Site Diary Compensation Events: How Your Daily Records Win (or Lose) NEC4 Claims

I've seen it too many times. A legitimate compensation event worth six figures, time-barred or undervalued because the site diary didn't contain the right detail at the right time. This page explains how to write diary entries that directly support your NEC4 commercial position, which clause references matter, and what to record on the day the event happens.

Why Site Diaries Are Your First Line of Evidence

Under NEC4, compensation events are assessed prospectively from the dividing date. But here's the thing most people miss: prospective doesn't mean you don't need records. You need records to establish what was happening before the event, what changed, and what the forecast impact looks like. Without that baseline, your quotation is just a number on a page.

The Project Manager will look at three things when assessing a compensation event quotation:

1. What was the situation before the event? Your diary establishes this baseline.
2. What actually changed? Your diary captures the disruption as it happened.
3. Is the forecast reasonable? Your diary provides the evidence that supports your assumptions.

If your diary is thin, generic, or weeks behind, you've handed the Project Manager every reason to reject your quotation or make their own assessment under clause 64.1. That's rarely in your favour.

The Eight-Week Clock Starts Ticking in Your Diary

Clause 61.3 is unforgiving. If the Contractor doesn't notify a compensation event within eight weeks of becoming aware of it, the entitlement is lost. Gone. Doesn't matter how strong the claim is.

So when does "awareness" start? This is where your site diary becomes critical. The diary is often the first document that records something unusual happening on site. A drawing change arrives. Unexpected ground conditions appear during excavation. Access is delayed by the Client's other contractor.

If your diary records "received revised drawing Rev P7" on 4 March 2025, that's your awareness date. You have until 29 April 2025 to notify. Miss it and no amount of excellent record-keeping afterwards will save you.

The problem I see constantly: site teams record the event in the diary but don't tell the commercial team. The QS finds out six weeks later when reviewing the diary backlog. By then, there's a fortnight to notify, investigate, and prepare a quotation. It's a scramble that usually produces weak submissions.

What Your Diary Must Record on Day One

When something happens on site that could be a compensation event, your diary entry that day needs to capture:

• What happened, in specific terms ("Client's drainage contractor blocked access to plot 14-18 from 07:00 to 14:30")
• Who was affected ("6 bricklayers and 2 labourers stood down for 4.5 hours; 1 telehandler idle")
• What was planned ("Planned activity: superstructure brickwork to plots 14-18 per Accepted Programme Rev 3")
• What instruction triggered it, if any ("Site Manager verbal instruction at 07:15 to redirect to plot 22; confirmed by email 09:30")
• Photos with timestamps showing the obstruction, condition, or impact

That's five things. Takes ten minutes to record properly. Saves tens of thousands in recovered entitlement.

Connecting Diary Entries to the 19 Compensation Event Categories

NEC4 clause 60.1 lists 19 categories of compensation events. Your diary entries need to map to these categories, even if you don't cite the clause number in the diary itself. The commercial team does the mapping later, but the raw material has to be there.

Here's what to include in your site diary to support the most common compensation event types:

This table isn't exhaustive, but it covers roughly 80% of the compensation events I've dealt with on NEC4 contracts. The point is this: if you know what the contract requires, you can train your site team to capture it. If you don't, you'll spend hours reconstructing events from memory and fragments.

Worked Example: Ground Conditions on a Highway Package

Scenario: On a £12M highways improvement package under NEC4 Option C, the earthworks team encounters rock at formation level on the A46 diversion route. The Site Information showed granular fill to 3m depth. Actual conditions: limestone bedrock at 1.2m, requiring breaker attachment and revised disposal strategy.

Day 1 (Monday 10 March 2025): Site diary records: "Excavation to formation level, chainage 450-520. Hit rock at 1.2m depth. Site Information (borehole BH-07) indicated granular fill to 3.0m. Machine operator switched to breaker attachment at 11:00. Progress reduced from planned 40m/day to approximately 12m/day. Photos ref: IMG_4401-4409. Supervisor notified Commercial Manager by phone at 11:30."

Day 1 (same day): Commercial Manager reviews diary entry, cross-references Site Information, confirms potential CE under clause 60.1(12). Issues early warning notification to Project Manager citing clause 15.1.

Day 2 (Tuesday 11 March 2025): Formal CE notification submitted under clause 61.3, referencing diary entry, photos, and Site Information comparison.

Outcome: The diary entry from Day 1 established awareness, triggered the early warning process, and gave the commercial team everything they needed to notify within 24 hours. The quotation was built on recorded production rates (12m/day actual vs 40m/day planned), with contemporaneous photos showing the rock encountered.

Contrast: On the same project, a similar ground condition at chainage 680-710 wasn't recorded until the weekly diary catch-up five days later. By then, the exact depth, production rates, and resource impact were estimates rather than records. The Project Manager challenged the quotation, and the final agreed value was 30% below the Contractor's assessment.

That 30% gap on the second event? Roughly £85,000 in unrecovered Defined Cost. The only difference between the two events was the quality of the Day 1 diary entry.

Five Diary Mistakes That Kill Compensation Event Claims

1. Writing the diary days or weeks late

Catch-up diaries are obvious. The detail is thinner, the times are approximate, and an adjudicator will give them less weight than contemporaneous records. If your team can't write diaries daily, you have a process problem that costs real money.

2. Recording activity without recording disruption

"Brickwork to Block A" is a record of what happened. It says nothing about what was supposed to happen, what prevented it, or what impact it had. The commercial value lives in the gap between plan and reality. Record both.

3. Not linking diary entries to the Accepted Programme

Your diary should reference the Accepted Programme activity being undertaken. "Brickwork to Block A per Activity 4.2.1, Accepted Programme Rev 3" takes five extra seconds and directly connects the diary to the programme baseline that your CE quotation will reference.

4. Forgetting to record Client-side failures

When the Client's designer is late with information, or the Client's other contractor blocks your access, your team needs to record it that day. Not as a complaint, but as a factual record: what was due, when, and what the impact was. These are some of the most common compensation events, and they're the easiest to miss because the site team doesn't always see them as "events."

5. Treating photos as optional

A photo with a timestamp is worth more than a paragraph of description. Get into the habit of photographing conditions, obstructions, weather impact, and anything unusual. Label them. Store them against the diary entry. When the Project Manager queries your quotation six weeks later, the photo settles the argument.

The Records and Compliance Connection

Under NEC4 Option C and Option E, there's a second reason your diary matters: Disallowed Cost. Clause 11.2(26) defines Disallowed Cost as cost not justified by the Contractor's accounts and records. If you can't demonstrate that resources were on site, doing what you say they were doing, when you say they were doing it, the Project Manager can disallow the cost.

Your site diary, supported by daily allocation sheets, provides the resource-level evidence. Labour, plant, materials. Who was where, doing what, for how long. Without this, you're asking the Project Manager to take your word for it. Under a target cost contract, they won't.

The same records that protect your compensation event claims also protect your Defined Cost recovery. One diary entry serves both purposes.

Building a Diary System That Supports Commercial Outcomes

Good diary practice isn't about writing more. It's about writing the right things. Here's how to write a site diary that actively supports your commercial position:

Daily habit (10 minutes):

• Record planned vs actual activities, referencing the Accepted Programme
• Note any instruction, change, or obstruction from the Client or Project Manager
• Capture labour and plant on site by location and activity
• Photograph anything unusual

Weekly review (30 minutes):

• Commercial Manager reviews all diary entries against clause 60.1 categories
• Flag potential compensation events that site teams may not have recognised
• Cross-reference with correspondence and drawing registers
• Confirm all early warnings and CE notifications are issued where required

Monthly audit (1 hour):

• Check diary completeness using the completion checklist
• Verify all notified CEs have supporting diary evidence
• Identify gaps in recording and brief site teams
• Review retention and storage of diary records, photos, and allocation sheets

This isn't bureaucracy. On a £40M NEC4 project running for 18 months, I'd expect between 30 and 50 compensation events. At an average value of £60,000 each, that's between £1.8M and £3M in entitlement that depends on the quality of your site records. Ten minutes a day is cheap insurance.

How Gather Automates What You're Doing Manually

Everything on this page describes manual best practice. It works, but it relies on site teams recording the right things and commercial teams reviewing those records before the eight-week clock runs out.

Gather's QS AI Agent does this automatically. It reads every diary entry as it's written, compares it against clause 60.1 categories, and flags potential compensation events to the commercial team in real time. No more weekly catch-up reviews where you discover an event that's already five weeks old.

For teams managing multiple NEC4 packages, check our site diary examples to see what good contemporaneous records look like, or read about how AI is changing commercial management in construction.

Reference: Diary Evidence Requirements by CE Stage