The BIM-manager hands over a clean, federated model. Every discipline is in it, the geometry lines up, it spins nicely on screen. Then the kwaliteitsborger opens it to check one thing against the Bbl, and the property they need is not there. The model looks finished and answers almost nothing. That gap, between a model that looks complete and one you can actually borgen on, is the whole subject of this post.
Under the Wkb, an independent kwaliteitsborger checks during construction whether the building meets the technical rules of the Bbl, and declares whether it complies. Since 1 January 2024 that applies to new builds in gevolgklasse 1, the lowest risk class, where single-family homes and smaller commercial buildings sit. The check is done element by element. So the question is not whether your model is rich. It is whether the right data sits on the right element, named the way a check expects to read it.
Rich geometry, empty answers
An IFC file is objects, not lines. Each wall knows it is a wall: its type, its size, what it is made of, where it sits and what it connects to. buildingSMART keeps the format as an open, international standard, ISO 16739-1, so a model drawn in one tool opens cleanly in another.
The catch is that geometry and data are separate. A model can be exported with every wall present and almost no property behind it. On screen it looks correct. Ask it whether a given wall meets a Bbl requirement and it has nothing to say. The kwaliteitsborger then does what they were trying to avoid: they go back to a folder of drawings and a mailbox, and read the answer off paper.
The identifier is the hook
Every element in an IFC model has its own identifier, stable across the file. buildingSMART describes the schema as carrying three things per element: its identity, including that machine-readable code, its characteristics such as material or thermal properties, and its relationships, such as where it sits and what it is joined to.
That identifier is what turns a vague note into a place. A finding stops being "crack near the second-floor stairwell" and becomes a point on a specific object anyone can walk back to. For a check to run, the property it reads has to be present on that object and named the way the check expects. Missing or mislabelled, and the element is invisible to the borging even though you can see it perfectly well.
Write the requirement down first
Here is the fix that most teams skip: agree the data before the geometry. That is exactly what an IDS is for.
An Information Delivery Specification is a buildingSMART standard, official since 1 June 2024, for stating information requirements in a form a computer can read. It lets you specify which objects, classifications, materials, properties and even values a model must carry, and it allows an IFC model to be checked against those rules automatically. Instead of asking modelers to "add the right data" and hoping, you hand them a machine-readable spec, and both sides validate against it before the model is handed over.
Agree the data, not just the shape
An IDS turns "please include the properties we need" into a file the authoring tool and the checker both understand. The requirement is settled once, up front, rather than argued over at gereedmelding.
What a Wkb-ready model carries
Practically, a model a kwaliteitsborger can work on holds three things. A classification, so elements group and can be found the way the trade thinks (NL/SfB in the Netherlands, Uniclass elsewhere). The specific properties each Bbl check reads, present on the elements they describe, not buried in a separate document. And a stable identifier per element, so a finding, a photo and a certificate stay pinned to the thing they concern.
A Wkb-ready model is not a richer model. It is a model that answers the question you are allowed to ask it.
Where this reaches beyond the Netherlands
None of this is Dutch. IFC and IDS are buildingSMART international standards, the same in Rotterdam as anywhere the standards reach. A model built to an IDS is an openBIM model, and as Europe keeps pushing more building and product data into the open, that portability is worth having. The Wkb is the Dutch expression of a wider European move toward proving building quality with data rather than paper. A clean, classified, checkable model is what that move runs on, in any language.
Where we come in
BimDossier reads the IFC you are sent, loads federated models from every discipline into one viewer, and lets you pin a finding to an element by its own identifier, with a photo and an owner. The compliance engine runs its rule packs against that same IFC data. A model that is IDS-conform and Wkb-ready makes the borging directly executable, instead of a manual clean-up before you can even start. The snags, the certificates, the Wkb dossier, all of it still sits on your model.