Mechanical and electrical contractors sit at the end of the sequence and inherit whatever the programme has done on the way there. Compressed installation windows, piecemeal access, working around trades that should have finished: the money you lose to disruption rarely comes from one dramatic event. It comes from a hundred half-days, each one explainable at the time and forgotten by the final account.
The claims literature is blunt about disruption: it is one of the hardest heads of claim to prove, and it fails on records more than on merit. To recover the cost of working out of sequence you need contemporaneous evidence of what access you were given and when, what conditions you found, what your crews actually did, and how that differed from what was planned. Reconstructing that from memory months later is exactly what tribunals discount.
Your supervisors already generate the evidence. The riser photo before and after. The message that ceiling grid on level three is still not closed. The voice note about the plantroom being used as storage again. Construction Metric captures that stream from the project WhatsApp group, with consent, and builds it into a structured daily record: areas worked, labour deployed, access received or refused, delays with causes, tests and inspections, photographs in context.
Because entries are timestamped and attributable as they happen, the record does what a claim needs it to do: it shows the pattern. Not one blocked work front but the same work front blocked eleven times in six weeks, with photographs. Not a vague assertion of disruption but a day-by-day account of gangs redeployed and sequences broken. That is the difference between a number your QS can defend and a number that gets negotiated away.
The record also serves the quality side of M&E. Test results, inspection sign-offs and closure photos land in the same searchable record, aligned to an ISO 19650 structure, so handover documentation stops being an end-of-job archaeology exercise.
M&E contractors typically get five to eight hours per site per week back from supervision, and something harder to price: a disruption case that writes itself as the job happens. When the conversation about prolongation and loss of productivity finally arrives, you are the party with the diary.