Estimate revisions

Estimates change because the project changes: layout revisions, foundation strategy, supplier quotes, labour assumptions, and commercial policy. The failure mode is not change. The failure mode is losing the previous defensible number.

Drafts and revisions

The estimating engine distinguishes draft state from a base revision. Lines have row versions. Mutations such as quantity changes, rate changes, added or removed lines, escalation, quote import, and scenario creation are auditable events rather than silent cell edits.

That design supports undo/redo and “what changed?” conversations that spreadsheets usually cannot answer.

Scenarios

Scenarios let a team compare commercial pictures — for example a higher labour-rate case — without forking the entire file. Scenario lineage should remain visible so a reviewer knows which assumptions differ.

Why revisions matter downstream

Procurement packages and Project Controls forecasts should inherit an approved estimate revision. If the field is working from Rev 3 while commercial is still editing an unnamed draft, variance reports become arguments.

Practical discipline

• Name the revision that was issued to procurement
• Do not paste a new total into a dashboard without recording the revision
• When a layout revision lands, re-compile from quantities rather than hand-editing a handful of lines that “probably changed”

See also Why estimate traceability matters.