BIM vs. Bills of Quantities. Will 3D Model Takeoff Software Eliminate The Need for Quantity Surveyors and Estimators in Construction Projects?

Virtual Bedroom – An Architectural 3D CAD Model of Bedroom Interior

BIM stands for Building Information Modelling. There are many perspectives in which people view BIM. It is essential to know that BIM evolved as an architectural design process based on digital 3D Modelling, but instead of the Architect being the only one involved in the design process, it is now inclusive of other parties involved in the project i.e. Structural, Mechanical, Electrical, Civil, Waste/Water Engineers, Environmental Planners as well as Building Contractors and the Owner.  While others see it as a 3D software for modelling or simulating the real-life physical design of a building, others see it as a communication tool for team collaboration, i.e. everyone involved in the project can view or provide input on the real-time model via a centralized system or cloud-based service. Some see it as a reliable dynamic database for getting up to date specifications and changes to the building design. Still, others think it’s a great tool for risk management and trouble shooting, allowing clashes, discrepancies and issues to be identified in the model before construction working drawings are sent to the contractor. For an Estimator or Quantity Surveyor, BIM might be seen as a tool for automating the production of error-free quantities from live models and eliminating manual takeoff from paper and digital blueprints. For the client (building owner), BIM will be a platform that allows him or her to monitor the design and actually see the progressive 3D visual representation of the building at any stage of the project. This gives the owner control over the design. Since every party knows what is taking place at any point, BIM provides transparency to the project as a whole. Some have compared BIM to a 3D simulation video game where the user can actually enter a virtual building and open doors to the bedroom, kitchen, living room, bath etc, enabling the user to see how the rooms look like.

BIM and the Future of Quantity Surveying

Although automating the measurement of building quantities is something that will speed up the production of cost estimates and reduce the workload for a Quantity Surveyor, it is something that has created a cause for concern for an Estimator’s job security. With the development of auto-takeoff software that can link to a BIM platform, for example CostX, and BIM solutions like Revit that have inbuilt capabilities for producing quantities automatically, people in the construction industry i.e. Architects, Civil Engineers, Project Managers, Property Developers including Quantity Surveyors themselves, have been talking about the advent of 3D auto-measuring software that will make the role of Quantity Surveyors redundant.

Will BIM eliminate the need for Estimators and Quantity Surveyors in a construction project? Although some people think so, BIM or any 3D Model-based estimating software will not kill the Quantity Surveying profession. In the early days of the profession, a Quantity Surveyor’s main role was solely taking off measurements from a plan, but the modern Quantity Surveyor has far more roles than taking off quantities. The modern Quantity Surveyor has a broader portfolio of responsibilities which include estimating,  cost planning, documentation, tender administration, contract administration, progress valuations, financial management , cost control, dispute resolution, facility management, risk management, asset management, contract law consultation, construction firm management consultation and project management services.

BIM-based auto-measuring software will allow anybody to generate quantities, a task that could only be done by quantity surveyors using on-screen takeoff programs or paper dimension sheets. However, here comes the problem – although any user can generate quantities with BIM auto-takeoff, it will take the skill of a professional Quantity Surveyor to analyze and interpret the data.

Accountants as Estimating Technicians

Some people have spoken of Accountants taking over the role of the Quantity Surveyor but what these people forget is that an Accountant does not have the Quantity Surveying technical knowledge and skills that are acquired in college training as well as on site. This lack of knowledge will not put the Accountant in a better position to analyze and interpret auto-measured quantities.

People tend to forget that a full-time Quantity Surveying course at the university or polytechnic is a balanced and well-rounded course where students take compulsory subjects in Measurement of Construction Work, Building Drawing, Construction Technology, Building Materials, Soil Mechanics, Engineering Mathematics, Surveying, Project Management, Construction Economics, Theory of Structures and Communication. All these subjects help the QS to understand the construction process and interpret the items in a Bill of Quantities as well as on site. The Accountant does not have this kind of knowledge and training which is critical in the construction industry.

BIM takeoff software will not kill the quantity surveying profession but it will give Estimators and Quantity Surveyors a new role as BIM cost estimating managers. It will also allow estimators to focus on major roles that have been stated in the earlier paragraphs. With BIM, a Quantity Surveyor will not need to measure quantities manually, a process that takes too much of an estimator’s time.

BIM versus Bills of Quantities. What is the Difference?

The information contained on a BIM platform is always current and more detailed than what you would find on a 3D AutoCAD file. At the same time, Bills of Quantities contain more information than an AutoCAD file. For example, Bills of Quantities contain detailed item descriptions, preambles to trades and specifications. Now imagine that detailed information on a BIM system, i.e. linked to 3D CAD objects, for example walls, floor finishes, plumbing and drainage etc. Updating and making changes to the model will auto-update the quantities and everything connected to the object in real time.

The difference between BIM Quantities and Bills of Quantities lies in their method of production and preparation.

BIM System

• A quantity surveyor is not needed to take off measurements
• Quantification happens automatically as the model takes shape
• Any changes to the model are translated to all connected aspects of the building, no remeasurements needed.
• BIM quantities can be extracted for costing by the estimator i.e. the user can send the quantities to an estimator for costing.
• BIM quantities are generated instantly allowing quick cost estimates

Bills of Quantities

• A quantity surveyor is needed to take off measurements
• Quantities are built through manual on-screen input on a dimension sheet
• QS has to re-measure work when changes are issued by the architect and engineers
• After measuring, the QS has to price the Bill
• It takes a long time to produce BOQ quantities i.e. several days or weeks

BIM Explained on YouTube Video: