What is Rework?
Rework is doing work again because it wasn't right the first time — the purest form of internal failure cost and, in most industries, the largest invisible line item in the budget. It hides inside activities ("that task is 90% done… again") rather than appearing as itself, which is why mature projects measure it explicitly.
Its root causes are the usual suspects: unclear requirements, skipped verification, rushed handoffs, drawing revisions outrunning the field. Every dollar of prevention upstream buys several downstream — the entire cost-of-quality argument in one word.
Worked example
A hospital project starts tracking rework as its own code: 7% of all field hours in the first quarter — mostly ductwork clashing with structure because crews worked from superseded drawings. The fix costs almost nothing (a drawing-control hold point and QR-coded current sets at the workface); rework drops to 2%. Nothing about the "schedule" changed, yet the project gains back three weeks it was silently losing.