BIM quantities to BC3: keep your estimate traceable

Moving BIM quantities to BC3 requires being able to explain which objects and measurement rules produce each estimated quantity. This guide addresses that workflow; it does not announce a new format version. ITeC’s technical training covers linking objects to estimate items and managing successive imports: separate tasks worth preparing before exchanging files with another team or the ERP.

Link the object identifier, source model and revision, location, destination item, unit and measurement rule. An estimate item identifier does not replace an object identifier: several objects can feed one item, and one object may contribute to several work items. Keep the relationship in the measurement application or a controlled supporting register. Do not assume the receiving application will retain all those references within the BC3 file.

Record which lines originate in the model and which relate to work measured outside it. Temporary protection or finishing work may need an independent measurement. If that line is mixed into the imported total without its origin, a later import may duplicate or remove it. Give each contribution an owner and an update rule, and avoid using a manual figure to hide a model discrepancy.

A set of objects contributes 120 m² to an item, while an area not yet modelled adds 8 m² measured manually. The estimate contains 128 m² with two identified sources. If the model contribution becomes 125 m² and the manual area remains outside its scope, the new total would be 133 m². If that area is now included in the updated model, keeping the 8 m² would double-count it. The decision depends on scope, not merely subtracting totals.

Keep the original and open the BC3 file in the destination application. Review a sample of items with multiple lines, different units and manual contributions. Check hierarchy, quantities and descriptions, and trace a quantity back to its source evidence. If BIM references do not travel or are not interpreted, agree how to deliver the supporting register and link it to the estimate version. BC3 and IFC serve different purposes; exchanging one does not prove that every relationship in the other has been transferred.

Before integrating, agree how the item maps to the project and its management codes, which revision is approved and who resolves an unmapped line. Run a second trial import and check that it neither duplicates contributions nor overwrites unrelated data. CADT can review a sample file and its measurement workflow to define a traceable BC3 exchange and an ERP integration suited to your process.