Roofs are aggregates and shall have at least one contained element and no own geometry [withdrawn 2012-02-06]
Based on IFC2x3
Initiator ISG Meeting-Prague
Effects Extended Coordination View
Date 2008 02 26
The IfcRoof should only be exported as an aggregate without having an own geometric representation. As a minimum, one contained element shall be included having the geometric representation. This would normally be an IfcSlab with PredefinedType=ROOF.
Update: Withdrawn 2012-02-06
This implementer agreement has been withdrawn with immediate effect. The IFC2x3 Coordination View 2.0 compliant applications shall support the import of IfcRoof with own geometric representation and without components.
This is to unify the requirements (e.g. to equally apply to also IfcCurtainWall, IfcStair, IfcRamp. etc.