QS Guide · Chapter 03

Cost Planning — AIQS Stages A–F

The six-stage AIQS cost planning framework, from feasibility (Stage A) through final cost statement (Stage F). Confidence intervals, deliverables, and decision gates at each stage.

QS Guide Chapter 03 of 5

00Overview 01Introduction 02Methods of Measurement 03Cost Planning 04Contract Administration 05Final Account

Cost Planning

AIQS Cost Planning Stages A–F

AIQS publishes a structured cost planning framework with six stages, each tightening the estimate as design progresses. The stage names map directly to common project gateways and can be referenced in client briefs or appointment scopes.

Stage A — Initial Cost Plan

Prepared at the project initiation phase from a brief, not drawings. Uses elemental rates per m² of GFA (or per kilometre of road, per MW of installed capacity, etc.) drawn from comparable past projects. Confidence is wide — typically ±25%. Purpose is to test feasibility and establish a target capital cost for business case development.

Stage B — Strategic Cost Plan

Prepared when concept design is available. Refines elemental rates for project specifics — site conditions, height, finish quality, services intensity. Confidence narrows to ±15%. Purpose is options selection and scope freezing.

Stage C — Detailed Cost Plan

Prepared at the end of schematic / preliminary design. Uses measured quantities for major elements (substructure, structure, envelope) and elemental rates for remaining work. Confidence ±10%. Purpose is to confirm budget against the developed design and identify any value engineering opportunities.

Stage D — Pre-Tender Estimate

Prepared from full developed design and specification immediately before tendering. Approaching the level of detail of a full BOQ. Confidence ±5%. Purpose is to set the tender benchmark — anything materially above the Stage D estimate is investigated as a tender market issue or scope creep.

Stage E — Post-Tender Estimate & Reconciliation

Prepared after tenders are received. Reconciles the recommended tender against the Stage D estimate, explains material variances, and converts the tender into a contract sum baseline.

Stage F — Final Cost Statement

Prepared at project completion. Reconciles final paid value against original contract sum, documents all variations and EOT cost claims, and closes the project commercially. Same exercise as the final account (covered in Chapter 05).

Best Practice Costing Manual

AIQS publishes the Best Practice Costing Manual (BPCM) as the practitioner reference for cost planning, elemental cost analysis, and cost reporting. Cenex's cost plans follow the BPCM structure so they are immediately recognisable and auditable by clients, lenders, and other QS practitioners.

Common Questions

Frequently Asked Questions

Indicative confidence ranges: Stage A initial cost plan ±25%, Stage B strategic ±15%, Stage C detailed ±10%, Stage D pre-tender ±5%. The actual range depends on project complexity, design completeness, market conditions, and the depth of historical data available. Cenex always documents the assumptions, exclusions, and confidence range on the front of every cost plan.

Elemental Cost Analysis breaks a building or asset down into its functional elements (substructure, structure, envelope, services, etc.) and reports the cost and area of each. ECA from completed projects is the data feed for Stage A and Stage B cost plans on future projects. AIQS publishes the standard ECA structure that Cenex uses for cost reporting.

A live cost plan is the engine of effective value engineering. Without a current cost plan, value engineering becomes uninformed scope reduction. With a properly maintained cost plan, the team can quantify the cost impact of design alternatives in real time and select the best total-value option — not just the cheapest.

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