This isn't about how to write well (that's covered in our how to write a site diary guide). This is about what goes in. Think of it as the checklist you hand to a site engineer on their first day and say "capture all of this, every day, no exceptions."
The 12 Essential Site Diary Fields
Before we go through each field in detail, here's the summary. Bookmark this table.
| # | Field | Why It Matters Commercially | What Happens If You Miss It |
|---|---|---|---|
| 1 | Date, shift times, and working hours | Establishes the factual timeline for delay analysis | Can't prove when work started or stopped |
| 2 | Weather conditions | Grounds weather-related delay claims under clause 60.1(13) | No baseline data to compare against 10-year averages |
| 3 | Labour and headcount | Proves resource deployment for disruption claims | Adjudicator has no evidence of actual manning levels |
| 4 | Plant and equipment | Supports standing time claims and Defined Cost records | Can't evidence idle plant costs |
| 5 | Materials delivered and used | Tracks Defined Cost and evidences waste from changed methods | No audit trail for cost reconciliation |
| 6 | Work completed and progress | Measures progress against the Accepted Programme | No baseline for delay or acceleration claims |
| 7 | Visitors and attendees | Records who was on site when instructions were given | Verbal instructions become deniable |
| 8 | Instructions received | Captures potential compensation events at the point they occur | Time bar clock runs while you've got no record |
| 9 | Delays and disruptions | Contemporaneous evidence for time and cost claims | Retrospective delay analysis without supporting records |
| 10 | Health and safety observations | Protects against CDM liability and evidences safe working | Regulatory exposure and weakened credibility |
| 11 | Photographs and visual records | Provides irrefutable evidence of site conditions | "He said, she said" arguments with no visual proof |
| 12 | Quality and inspections | Demonstrates compliance and records defect observations | Disputes over when defects were visible or reported |
That's your featured snippet. Now let's get into the detail.
1. Date, Shift Times, and Working Hours
This sounds obvious. It isn't. I've seen site diaries where the date is recorded but nobody noted whether it was a day shift or night shift, what time work actually started, or when the last operative left site.
What to record:
- Date (including day of week, because weekend working has commercial implications)
- Shift start and finish times
- Any overtime or extended hours
- Whether the day was a planned working day per the Accepted Programme
Why it matters under NEC4: Delay analysis under clause 63 requires you to demonstrate the impact on planned completion. If you can't prove which days were working days and what hours were worked, your time impact analysis falls apart. The adjudicator needs to see a clear timeline, not a vague reconstruction.
The commercial risk of missing it: On a highways scheme I worked on, the Contractor claimed 14 days of delay from a utilities diversion. The Project Manager's assessment was 8 days. The difference came down to whether Saturday working was planned or not. The diary didn't record it. The Contractor lost 6 days of entitlement worth approximately £180,000 in prolongation costs because nobody wrote down the shift pattern.
2. Weather Conditions
Weather is one of the most commonly claimed compensation events under NEC4, and one of the most commonly rejected. The reason? Poor records.
What to record:
- Temperature (morning and afternoon, minimum)
- Rainfall (estimated mm or simply light/moderate/heavy, with duration)
- Wind speed and conditions (calm, moderate, strong, gusting)
- Ground conditions resulting from weather (waterlogged, frozen, workable)
- Whether weather stopped or restricted work, and for how long
Why it matters under NEC4: Clause 60.1(13) provides for compensation events when weather conditions occur that are measured at the nearest weather station and are shown by comparison with weather data to occur on average less frequently than once in 10 years. You need contemporaneous records to cross-reference against the Met Office data. Recording "rain" isn't enough. You need duration and intensity.
The commercial risk of missing it: Without your own site weather records, you're entirely dependent on the nearest Met Office station, which might be 15 miles away in a sheltered valley while your site sits on an exposed hilltop. I've seen a £2.4M earthworks package where the Contractor had compelling Met Office data showing exceptional rainfall, but the Project Manager rejected the claim because the site diary just said "wet" for 6 consecutive days. No durations, no intensity, no record of which activities were affected. The CE was assessed at nil.
For more on weather-related claims, see our guide to NEC4 early warnings, because persistent adverse weather should trigger an early warning before it becomes a compensation event.
3. Labour and Headcount
Every person on site should be recorded. Not just your direct employees, but subcontractor operatives, agency staff, and any specialist labour.
What to record:
- Number of operatives by trade (not just a total headcount)
- Which subcontractor each gang belongs to
- Hours worked per trade
- Any labour standing time and the reason
- Absenteeism and the reason if known
Why it matters under NEC4: Disruption claims live or die on labour records. If a compensation event caused you to work inefficiently, you need to demonstrate the difference between planned and actual manning levels. Under clause 63.1, assessment is based on the effect on Defined Cost, and labour is typically the largest component of Defined Cost on a construction project.
Your daily allocation sheet captures the detailed breakdown, but the site diary should record the summary headcount as a cross-reference and audit trail.
The commercial risk of missing it: A Tier 1 contractor on a rail electrification project claimed £1.2M in disruption costs across 47 compensation events. They had excellent notification records and detailed quotations. But the Project Manager challenged the labour element because the site diary only recorded total headcount, not a trade-by-trade breakdown. The assessment was reduced by roughly 35% because the Contractor couldn't demonstrate which trades were disrupted by which events.
4. Plant and Equipment
Plant records serve two purposes: they evidence Defined Cost for compensation events, and they protect you when the Client queries standing time charges.
What to record:
- All plant on site (type, size, hire company)
- Hours worked per item of plant
- Any plant standing idle, with the reason
- Plant breakdowns and the cause
- Any plant brought to or removed from site
Why it matters under NEC4: Standing time for plant is a real cost, and it's part of Defined Cost under the Schedule of Cost Components. But you can only claim it if you can prove the plant was on site, was idle, and was idle because of a compensation event rather than your own planning failure. The diary entry is your first line of evidence.
The commercial risk of missing it: A 35-tonne excavator on a short-term hire costs roughly £1,200 per day. If a compensation event causes 3 weeks of standing time and you haven't recorded the plant as being on site and idle, that's £18,000 you can't evidence. Multiply that across a fleet of plant on a major project and you're looking at six-figure gaps in your cost records.
5. Materials Delivered and Used
Nobody gets excited about material records. But try substantiating a £340,000 cost change without them.
What to record:
- Materials delivered to site (type, quantity, supplier, delivery ticket reference)
- Materials used each day and on which activity
- Any materials rejected or returned, with the reason
- Wastage above normal levels and the cause
- Materials stored on site (important for interim valuations)
Why it matters under NEC4: When a compensation event changes the method of working, material quantities and types often change too. Your quotation under clause 62 needs to reflect the Defined Cost impact, and material records give you the audit trail. They're also critical at final account when reconciling actual versus forecast material costs.
The commercial risk of missing it: On a £28M water treatment works, a design change to the concrete specification increased material costs by £340,000 across the remaining works. The Contractor's CE quotation was well-prepared, but the Project Manager challenged the baseline quantities because the site diary had no record of daily concrete pours before the change. The assessment was delayed by 4 months while the team reconstructed records from batching plant tickets and delivery notes. Don't put yourself through that.
6. Work Completed and Progress
This is the heart of the diary. What actually got done today?
What to record:
- Activities started, in progress, and completed
- Location of work (specific, not vague: "Bay 3-4 Level 2 slab pour" not "structural work")
- Quantity of work completed (linear metres, cubic metres, number of units)
- Whether progress matched the programme or fell behind
- Any activities that couldn't start and the reason why
Why it matters under NEC4: Progress records are your evidence base for measuring delay against the Accepted Programme. Under clause 63.5, the assessment of delay to planned Completion is based on the impact on the programme. You can't demonstrate impact if you can't show what was actually achieved each day versus what was planned.
The commercial risk of missing it: A site diary that says "earthworks continued" tells an adjudicator nothing. Compare that to "Cut in Area C progressed from Ch. 450 to Ch. 520 (70 linear metres). Programme target was Ch. 580. Behind programme by 60m due to uncharted services encountered at Ch. 475." The second version gives you a contemporaneous record of delay cause and quantum. The first gives you a headache at final account.
For more on structuring progress records effectively, see our site diary examples page.
7. Visitors and Attendees
Every person who visits your site should be recorded. This isn't just about security. It's about commercial protection.
What to record:
- Name, organisation, and role of every visitor
- Time of arrival and departure
- Purpose of visit
- Any instructions, comments, or observations made during the visit
- Whether a site walk was conducted and which areas were inspected
Why it matters under NEC4: The Project Manager's site visits are commercially significant. If the PM walks the site, observes a condition, and says nothing, that silence can become relevant to a compensation event notification. Under clause 61.1, the Project Manager should notify the Contractor of compensation events. If they visited, saw an issue, and didn't notify, your visitor record proves their awareness.
Verbal instructions from the PM during a site visit are another critical capture. "Can you move that access road 5 metres east?" sounds casual. It's a compensation event. If it's not in your diary, it never happened.
The commercial risk of missing it: Verbal instructions are the single biggest source of unrecorded compensation events in UK construction. On one Network Rail project, the commercial team estimated they'd missed approximately £400,000 in legitimate CEs over 18 months, almost entirely from verbal PM instructions during site walks that nobody wrote down. The supervisors remembered the conversations. They couldn't prove them.
8. Instructions Received
Every instruction you receive on site, whether written, verbal, or implied by a change to drawings, should be captured in the diary.
What to record:
- Who gave the instruction (name, role, organisation)
- Exactly what was instructed (quote where possible)
- When it was given (date, time)
- How it was given (verbal, email, marked-up drawing, RFI response)
- Whether it changes the Works Information or the programme
- Your assessment of whether it constitutes a compensation event
Why it matters under NEC4: Under clause 60.1(1), the Project Manager giving an instruction that changes the Works Information is a compensation event. Under clause 61.3, you have 8 weeks from becoming aware to notify. That clock starts ticking the moment the instruction is given. If you don't record it in your diary, you might not recognise it as a CE until weeks later, and by then, you might be time-barred.
This is where the site diary connects directly to the eight-week time bar. Your diary is your early warning system for compensation events.
The commercial risk of missing it: Time-barred compensation events are unrecoverable. Full stop. The 8-week clock runs whether you're aware of it or not. A Tier 1 contractor on a highways scheme lost entitlement to 23 compensation events in a single year, totalling an estimated £1.8M, because site instructions were carried out but never recorded and therefore never notified. The work was done. The cost was real. The entitlement was gone.
9. Delays and Disruptions
Here's where most diaries fall apart. Everyone records that a delay happened. Almost nobody records why it happened, what it affected, or how long it lasted. That's the difference between a claim and a complaint.
What to record:
- What caused the delay or disruption
- When it started and when it ended (or if ongoing)
- Which activities were affected
- Whether it affected the critical path or had float
- What mitigation was attempted
- The estimated time and cost impact
Why it matters under NEC4: Delay records are the foundation of your time impact analysis. Under clause 63.5, assessments of delay are based on the effect on the Accepted Programme. Your diary entries create the contemporaneous narrative that supports (or undermines) your formal delay analysis. Adjudicators place significant weight on contemporaneous records over retrospective reconstructions.
If the delay or disruption could affect total cost or planned Completion, it should also trigger an early warning under clause 15.
The commercial risk of missing it: Retrospective delay analysis without contemporaneous records is expensive, time-consuming, and unconvincing. A claims consultant will charge you tens of thousands of pounds to reconstruct what happened, and the result will always be less credible than a site diary entry written on the day. I've sat in adjudications where the adjudicator asked the Contractor "What does your diary say about this delay?" and the answer was "We didn't record it." That's the moment you know you've lost.
10. Health and Safety Observations
Safety records protect people first. But they also protect your commercial position.
What to record:
- Any incidents, near misses, or accidents (with RIDDOR reference numbers if applicable)
- Safety briefings and toolbox talks held
- Hazards identified and actions taken
- PPE compliance observations
- Any stop-work orders and the reason
- Safety inspections by the principal contractor or client
Why it matters under NEC4: A stop-work order for safety reasons is a potential compensation event if it arises from something outside your control. Your safety records evidence when work stopped, why, and for how long. They also demonstrate that you were operating safely and in compliance with CDM 2015, which matters if the Client tries to argue that a delay was caused by your own unsafe practices.
Beyond NEC4, safety records are a legal requirement under CDM. The HSE doesn't care about your commercial position. They care about whether you managed risks properly. Your site diary is part of that evidence.
The commercial risk of missing it: A safety incident with incomplete records creates two problems simultaneously. First, regulatory exposure: the HSE will investigate, and gaps in your safety records look negligent. Second, commercial exposure: if the incident causes delay and you can't demonstrate it wasn't your fault, the cost sits with you. That's a double hit you can avoid by spending two minutes per shift recording safety observations.
11. Photographs and Visual Records
A photograph is worth a thousand words in a diary entry. It's worth considerably more in an adjudication.
What to record:
- Start-of-day and end-of-day progress photographs
- Before and after shots of any changed conditions
- Ground conditions, especially before excavation
- Existing condition surveys (critical before working near client assets)
- Any defects or damage observed
- Photograph metadata: date, time, location, direction facing, what it shows
Why it matters under NEC4: Photographs provide irrefutable evidence of site conditions at a point in time. When you're assessing a compensation event months later, a photograph showing waterlogged ground on the day work stopped is worth more than any amount of written narrative. Under clause 63.1, the assessment uses forecast Defined Cost from the dividing date onwards, so what was actually visible and documented on that date matters enormously. Photographs capture that reality in a way no written record can match.
The commercial risk of missing it: Arguments about site conditions are endemic in construction disputes. "The ground wasn't that bad." "The existing services weren't in that location." "The access road was usable." Without photographs, these become subjective debates. With photographs, they become matters of fact. I've seen a single photograph of a flooded excavation resolve a 6-month CE dispute in under an hour. The PM had argued the Contractor was exaggerating the condition. The photo showed 800mm of standing water. Discussion over.
For a practical template that covers all these photographic requirements, see our site diary template.
12. Quality and Inspections
Quality records are the ones most likely to be skipped. Don't skip them.
What to record:
- Inspections requested and completed (hold points, witness points)
- Test results (concrete cube results, compaction tests, weld inspections)
- Any work rejected or requiring remediation
- Defects observed and reported
- Sign-offs and approvals received
- Any Supervisor instructions or notifications under the contract
Why it matters under NEC4: The Supervisor plays a specific contractual role under NEC4. Their instructions and observations have commercial weight. If the Supervisor notifies a Defect under clause 44, you need a diary record of the condition at the time of notification, because the discussion about whether it's actually a Defect, when it arose, and who's responsible will happen later.
The commercial risk of missing it: Defect disputes often come down to timing. When was the defect visible? Was it present before or after a compensation event changed the Works Information? Your diary record of inspections and observations creates the timeline. Without it, you're relying on memory, and memories are unreliable at the best of times, let alone 12 months after the event.
Worked Example: One Day's Complete Diary Entry
Project: A55 Highway Improvements, Package 3
Contract: NEC4 ECC Option C, target cost £42M
Date: Tuesday 15 April 2025
Shift: 07:00 to 18:00 (day shift)Weather: Overcast, light rain 09:30-11:45 (approx 4mm). Temperature 8C morning, 11C afternoon. Moderate wind SW 15-20mph. Ground conditions soft in Area D following overnight rain, remainder workable.
Labour (58 total):
- Earthworks gang (SubCo A): 12 operatives, 8 hrs
- Drainage gang (SubCo B): 8 operatives, 8 hrs. 2 operatives standing 09:30-11:45 due to rain in open trench
- Structures team (direct): 14 operatives, 10.5 hrs (overtime approved)
- Steel fixers (SubCo C): 6 operatives, 8 hrs
- General labourers: 8 operatives, 8 hrs
- Supervision: 4 (site agent, 2 engineers, foreman)
- Traffic management: 6 operatives
Plant:
- 2x CAT 320 excavators (working, earthworks Area C)
- 1x CAT 320 excavator (standing 09:30-14:00, drainage Area D, soft ground)
- 3x 8-wheel tippers (working, muckaway)
- 1x 50T mobile crane (working, structures Bay 4-6)
- 1x concrete pump (standing 07:00-09:00, awaiting delivery, then working 09:00-16:30)
Materials:
- Ready-mix concrete: 45m3 delivered (Hanson, tickets #4521-4528), used for Bay 5 deck pour
- Rebar: 8T delivered (BRC, DN ref 2025-0891), stored compound
- Type 1 sub-base: 120T delivered, placed in Area C Ch. 620-680
Progress:
- Earthworks Area C: Cut progressed Ch. 600-680 (80 linear metres). Programme target 100m. Behind by 20m due to harder material than expected from Ch. 640 onwards. Potential CE: unforeseeable ground conditions, clause 60.1(12). Early warning raised EW-047.
- Drainage Area D: Trench excavation suspended 09:30-11:45 (rain in open trench, safety). Resumed and completed 35m of 450mm pipe installation. On programme.
- Structures Bay 5: Deck pour completed (45m3). Cube samples taken (ref CS-0415-01 to CS-0415-06). Pour commenced 09:15, completed 15:30. On programme.
- Structures Bay 4-6: Rebar fixing continued. 60% complete. On programme.
Visitors:
- Project Manager (J. Thompson, Client PM team) arrived 10:00, departed 12:30. Site walk of earthworks Area C and structures. Verbally instructed relocation of Site Compound welfare unit to accommodate revised access for Bay 7 works. Potential CE: PM instruction changing Works Information, clause 60.1(1). To be confirmed in writing. Diary record serves as contemporaneous note.
- HSE Inspector (M. Davies, HSE) arrived 13:00, departed 14:45. Routine inspection. No actions raised.
Instructions:
- PM verbal instruction re welfare unit relocation (see Visitors above). Site agent emailed PM at 13:15 requesting written confirmation. No response yet.
- Supervisor instruction SI-089: approved revised rebar detail for Bay 6 parapet (drawing revision C3 issued 14/04/2025).
Delays:
- Drainage Area D: 2.25 hours lost to rain. Not critical path activity, float consumed.
- Earthworks Area C: Harder material from Ch. 640 reducing output from 12m/hr to 6m/hr. Ongoing. If sustained, will affect critical path by estimated 5 days. Early warning EW-047 raised.
- Concrete pump standing 2 hours awaiting delivery. Supplier scheduling issue, not a CE.
Health and Safety:
- Toolbox talk: Manual handling (15 attendees, register attached)
- Near miss: Overhead cable strike risk identified during crane operations Bay 4. Banksman repositioned, exclusion zone extended. Recorded in near-miss register NM-2025-031.
Photographs: 18 photos taken (filed in project photo log, date-stamped). Including: earthworks face at Ch. 640 showing harder material (photos 7-9), completed Bay 5 deck pour (photos 12-14), ground conditions Area D (photos 15-16).
That's what a complete diary entry looks like. Every field captured. Every commercial trigger identified. Two potential compensation events flagged on the day they occurred, not reconstructed months later.
What Good Looks Like vs What Most Sites Actually Capture
Let's be honest. Most site diaries don't look like the example above. Here's the gap between what you should capture and what typically gets recorded.
| Field | What Good Looks Like | What Most Sites Capture | What Gets Lost |
|---|---|---|---|
| Weather | "Light rain 09:30-11:45, approx 4mm, ground soft in Area D" | "Overcast, some rain" | Duration, intensity, and ground impact |
| Labour | Trade-by-trade breakdown with hours and standing time | Total headcount: "58 on site" | Which trades were affected by which events |
| Plant | Individual items, hours worked, standing time with reasons | "Plant on site as previous" | Standing time evidence for CE claims |
| Progress | Location-specific with quantities and programme comparison | "Earthworks continued" | The actual measure of delay |
| Instructions | Who, what, when, how, and CE assessment | Not recorded unless written | Verbal instructions from PM site walks |
| Delays | Cause, duration, activities affected, mitigation, critical path impact | "Delays due to weather" | The mechanism linking cause to effect |
| Photos | Date/time stamped, captioned, filed systematically | Random phone photos in someone's camera roll | Retrievability when you need them 12 months later |
The difference between columns two and three is, conservatively, hundreds of thousands of pounds on a major project. On a £42M highway scheme, missing even 10% of legitimate compensation events represents over £100,000 in unrecovered entitlement. And 10% is optimistic. Most commercial teams estimate they miss 30-40% of CEs during the works, primarily because the diary records weren't detailed enough to identify them.
The Three Questions Every Diary Entry Should Answer
If you're short on time (and you always are on site), ask yourself three questions before you close the diary for the day:
1. "Could anything that happened today be a compensation event?"
If yes, record the details and flag it. The eight-week time bar starts from awareness. Your diary entry proves when you became aware.
2. "If I had to prove what happened today in an adjudication, would this entry be enough?"
If not, add the detail. Adjudicators want dates, times, quantities, causes, and effects. They don't want "work progressed as planned."
3. "Have I recorded everything the Project Manager or Supervisor said or did today?"
Every PM instruction is a potential CE. Every Supervisor observation is a potential Defect notification. Capture them all.
How Gather Captures These Fields Automatically
Recording 12 fields every day across multiple work fronts is a lot of manual effort. It's why most diaries end up incomplete despite everyone's best intentions. The site engineer is busy. The foreman has 40 operatives to manage. The diary gets filled in at 6pm from memory, and the detail suffers.
Gather's AI-powered site diary is built around these 12 fields. Site teams capture data through structured mobile forms that prompt for each field, so nothing gets missed. The AI agent then reviews every entry against the contract terms and project programme, flagging potential compensation events, early warnings, and gaps in the record before they become problems.
The result: complete records captured in real time, not reconstructed from memory. On projects using Gather, commercial teams report identifying 40% more compensation events during the works, primarily because the diary prompts captured information that would otherwise have been missed.
See how it works for your next project. Book a demo.
Your Site Diary Completeness Checklist
Use this as a daily check. Print it, laminate it, stick it on the site office wall. If you can tick every box, your diary is doing its job. If you can't, you've got a gap that will cost you later. For a more comprehensive end-of-project version, see our completion checklist.
| # | Field | Captured Today? |
|---|---|---|
| 1 | Date, shift times, working hours | [ ] |
| 2 | Weather: temperature, rainfall (duration + intensity), wind, ground conditions | [ ] |
| 3 | Labour: headcount by trade, hours, standing time | [ ] |
| 4 | Plant: items on site, hours worked, standing time with reasons | [ ] |
| 5 | Materials: deliveries, quantities used, wastage | [ ] |
| 6 | Progress: activities, locations, quantities, programme comparison | [ ] |
| 7 | Visitors: name, org, purpose, any instructions given | [ ] |
| 8 | Instructions: who, what, when, CE assessment | [ ] |
| 9 | Delays: cause, duration, activities affected, critical path impact | [ ] |
| 10 | Health and safety: incidents, briefings, hazards, actions | [ ] |
| 11 | Photographs: progress, conditions, before/after, captioned | [ ] |
| 12 | Quality: inspections, test results, defects, sign-offs | [ ] |
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