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Estimating process

Estimate revisions, version control, and audit trail.

Estimates change as information improves, drawings are revised, and prices are updated. A clear version control system ensures everyone knows which version is current and what changed.

Who this guide is for

Estimators managing multiple tender revisions, quantity surveyors tracking estimate updates, and contractors who need to demonstrate how a final price was reached.

Version control basics

Every estimate should have a unique version number, date, and change log. When a revision is issued: record the date, what changed (which items were added, removed, or re-priced), why it changed (drawing revision, new quotation, design change), and who authorised it. Previous versions should be retained, not overwritten.

Miniature example

Estimate version 1.0: £185,400 (based on planning drawings). Version 1.1: £188,200 after updated roof covering quote. Version 2.0: £196,500 after construction issue drawings increased window sizes. The audit trail shows each change with date, reason, and who updated it.

Common mistakes

• Saving over previous versions — no way to see what changed
• No change log — impossible to explain a cost difference between two versions
• Sharing preliminary estimate versions with clients or subcontractors without clearly marking them as drafts