midland Building Ltd v Cyden Homes Ltd [2018] EWCA Civ 1744
General reference on how these disputes are argued. Not legal advice, and not a statement of the law of every jurisdiction or seat.
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