Why most subcontractors lose their EOT claims.

JCT clause 2.27 requires written notice "forthwith" upon becoming aware of a Relevant Event. We see this missed on 60% of the projects we audit — and a missed notice is the single most common reason an otherwise valid EOT gets rejected, not on its merits, but on a procedural technicality.

The problem isn't that subcontractors don't know the rules. It's that the rules are far tighter than most realise, that the notice is owed on events that don't look like programme events at the time, and that the substantiation pack is almost always reconstructed at month 22 — when it should have been built at week one.

This is a working note for site PMs, commercial managers and chartered QSs running subcontract packages under JCT or bespoke contracts in the UK. We've grouped it into the six things we'd want every project to do differently — starting on Monday morning.

1 · The notice window is days, not weeks

"Forthwith" doesn't have a precise legal definition, but case law treats it as a matter of days, not weeks. The leading authorities — London Borough of Hounslow v Twickenham Garden Developments, City Inn v Shepherd Construction — both interpret similar notice clauses as requiring action within a short window from awareness, not from the formal recognition that a programme event has occurred.

In practice, this means an Early Warning Notice is due:

• Within 7 days of becoming aware of the event under most modern bespoke contracts
• "Forthwith" under JCT — which we treat as 7 working days, sometimes less
• Within 8 weeks of the event under NEC3/NEC4 contracts (clause 61.3) — after which the Compensation Event is time-barred entirely

If you're serving the notice at month-end with the application, you've already missed it. If you're drafting the EOT claim at month 24 with no EWN trail, the claim is largely dead on procedure — regardless of how strong the merits are.

The single most common reason an otherwise valid EOT gets rejected isn't the merits — it's the notice timing. — Project audit findings · 2024–26

2 · What JCT 2.27 actually requires

Under JCT D&B 2016 / 2024, clause 2.27 ("Notice of delay to progress") sets out the contractor's notice obligation. It applies whenever the regular progress of the Works is being or is likely to be delayed. The notice must contain — at minimum:

1. The material circumstances, including the cause or causes of the delay
2. An identification of any event the contractor considers to be a Relevant Event (under clause 2.29) or a Matter (under clause 4.21)
3. An estimate of the expected delay to completion of the Works or relevant Section
4. Notification of any material change in any of the above

What this clause does NOT require — and where most subcontractors trip up — is final, definitive figures. A clause 2.27 notice is an early warning, not a final EOT claim. The estimate of delay can (and should) be updated as the impact becomes clearer. The mistake we see most often is contractors waiting until they have the "right" answer before serving the notice — by which time the window has closed.

3 · The contemporary records problem

A notice without records is a complaint with a clause reference attached. Adjudicators, judges, and main-contractor commercial directors all look for the same thing when they read an EOT claim: did this happen the way the claim says it happened, and is there contemporaneous evidence to prove it?

"Contemporaneous" is the operative word. Records reconstructed three months after the event carry a fraction of the weight of records logged on the day. The five record types that decide EOT claims are:

• Daily site reports — completed and time-stamped by 18:00 the same day, never backfilled
• Photographs with location reference (plan grid, level, zone) and time-stamp metadata intact
• RFIs and their responses — particularly the gap between question and answer, which is often where the delay lives
• Architect's Instructions and Site Instructions — including verbal ones, written up the same day with sender acknowledgement
• Programme updates — baseline vs as-built, week-on-week, with delay events marked at the point they occurred

4 · How adjudicators apply the SCL Protocol

The Society of Construction Law's Delay & Disruption Protocol (2nd edition, 2017) is the methodology UK adjudicators and Technology and Construction Court judges apply when assessing delay claims. It's not legally binding — but it is overwhelmingly the standard.

The Protocol favours Time Impact Analysis (TIA) as the preferred methodology where the programme baseline is sound and the delay events can be identified discretely. Where TIA isn't feasible (e.g. multiple concurrent delays, incomplete programme), the Protocol allows for Time Slice Analysis or Windows Analysis as alternatives.

The implication for subcontractors: if your EOT submission isn't built using one of the SCL Protocol methodologies — with the right inputs (baseline, as-built, contemporaneous records) — the adjudicator's first move is to discount it. Not on merit. On methodology.

5 · Substantiation that survives adjudication

A defensible EOT submission contains five components, each tied to the SCL Protocol's expectations:

1. The baseline programme — agreed, signed off by both parties, with critical path identified
2. The notice trail — every EWN served, with date stamps and acknowledgement of receipt
3. The factual matrix — what happened, when, who knew, with contemporaneous records cross-referenced
4. The Time Impact Analysis — TIA showing the programme position immediately before and after each Relevant Event
5. The narrative — connecting the records to the analysis to the relief claimed, in plain language

This is also the structure that wins without going to adjudication. The main contractor's QS reads a submission built this way and recognises that an adjudicator would find for the subcontractor — and settles. We've prepared dozens of Scott Schedules using this structure that never had to be filed because the records spoke for themselves at the WP negotiation table.

6 · What to do this week

If you're running a project right now without a contemporaneous record system, four things to do this week:

1. Audit the last 30 days — pull every daily site report, RFI, AI, and photograph. Identify the gaps. You can't change history, but you can stop adding to the gap from today.
2. Deploy a daily site report template by Monday — completed and submitted by 18:00 each working day, every working day. This is the keystone document.
3. Set up an EWN tracker — a simple register of trigger event, date served, contract clause cited, expected impact, and main-contractor acknowledgement.
4. Sign off the baseline programme — formally, in writing — if it isn't already. Without an agreed baseline, even the cleanest TIA has nothing to compare against.

None of this is exotic. All of it is standard discipline. The reason it isn't done — on most of the projects we audit — isn't lack of capability, it's lack of bandwidth at the site team level. Which is why we exist. We sit in the chair where notice discipline lives, every day, on every project we run.

The best time to deploy a notice discipline was before the contract was signed. The second best time is this Monday morning.