In brief: What concurrent delay is, how it affects extensions of time, prolongation costs and liquidated damages, and how delay analysts separate true concurrency from overlapping delays.
Concurrent delay is one of the most argued issues in construction claims. It decides whether a contractor gets an extension of time, whether it is paid for the delay period, and whether the employer can deduct liquidated damages. This article explains what concurrent delay means, how it is commonly assessed, and what records are needed to deal with it.
What is concurrent delay?
The SCL Delay and Disruption Protocol describes true concurrent delay as the occurrence of two or more delay events at the same time, one an employer risk event and the other a contractor risk event, where the effects of both are felt at the same time. Both events must be effective causes of delay to completion. If one event would not have delayed completion on its own, because it only used float, the delays are not concurrent.
In practice, true concurrency is rare. More often, delays overlap in time but only one of them is on the critical path. Separating real concurrency from overlapping delays is the main task of the analysis.
Time: is an extension of time still due?
Under the SCL Protocol, and in the approach often applied in English law, where an employer delay and a contractor delay are truly concurrent, the contractor is entitled to an extension of time for the employer delay. The contractor’s own delay does not reduce that entitlement. This prevents the employer from claiming liquidated damages for a period it partly caused.
Other legal systems and contracts take different approaches, including apportionment. FIDIC 2017 Sub-Clause 8.5 refers concurrency to the rules in the Special Provisions. Some amended contracts state expressly that no extension is granted for concurrent periods, and in England the Court of Appeal upheld such a clause in North Midland Building v Cyden Homes (2018). Always check the contract wording first.
Money: is prolongation cost recoverable?
Under the SCL approach, the contractor is generally not paid prolongation costs for a period of true concurrent delay, unless it can separate the costs caused by the employer event from those caused by its own delay. In short: time, but no money, for the concurrent period.
This makes the analysis of concurrency important for both sides. The contractor wants to show that its delay was not critical. The employer wants to show that the contractor would have been late anyway. See our article on quantum in construction claims for how prolongation costs are calculated.
How concurrent delay is analysed
- Identify the critical path in each period using the contemporaneous programme updates or an as-built critical path.
- List all delay events on or near the critical path in that period, both employer and contractor risk.
- Test each event to see if it would have delayed completion on its own.
- Check timing. Two delays that affect the critical path at different times are sequential, not concurrent.
- Look at pacing. A contractor that slows down because the employer’s delay has already pushed completion may be pacing, not causing concurrent delay. This needs evidence of a decision made at the time.
Windows analysis is often used because it shows the critical path and the delays in each period. Our guide to delay analysis methods compares the options.
Records that matter
- monthly programme updates showing the critical path and float at the time
- progress reports that explain the causes of slippage as they happened
- daily reports and resource records showing whether the contractor was ready to work
- correspondence where either side raised delays or reserved its position
Employers often raise concurrency late, in response to a claim. A contractor whose monthly reports already explain contractor-side issues and their effect on float is in a much stronger position.
Frequently asked questions
Is concurrent delay the same as overlapping delay?
No. Delays can overlap in time without both affecting completion. Only delays that are each an effective cause of delay to completion, at the same time, are truly concurrent.
Can a contractor avoid liquidated damages if there was concurrent delay?
Under the SCL approach and many common law decisions, yes for the concurrent period, because an extension of time is granted for the employer’s delay. A contract can change this, so the wording must be checked.
Does FIDIC deal with concurrent delay?
FIDIC 2017 Sub-Clause 8.5 says concurrent delay is assessed under the rules in the Special Provisions. FIDIC 1999 does not address it directly, so the governing law and the facts decide.
Solvix assesses concurrent delay as part of EOT claims, claims defence and expert witness work.
