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Delay claims6 min read

How to write a notice of delay that holds up.

Most contractors know they need to issue a notice of delay. Fewer know exactly what it must contain, how soon it must be sent, and why a vague or late notice can kill an otherwise valid extension-of-time claim before it starts.

A notice of delay is the formal trigger that keeps your extension-of-time entitlement alive. Miss the window, leave out a required element, or word it too vaguely, and the other party's lawyers will argue you waived your right to claim — even if the delay was entirely their fault and provably so.

Timing: the rule you cannot miss

Most contracts (FIDIC, NEC, LOGIC, bespoke EPC forms) require a notice within a defined period of the contractor becoming aware of the delay or its cause — typically 14–28 days. Some contracts make this a condition precedent to any EOT claim: miss the window, lose the entitlement, full stop.

The clock starts when a reasonable contractor should have known about the delay — not when the full impact became clear. A design change issued on Day 1 that only delays a critical activity in Month 4 still triggers the notice obligation on Day 1 if its critical-path impact was foreseeable.

When in doubt, notice it

If there's any doubt whether an event is delay-worthy, issue the notice. A precautionary notice that comes to nothing costs nothing. A missed notice on a real delay can cost the whole claim.

The five elements every notice needs

Different contracts use different language, but a defensible notice of delay contains five core elements. Missing any one of them gives the other party grounds to argue the notice was defective.

NOTICE OF DELAY · REF: CT2-NOD-0041
Notice of Delay — MEP Rough-in, Level 3
17 June 2026
Within 14-day window
1The delay event
Describe the specific event — not "delays to the works" but "late delivery of ductwork by owner-supplied vendor (EC1160), originally due 10 June 2026, not delivered as at date of this notice."
2The cause
Identify the contractual basis — owner-supplied materials, late approval, force majeure, variation. Link it explicitly to the relevant contract clause.
3The affected activities
Name the activities and their WBS codes. "EC1160 MEP Rough-in L3 (baseline start 10 Jun, currently blocked)" is defensible. "MEP works generally" is not.
4Estimated impact
State a preliminary estimate — even if imprecise. "Estimated impact: up to 14 days to project completion pending further analysis." Courts don't expect precision at notice stage; they do expect an attempt.
5Reservation of rights
"The Contractor reserves all rights to claim additional time and/or costs arising from this event and will provide full particulars in accordance with Clause X.X." This preserves entitlement while the analysis is completed.

The three mistakes that sink notices

1. Vague event description. "Delays to the works" with no specific event or activity will be rejected as too general. Every notice must identify a specific causal event that can be linked to a contractual entitlement.

2. Conflating the notice with the claim. A notice of delay is not a full extension-of-time claim. It's the trigger — the formal preservation of your right to claim. The full particulars (as-built impact, delay analysis, evidence package) come later. Don't delay issuing the notice because the analysis isn't finished.

3. Issuing to the wrong party or address. Most contracts specify who must receive the notice and how. An email to the site manager when the contract requires written notice to the employer's representative is technically defective.

A notice of delay is not a claim. It is the reservation that keeps the claim alive.

Automating the trigger

OPTEAM flags delay events at the moment they happen — when a field update records a blocked activity or a critical-path slip occurs. The system drafts the notice with the affected WBS codes, the event timestamp and a preliminary impact estimate, leaving the project controls team to review and issue rather than reconstruct from scratch under deadline pressure.

14–28d
Typical notice window in FIDIC/NEC contracts
5
Elements every defensible notice contains
Day 1
When the clock starts — awareness, not impact
The takeaways
  • The notice window starts when you should have known — not when the impact became clear.
  • When in doubt, issue a precautionary notice. A surplus notice costs nothing; a missed one can cost the claim.
  • Every notice needs: the event, the cause, the affected activities, an estimated impact and a rights reservation.
  • A notice is not a full claim — don't wait for the analysis to be complete before issuing it.

Draft delay notices from live project data.

OPTEAM flags the slip, identifies the affected activities and drafts the notice — while you still have time to issue it.

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