An Order of Cost Estimate is an early-stage cost prediction prepared during the feasibility and strategic briefing stages of a construction project. It provides clients with an indication of likely costs before detailed design work begins.
Definition
According to the RICS Professional Statement on Cost Prediction (2020), an order of cost estimate is defined as:
“An estimate based on benchmark data for a similar type of project based on a defined brief.”
Methods of Preparation
Order of cost estimates can be prepared using several methods:
- Floor area method – Cost per square metre of gross internal floor area (GIFA)
- Functional unit method – Cost per bed space, per pupil place, per car parking space, etc.
- Elemental method – Using elemental cost data from BCIS or similar sources
When Its Used
Order of cost estimates are typically prepared at:
- RIBA Stage 0 (Strategic Definition)
- RIBA Stage 1 (Preparation and Brief)
- Early RIBA Stage 2 (Concept Design)
Accuracy
Due to limited design information, order of cost estimates typically have an accuracy range of ±15-20%. They include appropriate contingencies to reflect this uncertainty.
Related Terms
See also: Rough Order of Magnitude, Cost Estimation, Preliminary Estimate
