I've reviewed thousands of diary entries across NEC3 and NEC4 contracts. The gap between a £400,000 recovery and a time-barred write-off? It often comes down to three or four sentences a site engineer couldn't be bothered writing at the end of a long shift. These examples are composites drawn from live projects, sanitised but realistic.
Want the theory first? Read how to write a site diary. Want to see what good and bad actually look like? Keep reading.
What Makes a Site Diary Entry Commercially Valuable?
Before the examples, here's the framework. A commercially valuable diary entry does three things:
- Records facts with enough specificity to reconstruct the day six months later
- Captures causation so you can link events to their consequences
- Creates a paper trail that supports or defends a compensation event, delay claim, or final account negotiation
That's it. You don't need to write a novel. Facts, times, names, consequences. Let's look at five scenarios.
Example 1: A Good Entry (Commercially Aware, NEC4 Compliant)
Here's what a strong entry looks like on a £28M highways resurfacing package under NEC4 Option C.
Date: Tuesday 11 March 2025
Weather: Overcast, 8C, dry. Wind NW 12mph. Suitable for all planned activities.
Labour on site: 14 operatives (Contractor), 6 operatives (Murphy Surfacing, subcontractor). Agency labour: 2 banksmen (Kelly Plant).
Plant and equipment: 2x CAT 320 excavators, 1x Wirtgen W210Fi cold planer, 3x 8-wheel tippers (Smith Haulage). Planer arrived at 07:45, 35 minutes late due to traffic management setup delay on A556 diversion.
Work completed:
- Planing of carriageway CH2450 to CH2780 (330m), average depth 50mm. Completed by 14:30.
- Base course laying CH2200 to CH2450 (250m), 100mm HRA. Rolling and compaction complete by 16:00. Core samples taken at CH2280 and CH2400.
Delays and disruptions:
- Cold planer start delayed 35 mins. TM contractor (Chevron) had not completed lane closures by 07:00 as programmed. Chevron's site supervisor (Mark Bentley) confirmed TM vehicle broke down en route. Planing gang stood idle 07:10 to 07:45. 14 operatives x 35 mins = 8.2 labour hours lost.
- Discussed with Project Manager (Sarah Cole) at 08:15. Verbal agreement this may constitute a compensation event under clause 60.1(5) if TM is a Client-provided service. PM requested written notification.
Visitors: Sarah Cole (PM) 08:00-12:00. HSE Inspector (Dave Thornton, CITB) 10:30-11:45, no issues raised.
Instructions received: None.
Safety: Toolbox talk delivered at 06:45 (topic: working near live traffic). Near miss reported at 11:20: tipper reversed within 2m of operative on foot. Reported to site manager. Banksman repositioned.
Photos: 6 photos taken. Planer delay (2), base course laying (2), near miss location (1), core sample locations (1). Uploaded to project folder.
Why This Entry Works
| Element | What's Done Well | Commercial Impact |
|---|---|---|
| Weather recorded with specifics | Temperature, wind, suitability statement | Defends against "you could have worked" arguments |
| Labour breakdown by employer | Separates contractor, subcontractor, agency | Supports Defined Cost records for Option C |
| Chainage references | Start/end points, depth, material type | Proves what was actually done vs programme |
| Delay quantified in labour hours | 14 people x 35 minutes = 8.2 hours | Immediate input for CE quotation |
| Causation chain documented | TM vehicle broke down, Chevron confirmed, delay to planer start | Establishes Client liability if TM is Client-provided |
| PM conversation recorded | Name, time, verbal agreement, request for written notification | Contemporaneous record of PM's initial response |
| Near miss documented with action | Location, time, corrective action taken | HSE compliance, defence against future claims |
| Photos referenced with subject | Not just "photos taken" but what they show | Corroborates written record |
The single most important feature? Causation. This entry doesn't just say "delay." It traces TM vehicle breakdown to Chevron to lane closure delay to planer standing time to lost labour hours. Six months later, when you're sat across the table negotiating the CE, this entry does the heavy lifting. Everything else is supporting detail.
Example 2: A Bad Entry (Vague, Commercially Useless)
Same project, different engineer. I see this kind of entry on roughly 60% of the site diaries I review. It's depressingly common.
Date: Wednesday 12 March 2025
Weather: Cold and overcast.
Work done: Continued surfacing works on the A556. Some delays due to weather in the afternoon. Subcontractors on site. Plant working as normal.
Issues: Had a problem with material delivery. Sorted by lunchtime.
Visitors: PM visited.
What's Wrong With This Entry
| Problem | What's Missing | Commercial Cost |
|---|---|---|
| "Cold and overcast" | No temperature, no wind speed, no suitability statement | Can't prove or disprove weather as a CE trigger under clause 60.1(13) |
| "Continued surfacing works" | No chainage, no quantities, no material specification | Can't prove progress against programme. Can't defend against allegations of slow working |
| "Some delays due to weather" | Which weather event? What time? How long? Who was affected? | Worthless for a time or cost claim. "Some delays" isn't evidence |
| "Subcontractors on site" | Which subcontractors? How many operatives? Doing what? | Can't verify Defined Cost. Can't allocate delay responsibility |
| "Problem with material delivery" | Which material? Which supplier? What time did it arrive? What was programmed? | Potential CE under 60.1(5) if Client-provided, but no evidence to pursue it |
| "Sorted by lunchtime" | Sorted how? By whom? Was there a cost? | No record of mitigation, no quantified impact |
| "PM visited" | Who specifically? What time? What was discussed? | Lost opportunity to record instructions or conversations that could support a CE |
I've seen this exact pattern cost a Tier 1 contractor over £180,000 on a single project. They had a legitimate sequence of weather delays across three weeks, but the diary entries were so vague they couldn't demonstrate duration, impact, or the link between the weather and the disruption to planned activities. The Project Manager's assessment under clause 64.1 was a fraction of the actual cost because there simply wasn't enough evidence to support a higher figure.
The fix isn't writing more. It's writing specifically. Compare "some delays due to weather" with "rainfall from 13:15. Planing suspended at 13:30 (surface too wet for HRA laying). 8 operatives stood down at 14:00. Resumed at 15:45 after surface dried. 2.25 hours lost." That takes 30 seconds longer to write and it's worth thousands.
Example 3: Weather Delay Entry With NEC4 CE Implications
Weather claims fail more often than any other CE category. Why? Because site teams don't record the right data on the day it happens. Under NEC4, weather is only compensable if it's measured at a stated place and shown to occur less than once in ten years. That's a specific test, and you need specific records to pass it.
Here's how to record a weather event that may trigger a compensation event under clause 60.1(13).
Date: Thursday 27 November 2025
Weather: Heavy and persistent rainfall from 06:00. Met Office Filton (nearest weather station to site, as stated in Contract Data Part One) recorded 28.4mm by 18:00. Wind SSW gusting 45mph. Temperature 4C.
Weather comparison: November 10-year average rainfall at Filton is 94.3mm (Met Office 2015-2024 data). Month-to-date rainfall as of 27 Nov: 142.7mm. This is approximately 151% of the 10-year monthly average.
Impact on planned works:
- Pile cap excavation (Plot 14-18) suspended at 07:30. Standing water in excavations exceeding 150mm. Dewatering pumps deployed but inflow exceeded pump capacity (2x 50mm submersible pumps, combined 600 l/min).
- Piling rig (Liebherr LB28) stood down for the day. Rig cannot operate safely on waterlogged ground (bearing capacity concern flagged by piling foreman, Jim Aldridge). Piling subcontractor (Cementation Skanska) demobilised 4 operatives at 09:00.
- Structural steel erection (Bay 3-4) suspended at 08:00 due to wind speed exceeding 40mph safe working limit per method statement MS-027.
Labour on site: 22 operatives arrived. 14 stood down by 09:30. 8 retained for site maintenance, dewatering, and welfare duties.
Programme impact: Piling to Plots 14-18 is on the critical path (Accepted Programme Rev C, Activity 4.2.3). One day lost today. If weather continues tomorrow, cumulative delay will exceed the 1-day float available before structural steel erection to Bay 5-6 is affected.
Actions taken:
- Early warning notified to PM (Sarah Cole) at 08:30 per clause 15.1, referencing risk of cumulative weather delay to piling critical path.
- Compensation event notification drafted for submission under clause 61.3. Weather data to be compiled at month end for formal 1-in-10-year comparison.
- Dewatering plan to be reviewed with site manager (Tony Reeves) tomorrow AM.
Photos: 8 photos. Standing water in excavations (3), piling rig stood down (2), rain gauge readings (2), wind speed display (1). All timestamped.
Annotation: What Makes This Entry Powerful
Most weather delay records I've reviewed are useless. They say "rained all day, no work done" and leave it at that. This entry does something different: it connects the weather data to a specific contractual mechanism.
The 1-in-10-year test. Under NEC4 clause 60.1(13), weather is only a compensation event if conditions at the weather station stated in Contract Data are shown to occur, on average, less than once in ten years. This entry records the actual rainfall (28.4mm on the day), references the correct weather station (Filton, as stated in the Contract Data), and provides the comparison baseline (10-year average for November). That's three things most entries miss entirely.
Critical path awareness. Noting that piling is on the critical path with reference to the specific programme activity (Rev C, Activity 4.2.3) makes it almost impossible for a PM to argue the weather had no time impact. Without this, the PM could simply say "you had float."
Early warning recorded. The entry proves the early warning was given the same day, with the clause reference and the PM's name. If this escalates to a dispute, the Contractor's compliance with clause 15.1 is documented.
Safe working limits referenced. Citing the specific method statement (MS-027) and the 40mph wind threshold turns a subjective "too windy to work" into an objective, auditable decision.
Example 4: Subcontractor Issue Entry
Subcontractor performance problems cause more programme slippage than weather, design changes, and ground conditions combined on most projects I've worked on. And yet they're consistently the worst-recorded events in site diaries. This example shows how to get it right, from a £45M water treatment works under NEC4 Option A.
Date: Monday 3 February 2025
Weather: Clear, 2C, frost until 09:00. All works commenced as planned after ground thaw.
Subcontractor issue: Mechanical installation (AquaTech Engineering)
AquaTech programmed to have 8 fitters on site today for pipe spool installation in Filter House 2 (Programme Rev D, Activity 6.3.1). Actual attendance: 3 fitters. AquaTech site foreman (Steve Marsden) confirmed 5 fitters redeployed to another contract without prior notice to us.
Impact:
- Pipe spool installation rate today: 4 spools (against programme of 12). Shortfall: 8 spools.
- Cumulative shortfall this week: 14 spools (Mon-Fri programmed: 60. Achieved to date: 46).
- Filter House 2 mechanical completion is now 6 working days behind the Accepted Programme (Rev D).
- Electrical first fix (following trade) cannot start in Zones 2A-2C until pipe spools complete. Electrical subcontractor (Derry Electrical) has 6 electricians on standby from Wednesday. If pipe spools aren't complete by Wednesday, Derry will incur standing time or demobilise.
Actions taken:
- Formal letter issued to AquaTech (ref: ATK/SD/2025-034) requiring recovery programme within 5 working days per subcontract clause 4.7.
- Discussed with AquaTech contracts manager (Louise Hewitt) by phone at 14:30. She confirmed additional fitters would be sourced by Wednesday. No written confirmation received.
- Following trade impact notified to PM (verbal, 15:00). PM acknowledged knock-on risk to commissioning programme.
- Updated 3-week lookahead to reflect revised pipe spool completion date of 14 Feb (was 6 Feb).
Other works completed:
- Civil works to Sludge Holding Tank 3: formwork to base slab complete. Pour scheduled Thursday 6 Feb subject to concrete delivery confirmation.
- MEICA contractor (Sulzer) continued pump installation in Inlet Works. 2 of 4 duty pumps installed and aligned.
Labour on site: Contractor: 18. AquaTech: 3 (should be 8). Derry Electrical: 4. Sulzer: 5. Total: 30.
Photos: 4 photos. Pipe spool progress in Filter House 2 (2), formwork to SHT3 (1), pump installation Inlet Works (1).
Annotation: What Makes This Entry Effective
Quantified shortfall, not just a complaint. "3 fitters instead of 8" is a fact. "AquaTech are underperforming" is an opinion. The entry gives both the attendance figure and the programme reference so anyone reading it can verify the gap.
Knock-on effects traced. The entry doesn't stop at "pipe spools are behind." It traces the impact forward to the electrical first fix, then to Derry's standing time risk. This is the kind of causation chain that wins final account negotiations.
Formal correspondence referenced. Citing the letter reference (ATK/SD/2025-034) ties the diary to the contractual paper trail. If this goes to adjudication, the adjudicator can see the letter was issued the same day the shortfall was recorded.
Phone conversation logged. Louise Hewitt's verbal commitment to provide additional fitters is recorded with her name, the time, and the caveat that no written confirmation was received. That last detail matters. It shows the Contractor was diligent and aware that verbal promises aren't enough.
Example 5: Plant and Equipment Breakdown Entry
Plant breakdowns happen every week on major earthworks projects. Recording them properly? That's rare. This example is from a £62M earthworks package on a rail embankment project under NEC4 Option C.
Date: Friday 16 May 2025
Weather: Dry, 18C, light breeze. Ideal earthworks conditions.
Plant breakdown: Volvo A40G articulated dump truck (Fleet No. EW-047)
Hydraulic failure on EW-047 at 09:40. Truck was hauling fill material from Borrow Pit 2 to Embankment Section E4 (CH38+200 to CH38+600). Hydraulic hose burst on rear axle steering circuit. Truck immobilised on haul road between BP2 and E4, blocking the single-track section for 55 minutes.
Immediate impact (09:40-10:35):
- Haul road blocked. 4 other A40G trucks queued behind. No alternative haul route available.
- Fill placement rate at E4 dropped to zero for 55 minutes.
- D9 dozer and 2x CAT CP563 rollers at E4 stood idle (3 machines, 3 operators, 55 mins).
Recovery and workaround (10:35 onwards):
- Broken truck towed to laydown area by D6 dozer at 10:35. Haul road reopened.
- Hydraulic hose replaced by fitter (our own, Dave Parsons) from site workshop. Truck returned to service at 14:20. Total downtime: 4 hours 40 minutes.
Production impact:
- Programmed fill placement today: 1,800m3 (based on 5 trucks x 12 loads/day x 30m3/load).
- Actual fill placement: 1,240m3. Shortfall: 560m3.
- Embankment E4 fill quantity to date: 34,600m3 of 52,000m3 target (66.5%).
- Today's shortfall will be recovered by Saturday working if approved. Recovery request submitted to PM at 15:00.
Cost record (for Defined Cost under Option C):
- Truck EW-047 downtime: 4h 40m. Operator (agency, Randstad): £38/hr fully loaded = £177.
- 4x queued trucks and operators idle 55 mins: 4 x (55/60) x £85/hr = £312.
- D9 + 2x CP563 rollers idle 55 mins: 3 x (55/60) x £95/hr = £261.
- Fitter time (2.5 hrs including travel to/from workshop): £42/hr = £105.
- Hydraulic hose and fittings: £340 (from site stock, to be reordered).
- Total recorded cost of breakdown: £1,195.
Root cause: Hydraulic hose age. EW-047 was due for hose replacement at next scheduled service (2,000-hour interval, currently at 1,847 hours). Hose failed 153 hours early. Not a maintenance failure; premature wear likely due to abrasive conditions at Borrow Pit 2.
Photos: 5 photos. Failed hose (2), truck location on haul road (1), queue of trucks behind (1), repaired hose assembly (1). All timestamped.
Annotation: What Makes This Entry Stand Out
Full cost breakdown. On an Option C contract, Defined Cost is everything. This entry doesn't just say "truck broke down." It records every machine, every operator, every hour, and every pound. When the next payment application lands on the PM's desk, these figures feed directly into the Defined Cost schedule. No guesswork. No arguments.
I've seen Option C projects lose tens of thousands in disallowed cost simply because nobody recorded plant standing time with enough detail. The Project Manager's quantity surveyor looks at the application, sees a lump sum for "plant downtime," asks for backup, and gets told "we'll have to work it out from timesheets." By then, the timesheets have been archived, the operators have moved to another site, and the cost gets disallowed.
Root cause analysis. Noting the hose hours and scheduled service interval proves this wasn't a maintenance failure. That matters more than you'd think. On Option C, the Project Manager can disallow costs resulting from the Contractor's failure to maintain plant properly. Without this detail, you're inviting a disallowed cost argument you'll probably lose.
Recovery plan documented. Requesting Saturday working and noting the recovery pathway shows the Contractor is mitigating the delay. Under NEC4, there's an obligation to mitigate (clause 16.1 for early warnings, general duty under the contract). Recording the mitigation step in the diary strengthens the Contractor's position.
Quick Reference: What Every Entry Needs
Use this as a mental checklist before you close out each day's diary. If you can't tick every row, your entry isn't complete enough.
| Element | Minimum Standard | Why It Matters |
|---|---|---|
| Date and shift times | Start/finish to the minute | Baseline for all time records |
| Weather | Temperature, precipitation, wind, suitability statement | CE trigger under 60.1(13); defence against "you could have worked" |
| Labour | Numbers by employer, names of key personnel | Defined Cost evidence (Option C/D); delay responsibility |
| Plant and equipment | Fleet numbers, arrival/departure times, breakdowns | Defined Cost; programme evidence; maintenance defence |
| Work completed | Chainage/location, quantities, materials, specifications | Progress vs programme; quality evidence |
| Delays and disruptions | Start/end time, cause, impact in hours/cost, who was affected | CE quotation input; delay analysis |
| Causation | What caused what, and the chain of consequences | The single most valuable element. Links facts to claims |
| Instructions | Who gave them, when, exact wording | Potential CEs under 60.1(1); change management |
| Conversations | Who, when, what was said, any commitments | Contemporaneous record; supports oral agreements |
| Photos | Numbered, captioned, timestamped, uploaded | Corroborates written record; invaluable in disputes |
| Safety | Incidents, near misses, toolbox talks, corrective actions | Legal compliance; CDM defence; duty of care |
Common Mistakes in Site Diary Entries
I see the same mistakes on almost every project I review. The good news? They're all easy to fix once you know what to look for.
- Writing "as planned" instead of recording what actually happened. If everything went to plan, say what was done, the quantities, and the completion time. "As planned" tells a reviewer nothing. It's also suspicious in a dispute because no day goes exactly to plan.
- Recording delays without quantifying them. "Some delays due to weather" is not evidence. "Rainfall 13:15-15:30, planing suspended, 8 operatives stood down, 2.25 hours lost" is evidence. Always record start time, end time, number of people affected, and hours lost.
- Forgetting to name people. "Discussed with the PM" is weak. "Discussed with Sarah Cole (PM) at 14:30" is strong. Names and times make diary entries credible. They also make them verifiable, which is why they hold up in adjudication.
- Ignoring subcontractor attendance. You can't claim delay responsibility sits with a subcontractor if you didn't record their attendance. Write down which subcontractors were on site, how many operatives each had, and what they were doing. Every day.
- Not recording what didn't happen. If a concrete delivery was programmed for 08:00 and didn't arrive until 11:30, that's a diary entry. If the PM was supposed to provide access to a work area and didn't, that's a diary entry. Absence of things is just as important as presence.
- Leaving the diary until the end of the week. Memory deteriorates fast. By Friday, you can't reliably reconstruct Tuesday's timeline. Write the entry on the day, ideally during the shift. This is where tools like Gather help: the app prompts you in real time, so nothing gets forgotten. And if you want a pre-built starting point, the site diary template and site diary completion checklist give you the structure before you even open the diary.
How Gather Helps You Write Better Entries
Now you know what good looks like. But here's the honest challenge: writing entries this detailed every day, across every section of a live site, takes discipline that's brutal to maintain over a 78-week programme. Can you really expect a tired site engineer to write like Example 1 at 17:30 on a Friday in November?
Gather's AI-powered site diary solves this by prompting site engineers for the detail that matters commercially. Instead of a blank text box, the app asks structured questions: What plant was on site? What was the weather? Were there any delays? It then cross-references your entries against the Accepted Programme and flags gaps before submission.
For commercial teams, Gather's QS AI Agent automatically scans completed diary entries against NEC4 clause 60.1 compensation event categories. The kind of weather recording in Example 3, or the subcontractor shortfall in Example 4, would trigger an automatic alert to the commercial team: "Potential CE identified. Review and notify within 8 weeks per clause 61.3."
That's the difference between a site diary that sits in a folder and one that actively protects your commercial position. For a deeper look at what AI can do for site engineers on NEC4 projects, or to understand how a site diary compares to other daily records, the daily report vs site diary page covers the distinctions in detail.
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