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IFC classes and clash detection

Give modelled objects their IFC classes, and find where models run into each other.

Stori3D's walls, floors, roofs, stairs, columns, doors, windows and furniture go to IFC as what they are. Here's how to class everything else, and how to check models against each other before they go out.

Give an object its IFC class

Select a shape, a group or component, or part of a model you've brought in, and pick its IFC class in Properties, as SketchUp's Classifier does: Beam, Column, Covering, Curtain wall, Footing, Member, Plate, Railing, Slab, Wall, Sanitary terminal, Light fixture and more. IFC type says what kind it is, in words, such as Glass balustrade.

When you export IFC, it goes out as that class. A group or component given a class goes out as one element, with all its parts. Anything left unclassed goes out as a building element proxy.

Find clashes

Choose More tools → Clash detection… (or search for it with Shift+S).

1. Check one set Against another. A set is the building as modelled, the furniture, a model you've brought in (such as the structural engineer's IFC), or everything on a tag. A set can be checked against itself.
2. Set the Tolerance: overlaps smaller than this count as touching, not clashing. 10 mm is a good start.
3. Press Find clashes.

The clashes are listed worst first, with how far one runs into the other, or inside when one sits wholly within the other. Pick one to select both objects, frame them, and box the overlap in red; Previous and Next step through the list.

Faces that only touch, such as a sofa against a wall, aren't clashes. Nor are the building's own joins, where walls meet walls and floors, or doors and windows in their walls.

To check a consultant's model, import its IFC (see Importing), then check it against the building.

Track clashes from one run to the next

Each clash keeps a status, as in Navisworks. It's New the first time it's found and Active when it's found again. Mark one Reviewed once you've looked at it, or Approved to accept it as it is; those stay as you set them. A clash that isn't found any more is Resolved, and Resolved since an earlier run lists them. Pick a clash to set its Status and add a Note. They're kept with the project.

Show groups the list: By object (one duct through five walls is one problem), By level or By status. Turn off Show approved clashes to see only what's left to sort out.

Export as BCF saves the clashes as BCF issues, one per clash, each with the two elements, a view framing them, a picture, its status as a label and your note. Approved and resolved clashes go as closed issues. The consultant opens the file in their own tool (Revit, Archicad, Solibri, Navisworks or BIMcollab), which finds the elements by their IFC ids: those of your IFC export, or the consultant's own for parts of their model.

Still stuck? Contact us, or ask in the app: Help → Contact support.