Technical | 4 min read

Quantity Surveying BIM Attribute Requirement (QSBAR)

Learn more about the comprehensive guideline on how to align the BIM model with the standard method of measurement (SMM) that conforms to Quantity Surveyor's requirement. Continue reading to find out how the Quantity Surveyor can handle a BIM model.

BIM Sharing Session - Glodon Singapore

Quantity Surveying BIM Attribute Requirements (QSBAR) was first introduced last 13 July 2018 during the BIM Sharing Seminar organised by Singapore Institute of Surveyors and Valuers (SISV) in collaboration with Glodon Singapore.

QSBAR is a set of documents published by SISV, which explains the requirements of BIM in Cost Management. QSBAR gives a detailed Cost Breakdown Structure of the elemental attributes and geometry required within a BIM model which is aligned to the standard method of measurement (SMM). It acts as a guide for the Design Consultants to model the BIM to the Quantity Surveyor’s requirements. It also highlight the necessary elements for the QS/Estimator to be extracted from the BIM model.

The QSBAR basically combines the BIM Model with QS/Estimator requirements. The elements within the BIM Model has been enhanced with more information. This information is important for a QS/Estimator to quantify and generate the necessary reports. In fact, most of the fundamental elements in a BIM model have been listed in the QSBAR and have been described according to the Quantity Surveyor Standards Method of Measurement. For example, floors elements in the BIM Model should include the name and description according to the QSBAR.

QSBAR Elemental Descriptions & UoM

QSBAR Elemental Descriptions & UoM

Another critical information added is the Unit of Measure (UoM). BIM Model might only contain some basic dimensions, but they may not have the correct UoM or not calculated to the required measurements as required by a QS/Estimator. Thus, the QSBAR specifies how each element should be correctly measured from a BIM model, or how the measurements (including their UoM) should be contained within a BIM Model. 

When dealing with BIM models, the information contained within the model are sometimes limited to a certain level. This level of information is subjected on how the models are modelled to certain level of geometrical details. The level of detail combined with the level of information forms the level of development (LOD). In this case, the LOD 200, 300 and 350 have been currently specified in the QSBAR, including the dimensions required in the BIM model.

QSBAR Elemental Dimensions for required LODQSBAR Elemental Dimensions for required LOD

These specifications and standards are particularly important when using Cubicost, as it is built based on these required standards. Once this information has been clearly defined and specified in the BIM model, the measurement and quantities required by the QS/Estimator can be extracted and categorized according to the required names and descriptions of the elements. As a result, the efficiency in measurement is greatly enhanced.

However, in the actual situation or during the learning stage of the industry, BIM models might not be modelled with the required specifications. But this does not mean that the BIM model cannot be used in this case. The BIM model is still useful and the information can still be extracted but it will require both the modellers and the QS/Estimators to communicate to achieve each objectives. This has been done as more and more firms are seen collaborating and working on the model learning from each other and learning from the model. Due to this existing state, QS/Estimator can transit from 2D plan measurement to forming their own 3D Cost/Measurement Model from the 2D drawings. Like from the earlier period, having a model during the CAD days is a dream. But it has been realized today. Now, to reach the ideal BIM model, will it be merely a dream? 

Quantities generated from BIM Model - Cubicost TAS Calculation with SMM according to QSBARQuantities generated from BIM Model - Cubicost TAS Calculation with SMM according to QSBAR

The specifications according to the QSBAR only acts as a guideline. It is recommended that each firm should participate and make it relevant and suitable according to internal organisation’s practice and to the project’s BIM Execution Plan (BEP).

The efficiency and effectiveness of this is achievable, however, it can only be unlocked to its full potential if the QS/Estimator learns how to interpret the BIM model, same as to how they interpret from a PDF/CAD Drawing. Handling a BIM model requires a new skill sets and the ability to see the information within a BIM model. It will not be the same process like the measurements on PDF/CAD drawings. The information in a BIM model is far more different to what it seems if compared to the 2D drawings. Hence, in this situation the QS/Estimator will be better in adopting BIM once they start to deal more with BIM models, but at the present moment, a more relevant Cost/Measurement Model, created by them with the availability of 2D Drawings and 3D Model provided is the recommended best practices. As the trend of BIM continuous to develop, the QS/Estimator will evolve into a BIM QS/Estimator who will then be able to handle BIM models and work more closely together with other parties within the BIM environment of a BIM project.

Click here to download the QSBAR

Where to find it: At the Left Menu, Click BIM > QSBAR 

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