The disruption is real and we can't put a number on it
We know the sequence was wrecked. Turning that into measured productivity loss is the part that keeps failing.
What's happening?
Everyone who was on the job tells the same story: trades stacked on top of each other, work out of sequence, the same areas visited three times. Nobody disputes it was chaos. But every attempt to claim it collapses into the same sentence, it cost us a fortune, and a fortune is not a figure anyone can award.
Disruption is a productivity claim. The money is the gap between what the labour should have produced and what it managed in the disrupted conditions, and that gap has to be measured: output in a disrupted period set against output in a comparable undisrupted one, in areas and trades you can isolate, built from allocation sheets, diaries and dayworks. Claims that skip the measurement and assert the total, the whole job just cost more, are precisely the ones that fail scrutiny.
Even with imperfect records, a defensible number can often be built; the judgement is which method the records you actually hold will carry, and that decision has to come first, before a claim gets drafted around a figure that cannot survive its own arithmetic. That is builder's work, done early.
The solution
A number built by method, not assertion.