5D BIM Quantities Explained
Every take-off tool sits on one of two paths:
- The read-only path — IFC, DWF, DWFx — measures a frozen export of the model. It works beautifully… until the design changes. Then you re-export, re-import, and re-measure. Every revision. Every time.
- The native path reads the live Revit model. Like today’s AI-powered humanoids, it senses the change and adapts — quantities re-measure the instant the model moves.
QSKing believes in the native path for 5D BIM Cost Management because native BIM models have instant geometry update capability, e.g. Revit, Tekla, ArchiCAD. In this edition, we shall start with the most commonly used Revit (.rvt) and move on to the others as we go. In contrast, IFC, DWF, and DWFx BIM models are read-only — they are not capable of instant updates.
NATSPEC National BIM Guide (2022) 7.1(2) Cost management (5D modelling) also asks for “…automatically updated as changes are made, negating the need for manual remeasurement.”
Cost = Quantities x Unit rates. Quantities play a vital role in Cost Management, and a standard method of measurement like ANZSMM 2022 is the best guide to producing a Bill of Quantities that forms part of the building contract. For this reason, QSKing has mapped these measurement rules into Revit (.rvt) for automatic extraction of quantities.
With QSKing, all you have to do is use the Run QTO command and link the line items to the Workbook. The linked quantities will automatically update as the design progresses.
You do not need to know all the Revit design tools in order to do 5D BIM Cost Management. A basic understanding of the Revit Quick Start Guide will suffice. You must log in to view all the tutorials and video clips — they are all free. This comes with a 30-day free trial as well.