Quantity Take-off

Having accurate quantities on-hand with every design iteration from the early stages of the project is a major advantage for the owner to estimate the project budget.

Integrating the BIM Models to Quantity Take-off process can be categorized into 2 stages;

Conceptual Quantity Take-off

Quantity Take-off at the conceptual design level is a basic calculation of all the components that are incorporated into the BIM Model in count, length, area, volume etc. Most of the BIM Modeling software tools have in-built quantity features to help accurately quantity all the 3D elements in the model

However, to successfully use the BIM Models for QTO, the models need to be developed following a specific Modeling Standards. Having pre-set templates for all the quantities at this stage built into the model file will keep the process efficient.

Detail Quantity Take-off

As the design progresses to design development and tender stages, the level of information required for cost estimation also increases. The quantity take-off at this stage requires to be much more in detail and documented in a certain format.

Level of Detail Matrix

Quantity take-off models apart from being organized following a certain standard, they are also required to carry information specific to quantity take-off to enable seamless information exchange. The element level information requirements should be standardized in the LOD Matrix before initiating the modeling process.

Quantity Take-off Software

A typical BIM Modeling software will not be able to accommodate the detail quantity take-off activities involved in a project. Apart from being able to import the 3D Models from the modeling tools, Quantity Take-off software requires to have certain features to help accurately quantify the 3D Model and organize the information in a required format for cost estimation.

Information Exchange Standards

Accurate exchange of information from Models to Bill of quantities defines the accuracy levels of the estimated cost. The information exchange standards should be developed based on the quantity calculation rules that are specific to the local practice. Having a bi-directional integration between the BIM Model and the Quantity Take-off tool will help keep the Quantities accurate and updated along with the BIM Models changes and vice versa.

Bill of Quantity Templates

ndustry standard practice of estimating a project involves documenting the Quantities in a certain format with information specific to costing. Traditionally, BOQ templates used are manually updated and information is added as and when missing. However, it is very important to standardize the BOQ templates early in the process to help the design team to work towards meeting the end goal.