CDM 2015 doesn't explicitly require a daily site diary. That's the technically accurate statement that some UK construction companies use to justify not keeping one. But trying to demonstrate that a site was managed safely and competently over a six-month project — without a contemporaneous record of what actually happened — is an exercise in hoping that nothing significant occurred and that memory is reliable.
Both of those things will eventually let you down.
What a daily log is actually for
The primary purpose of a site diary is to create a contemporaneous record. "Contemporaneous" matters legally — it means the record was made at the time, not reconstructed afterwards. When a dispute arises, or an incident is investigated by the HSE, or an inspector wants to know what was happening on a particular date, a log written that day carries far more weight than a statement prepared weeks later.
UK courts and HSE investigations both recognise the difference. A site manager who can refer to a specific daily log entry — "I noted the scaffold on grid line C needed the toe boards replacing, this was remedied before work started the following morning" — is in a materially better position than one who says "I think I noticed something around that time but I can't be certain of the exact date."
What a useful daily log contains
The level of detail matters. A daily log that says "works carried out, no issues" is almost worthless as evidence. Logs that hold up in challenging situations contain:
Date and weather conditions. Weather matters more than it seems — it's relevant to disputes about programme delays, decisions about working at height in high winds, why certain concreting works were halted. A weather record is also a simple data point that can be cross-checked against Met Office data if the record is real — or questioned if it isn't.
Workforce on site. Either a headcount or, better, a list of names by trade. If something happens on site and you can't account for who was present, you're dealing with a much harder problem.
Works carried out. Not just "groundworks" but a specific description of what phase, what location, what activities. This should reflect the current programme — if works are ahead of or behind programme, that's worth noting.
Plant on site. What plant was in use, operated by whom. For notifiable plant (cranes, MEWPs, excavators) the operator's certification details should be referenced. This matters for LOLER and PUWER compliance as well as for incident investigation.
Deliveries. What arrived, from whom, when. Delivery of hazardous materials, concrete pours, crane lifts — these are all worth recording. A concrete pour that causes a programme dispute is much easier to resolve with a contemporaneous log entry.
Visitors to site. Anyone who comes onto the site — clients, consultants, utility representatives, subcontractor management — should be logged. This becomes relevant if anyone later claims they weren't present for a particular discussion or instruction.
Issues and near misses. Anything that warranted attention: a near miss that was dealt with before it became an incident, a welfare facility that needed attention, a subcontractor working outside their agreed method statement. A log with no issues ever recorded, across a six-month project, doesn't look like a well-managed site — it looks like a log that isn't being used properly.
Photos as part of the log
A photo taken on site and stored with a timestamp is worth considerably more than a written description. Photos of completed lifts, excavation depths, formwork before a pour, scaffold board condition, welfare facilities — these provide a level of evidence that words can't replicate and close off certain classes of dispute entirely.
The problem with photos is that they need to be organised to be useful. Photos sitting in someone's phone camera roll, labelled "IMG_4782.jpg", from a date that's been overwritten by the phone's clock being wrong, are not evidence. They're noise.
The paper log problem
Paper site diaries have some genuine advantages — they require no technology and feel familiar. They also have significant practical limitations for any project where records need to be retrieved quickly.
Paper logs go missing. They get wet. The writing is illegible. They don't capture photos alongside the text entry. They can't be searched. When you're trying to find the log entry from a specific date four months ago because a dispute has arisen, flicking through a physical book that may or may not be in the site office is not a good use of time — and "I can't find it" is not a useful answer during an HSE inspection.
Digital logs are searchable, backed up, and accessible from anywhere. They can attach photos directly to an entry, with GPS coordinates and timestamps embedded in the image data.
Making it a habit
The biggest barrier to good daily logs isn't understanding why they matter — it's making the completion process quick enough that it actually happens every day. A site manager who has to find the site diary book, write several paragraphs in legible handwriting at the end of a long day, and then file it somewhere it won't get lost, will sometimes not do it. A site manager who can open a mobile app, fill in a structured form in three minutes, take a couple of photos, and be done — probably will.
Good daily log practice is also a core component of any solid CDM compliance audit pack. A continuous, contemporaneous record of site activity is one of the most powerful things you can produce when a client or regulator asks for evidence.
Lasso's daily log form is built for exactly this workflow: structured fields for all the key information, photo capture with automatic attachment, and a GPS-stamped record that's immediately backed up and searchable from the office. All of it feeds directly into the project audit trail.
Sign up for Lasso — see how long the first daily log actually takes.
Frequently asked questions
Are construction site diaries a legal requirement in the UK?
CDM 2015 does not explicitly mandate a daily site diary, but requires principal contractors to plan, manage, monitor, and coordinate the construction phase. Demonstrating this without a contemporaneous daily record is extremely difficult during HSE inspections or civil disputes.
What should a UK construction site diary contain?
At minimum: date and weather, workforce on site by name or headcount, works carried out, plant in use and operators, deliveries, visitors, and any issues or near misses. Photos with GPS timestamps add significant evidential value.
How long should construction site records be kept in the UK?
All project documentation should be retained for a minimum of six years in line with limitation periods under the Limitation Act 1980. RIDDOR records must be kept for at least three years. CDM Health and Safety Files should be kept for the life of the structure.
Can a retrospective site diary be used as evidence in the UK?
Retrospective logs carry significantly less weight in UK legal proceedings and HSE investigations. Courts and inspectors recognise them by their overly consistent writing and thin detail. A record written on the day is far more defensible.