How long should project records be kept after completion?

The instinct to clear the file once a job is handed over and the final account is settled is the wrong one, because the period in which something can still come back to you usually runs long after the site has closed. How long depends on the contract and the law that governs it, but the shape is consistent: a claim for breach can generally be brought for a number of years after the breach, and that window is materially longer where the contract was executed as a deed than where it was a simple agreement, which is why the form of execution is worth knowing. On top of that sit the job's own tails: the rectification or defects period, during which defects must be made good and the second half of retention falls due; the durations of any collateral warranties, which can expose you to third-party claims for a long time; and any record-retention obligations the contract itself imposes. Keep the records that would matter if a claim arrived at the far end of that window, in a form that survives, which for records on people's phones and in personal folders means gathering them into one durable place before the team disperses. The records worth keeping prove what was built, how it was valued, what was instructed and what cover was in place: the diary, the photographs, the valuations and their measure, the correspondence, and the schedule of insurances, bonds and warranties. Storage is cheap; a defence you cannot mount because the file was cleared at handover is not.

Take a subcontractor who finished a JCT job executed as a deed, settled the account, and cleared the project folder within a year to free up space, keeping only the final account summary. Six years later a claim arrived alleging a defect in their work, comfortably inside the limitation window a deed carries, and the subcontractor could no longer produce the site diary, the progress photographs or the correspondence that would have shown the work was built to instruction and inspected. The defence became far harder than it needed to be, not because the work was bad but because the proof of it had been thrown away while a claim was still legally possible. The preventing habit costs almost nothing: at completion the whole file, diary, photos, valuations, letters and the cover schedule, is gathered off phones and personal folders into one archive and kept until the limitation and warranty tail has run, so that if a claim ever arrives the record that answers it is still there.