Is IDS validation the same as model checking?

No. IDS validation checks whether a model contains the information an IDS file requires — classes, attributes, properties, classifications, materials and relationships. Model checking usually also covers geometry: clashes, clearances and spatial rules.

Can IDS detect clashes?

No. IDS has no way to describe geometry, so clashes, clearances and other spatial conditions are checked in a model-checking tool, not with an IDS file.

Do I need a paid model checker to validate against IDS?

No. IDS validation needs only an IDS-capable tool. Bimlyte checks IFC models against IDS 1.0 files in the browser for free, without uploading the model.

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October 31, 2026

IDS validation vs model checking: what each one catches

Quick answer: IDS validation answers “does the model contain the information we asked for?” — the right classes, properties, classifications and materials, with the right values. Model checking usually answers that and “is the geometry right?” — clashes, clearances, spatial rules. A delivery is often checked both ways, and the IDS check is the one that needs no specialist licence.

“Check the model” can mean two quite different things on a BIM project. One is about data: does every door have a fire rating, does every space have a code. The other is about geometry: does the duct clear the beam, is the corridor wide enough. IDS is built for the first, and it is worth knowing where it stops.

What IDS validation checks

An IDS file lists specifications. Each one picks a set of elements — every IfcDoor, every element on a storey, every element with a certain classification — and states what they must carry:

the right IFC class and predefined type;
attributes such as Name or Description;
properties in the right property set, with the right data type;
a classification reference;
a material;
the right relationships — in an assembly, on a storey, in a group.

Values can be fixed, picked from a list, matched against a pattern, kept within a range or limited in length. That covers naming conventions, mandatory parameters, classification systems and most of what an information-requirements document asks for in model data.

The result is per element and per requirement: this wall passes, that door fails because FireRating is missing, these spaces fail because their code does not match the pattern.

What model checking adds

A model checker works on the geometry as well as the data. Typical rule sets cover:

clashes between elements and between discipline models;
clearances — maintenance space around equipment, door swing, headroom;
spatial rules — escape-route lengths, accessibility, room areas;
consistency across models — whether the structural and architectural models agree.

None of this can be written as IDS, because IDS has no way to describe shape or position. It is also where model checkers spend most of their effort, which is part of why they are licensed, installed desktop software.

Which one do you need?

You need to…	IDS validation	Model checker
Confirm mandatory properties and classifications	Yes	Yes
Enforce naming conventions	Yes	Usually
Check the information requirements in a contract	Yes, if they are written as IDS	Yes
Find clashes	No	Yes
Check clearances, escape routes, accessibility	No	Yes
Compare several discipline models	No	Yes
Run without a specialist licence	Yes	Usually not

If the project’s requirements arrive as an IDS file, IDS validation is the direct way to check them: the rules are the client’s own, and any IDS-capable tool reads them the same way. buildingSMART publishes official test cases so that tools agree on what each rule means.

If you are responsible for coordination — clashes, clearances, constructability — you need a model checker, and IDS is at most one input to it.

How the two fit together

On many projects the sequence is:

Each author checks their own model against the IDS before delivery and fixes what is missing.
The BIM manager checks every delivered model against the same IDS on receipt.
Coordination runs in a model checker on the federated model, with clean data to start from.
Findings from either step are tracked as issues — usually BCF.

Running the IDS check early is cheap and catches the boring, common problems — a property set not exported, a classification missing — before they reach coordination.

Where Bimlyte fits

Bimlyte covers the first two steps for free, in the browser: it validates IFC2X3, IFC4 and IFC4X3_ADD2 models against IDS 1.0 files with all six facets and every restriction, explains each failure and shows the values the model actually holds. The result can be coloured on the 3D model and exported to Excel, and the model never leaves your device.

Bimlyte does not run clash detection or geometric rules — that remains the job of a model checker. Clashes found there can still be tracked in Bimlyte as BCF issues.