What records should a subcontractor keep to prove delay and disruption?

Each day, record who was where and what they worked on. Note anything that held the work up, such as no access or missing information. Log labour and plant, and date every photograph. Keep every instruction, change, application, notice, receipt, delivery ticket and off-hire note. Give each record a reference, keep a note of every correction, and link each piece of evidence to where it came from. Check your subcontract for the forms it requires, who must sign them and who they go to. Check it too for what triggers a notice, and for any rules on keeping records or holding them for a dispute. How long to keep records can turn on insurance and legal duties, so ask your solicitor rather than assume one period fits all. Keep the originals. Mark anything written up later, so it is never mistaken for a record made at the time. Review key events as they happen and check the whole set regularly. That regular check does not replace keeping on top of notices day to day.