The practice

A construction project is delayed.

The schedule slips, materials arrive late, subcontractors have to be rescheduled, and costs increase. Then almost always the same discussion arises:

“Who is responsible for the delay?”

And just as importantly:

“Does this delay entitle the contractor to extra time or extra money?”

In practice, contractors often think that every disruption automatically leads to an extension of time or compensation for additional costs. Principals, on the other hand, often think that delay is simply part of construction.

Legally, the reality is much more nuanced.

A recent opinion of the Advocate General to the Dutch Supreme Court dated 22 May 2026 once again shows that courts assess delay claims strictly, especially where:

• the delay has not been substantiated sufficiently;
• it is unclear what consequences the delay actually had; or
• contractual procedures have not been followed correctly.

For both contractors and principals, this can have major financial consequences.

The legal point

When it comes to construction delay, everything legally revolves around one central question:

Did the delay actually affect the agreed completion date?

Not every delay or disruption is automatically legally relevant. Only delays on the so-called critical path of the project may entitle a party to an extension of time.

In concrete terms, this means:

• there must be a direct connection between the event and the eventual delay to the project;
• the contractor must be able to demonstrate this properly; and
• general complaints or broad references to disruptions will usually be insufficient.

In the case in question, an extensive delay analysis by an expert played an important role. Nevertheless, the court did not simply accept that analysis at face value.

This once again confirms that a delay claim only has a realistic prospect of success where:

• it is clear which event caused the delay;
• the impact on the schedule is explained concretely; and
• this is properly documented.

It also again shows how important contractual arrangements are.

In the event of changes or variation work, additional costs and possible delay often have to be notified immediately. If that is not done, those costs may later no longer be recoverable.

Also important:
an extension of time does not automatically mean there is also an entitlement to additional payment.

Separate conditions and liability rules generally apply to cost compensation.

What does this mean for contractors and principals?

For contractors, this opinion shows how important a well-maintained file is.

Anyone claiming delay must be able to show:

• what caused the delay;
• what the consequences were for the schedule; and
• that contractual procedures were followed correctly.

For principals, the opinion confirms that courts continue to scrutinise the substantiation of claims critically.

As a result, a poorly substantiated claim, or one that is notified too late, runs a significant risk of failing.

In practice, the question is therefore often not only whether delay has occurred, but above all:

• how that delay has been recorded;
• which arrangements are included in the contract; and
• whether the parties acted with due legal care during the project.

Legally sharp – tips for businesses

For contractors

• Record delays in writing immediately.
• Document the consequences a disruption has for the schedule.
• Notify variation work and delay-related costs in time.
• Ensure you have a well-substantiated delay analysis.
• Check contractual notification and warning obligations carefully.

For principals

• Examine critically whether the delay actually affected the final completion date.
• Properly record changes, instructions and communications.
• Monitor contractual deadlines and procedures.
• Have delay analyses reviewed on their merits.
• Include clear contractual arrangements on delay and additional costs.

Questions for businesses

For contractors

• Can you demonstrate exactly what caused the delay?
• Is it clear what impact the delay had on the completion date?
• Were notifications and warnings given in time?
• Is your file complete enough for legal proceedings?

For principals

• Is the alleged delay sufficiently substantiated?
• Were contractual procedures followed correctly?
• Is there demonstrable damage?
• Do any limitations of liability apply?

Especially in delay disputes in construction, a well-kept file often proves decisive.

In conclusion

Would you like to know how strong your legal position is in the event of a construction delay or a delay claim?

Please feel free to contact us without obligation. We are happy to think along with you about a practical and legally sustainable approach.