By default, “Export room geometry” is marked in the settings of the Navisworks exporter plugin in Revit. If you unmark this box, the room geometry will no longer be included in the exported model.
Before Exporting, in the export window, click Navisworks Settings, and you’ll see this checkbox.
Alternatively, if you take your exported NWC that includes the room elements as geometry, select those elements and Hide them in the current viewpoint, when you run a clash test, those elements will be ignored.
Please let me know if this resolves the issue.
John Lipp Support Specialist Product Support Autodesk, Inc.