Building Information Modelling (BIM) has become an increasingly important digital workflow within the construction industry. For quantity surveyors, BIM can provide a structured environment for reviewing model information, measuring quantities and connecting project information with cost planning.
What Is 5D BIM?
5D BIM generally refers to the integration of cost information with a three-dimensional building information model. While 3D BIM focuses primarily on the physical representation and information within a project model, the addition of cost information provides another dimension for quantity and commercial analysis.
In quantity surveying practice, this can involve linking model elements and measured quantities with rates, cost information or other commercial data. The exact workflow depends on the software, model structure and project requirements.
How 5D BIM Supports Quantity Surveying
5D BIM does not replace professional quantity surveying judgement. Instead, it can complement established measurement and cost management processes by providing another way of accessing and reviewing project information.
Measuring Quantities from Model Information
BIM models can contain information about building elements, dimensions and quantities. Where the model is suitably structured, quantity surveyors can use model information to support digital quantity measurement and review.
Connecting Quantities with Cost Information
Model-based quantities can be combined with appropriate rates and cost information to support cost planning and budget analysis. This can provide a structured basis for reviewing how changes in design may affect measured quantities and cost.
Reviewing Model Information Across Disciplines
BIM coordination can bring architectural, structural and building services information into a common digital environment. Quantity surveyors can use coordinated model information to support measurement and identify areas that may require clarification.
Understanding the Cost Impact of Design Changes
As the design develops, model information may change. Reviewing quantities and associated cost information can help project stakeholders understand the commercial implications of design development and scope changes.
Supporting Structured Cost Analysis
Model-based information can support commercial review by providing a digital reference for quantities, building elements and areas of the project. Professional assessment remains necessary to interpret the information in accordance with the project scope and contractual requirements.
The Importance of Model Quality
The usefulness of 5D BIM depends heavily on the quality and completeness of the underlying model. Incorrect, incomplete or poorly structured model information can affect the reliability of quantities extracted from the model.
Quantity surveyors should therefore review model information, assumptions, measurement rules and project requirements before relying on model-derived quantities for commercial purposes.
5D BIM and Traditional Quantity Surveying
Digital BIM workflows and conventional quantity surveying methods can work together. Depending on the project, quantities may be measured from models, drawings, schedules or a combination of available information.
Professional judgement remains important when determining the appropriate measurement approach, particularly where model information does not fully represent the construction scope.
5D BIM in the Construction Stage
During construction, BIM-based quantity and cost information can support review of project changes, quantities, procurement information and commercial records where the model is maintained and updated appropriately.
The level of BIM use should be aligned with the project's information requirements, contractual arrangements and available digital resources.
Key Considerations Before Adopting 5D BIM
Model Structure
The model should contain sufficiently structured and relevant information for the intended measurement and cost workflow.
Measurement Rules
Appropriate measurement principles and project-specific requirements should still be applied.
Cost Data
Rates and cost information need to be appropriate, current and relevant to the project scope.
Professional Review
Model-derived information should be reviewed and interpreted by appropriately qualified professionals.
5D BIM can complement quantity surveying by connecting model information, quantity measurement and cost data within a structured digital workflow, while professional quantity surveying judgement remains essential.