Understanding The Different Types of Construction Cost Estimates Throughout The RIBA Stages
As a construction project progresses through the RIBA (Royal Institute of British Architects) stages, there are different types of cost estimates that are used to determine the total cost of the project. It is essential for architects, quantity surveyors, and other construction professionals to understand these different types of cost estimates to ensure the project stays within budget. In this article, we will discuss the various types of cost estimates used throughout the RIBA stages.
Stage 0 – Strategic Definition: Order of Magnitude Estimate
During this stage, the order of magnitude estimate is used to provide a rough estimate of the project’s cost. This type of estimate is used to inform decisions related to the project’s viability and feasibility. It is based on a limited amount of information, such as the size and type of building, and is typically expressed as a range of costs per square meter.
Stage 1 – Preparation and Brief: Elemental Cost Plan
In this stage, the elemental cost plan is used to provide a more detailed estimate of the project’s cost. This type of estimate breaks down the project into different elements, such as the substructure, superstructure, and services. The cost of each element is estimated separately, and then the total cost is calculated. The elemental cost plan is used to inform decisions related to the project’s scope and budget.
Stage 2 – Concept Design: Concept Cost Plan
During this stage, the concept cost plan is used to provide a more detailed estimate of the project’s cost. This estimate is based on a more developed design and takes into account the materials, construction methods, and other details that have been determined during the concept design stage. The concept cost plan is used to inform decisions related to the project’s design and budget.
Stage 3 – Developed Design: Detailed Cost Plan
In this stage, the detailed cost plan is used to provide a more accurate estimate of the project’s cost. This type of estimate takes into account all the details of the project’s design and provides a breakdown of the cost of each item, such as materials, labor, and equipment. The detailed cost plan is used to inform decisions related to the project’s design, budget, and procurement.
Stage 4 – Technical Design: Tender Documentation
During this stage, the tender documentation is used to provide a detailed breakdown of the project’s cost. This document is used to obtain bids from contractors and subcontractors and is based on the detailed cost plan. The tender documentation includes a bill of quantities, which provides a detailed breakdown of the materials, labor, and equipment required for the project. It is used to inform decisions related to the project’s procurement and contractor selection.
Stage 5 – Construction: Cost Control
In this stage, cost control is used to monitor the project’s actual cost and compare it to the estimated cost. This is done through regular cost reports and progress meetings with the contractor. Any changes or deviations from the original plan are identified and addressed to ensure the project stays within budget.
In conclusion, understanding the different types of cost estimates used throughout the RIBA stages is essential for ensuring a construction project stays within budget. Architects, quantity surveyors, and other construction professionals must have a clear understanding of each type of estimate and how they are used to inform decisions related to the project’s scope, design, procurement, and budget.
