A site diary is the daily record of what actually happened on a construction site: weather, labour and plant on site, work done and where, deliveries, delays and their causes, instructions received, visitors, inspections and health and safety events. It is the one document that captures the job as it was lived, day by day, rather than as anyone later remembers it.
A useful entry is specific. Weather means actual conditions and when they bit, not just “poor”. Labour means trades and numbers, ideally against the areas they worked. Plant means what was on site, what it did and what stood idle, and why. Progress means what was achieved and where, in terms someone off site could follow: gridlines, plots, levels, rooms. Delays need a cause, a duration and a note of what they stopped. Photographs turn all of it from assertion into evidence.
The diary’s value is evidential. Because entries are made on the day, they are contemporaneous evidence, which adjudicators, arbitrators and the courts give far more weight than accounts reconstructed from memory once a dispute exists. Extensions of time, loss and expense claims, daywork accounts and defect arguments are routinely decided by whose daily records are more complete and credible.
The contract makes the diary more valuable still. JCT contracts do not prescribe one, but the machinery they do contain (notices of delay, applications for loss and expense, valuation of variations) runs on exactly the information a diary holds. NEC contracts push harder: the early warning duty and the eight-week time bar on notifying compensation events reward the party who knows what is happening on the day it happens, not a month later. Many subcontracts, frameworks and clients of any size simply require a daily record outright, and a clerk of works will often keep a rival one.
The most common failure is not poor writing but non-existence. Diaries are kept thinly, in arrears or not at all, because they depend on the busiest person on site finding time at the end of the day. Entries written up on Friday for the whole week converge on “works progressing”, which proves nothing. Paper diaries get lost, damaged or left behind in site cabins when the job demobilises, which is exactly when they start to be needed.
A simple test of any diary is whether a stranger could reconstruct the day from it three years later: who was there, what they did, what arrived, what stopped and why. If the answer is yes, the diary will carry weight when it matters. If the answer is no, the gap will be filled by the other side’s version of events.
Construction Metric builds the site diary automatically from the WhatsApp group your site team already uses, so the record exists even on the days nobody had time to write one: see how it works.