How to write a site diary someone will thank you for in two years

Here's a test worth applying to every diary entry you'll ever write: will this mean anything to somebody reading it in two years, in a meeting room, with money on the table? Because that's who a site diary is actually for. Not the QS this week and not the file. It's for a reader you might not have met yet, sitting in a room you hope never gets booked, trying to work out what really happened on a Tuesday nobody else remembers.

Most diaries fail that test and they fail it politely. "Steelwork ongoing. Weather fair. No issues." Three lines like that will pass any audit and win you absolutely nothing when it matters, because when the argument comes nobody is asking whether steelwork was ongoing. They're asking which gang was where, what they got done, what stopped and for how long and on whose account. The diary that answers those questions gets written the same day in roughly the same number of minutes, it just answers them on purpose.

So what does the two-year reader actually need? They need the day pinned down in facts rather than impressions. Who was on site, by trade and by company, with numbers. What plant was there and, just as important, what plant stood idle and why, because standing time is one of the few things in a diary that converts straight into money and it evaporates completely if it isn't written down on the day. They need what was planned against what actually happened, with the reason for any gap, in plain words. They need anything anybody senior said on a walkaround written close to verbatim, with who said it and who else heard it, because the eternal site question is have we got that in writing and the diary is often the only place it ever gets written.

They also need the entry to be honest about nothing. A day where you looked at the instructions received and there were none is worth recording as exactly that, because there's a world of difference between no instructions today and nobody wrote it down. One is a fact you might need. The other is a hole somebody else will fill with their version. Same goes for writing late. If the entry for Tuesday got written on Friday, say so. An entry that admits it was written three days on is worth more than one pretending otherwise, because the first time a diary gets caught improving on the truth, every other page of it goes in the bin too.

And photos. Take them, but a photo without a note is half a photo. Where it was taken, what it shows and why it mattered that day. The date buried in the file does the rest of the work for you.

None of this takes longer than the useless version, which is the point most people miss. The difference between a diary that protects you and one that doesn't isn't effort, it's knowing what the two-year reader needs before you start writing. Ten minutes at the end of the shift, done on the day, in the boring specific words.

Somewhere down the line, somebody will sit in a room with your diary in front of them and either build a case on it or quietly set it aside. Which one they do was decided sometimes years earlier, at half four, by you.

Next in this strand: the allocation sheet, which is where the fine detail of who did what actually lives, and why it's a site tool rather than paperwork.