When two delays run at the same time

Concurrent delay is where two delaying events run over the same period, one at the employer's risk and one at the contractor's, and either would have delayed completion on its own. It is the single hardest assessment a contract administrator has to make, and it attracts more argument per week of delay than anything else in construction.

It is claimed far more often than it occurs

Genuine concurrency requires both events to be effective causes of the same delay to completion. Most of what gets labelled concurrent is sequential: one event delays the works, and a second arises during the period the first has already created.

That is not concurrency. If the works were already going to finish late because of event A, and event B arises in that period without extending the finish date any further, B has caused no delay to completion at all.

The general position

Where delay is truly concurrent, the position most commonly applied in England and Wales is that the contractor gets an extension of time but not loss and expense.

The reasoning is that the two questions are answered by different tests. For time, the contractor needs only to show that a relevant event caused delay, and it has. For money, it needs to show that the loss was caused by the employer's event, and it cannot, because its own concurrent delay would have caused the same loss anyway.

The practical result is relief from liquidated damages without recovery of prolongation costs. Both parties end up bearing something, which is usually a sign that the answer is roughly right.

It can be contracted out of

Some contracts now include express concurrency clauses, often stating that where delay is concurrent the contractor gets no extension at all. These have been upheld. If you are working under an amended form, read the delay provisions before assuming the general position applies, because it may have been displaced entirely.

What makes an assessment survive

Contemporaneous records. Not a retrospective narrative, but what was recorded at the time: progress reports, site diaries, the programme as it stood that month, and the notices as they came in.

A delay analysis built two years later from correspondence is an argument. One built from records kept as the delay happened is evidence, and the difference is visible immediately.

The mistake that costs most

Refusing an extension because the contractor was also in delay, without assessing whether the employer's event independently caused delay to completion. That conflates the time test with the money test and produces a decision that will not stand.

The opposite error, granting both time and money because an employer event is somewhere in the picture, is less common but equally wrong, and considerably more expensive.

How to write it down

State which relevant event is relied on, the period claimed, the period awarded, whether any part of it was concurrent with contractor delay, and what follows for loss and expense. Four sentences, written when the decision is made.

Every hour spent on that at the time is worth a week of reconstruction later, and it is the difference between a decision that can be defended and one that merely has to be.