Definition from ISO 6707-1:1989: term used: Finishing - final coverings and treatments of surfaces and their intersections.
Definition from buildingSMART: A covering is an element which covers some part of another element and is fully dependent on that other element. The IfcCovering defines the occurrence of a covering type, that (if given) is expressed by the IfcCoveringType.
EXAMPLEs include wall claddings, floorings and suspended ceilings as well as finish trim and base molding.
IFC2x PLATFORM CHANGE: The attribute PredefinedType is now optional and should only be inserted when there is no type information, given by IfcCoveringType, is assigned to the IfcCovering occurrence by IfcRelDefinesByType.
Coverings can be assigned to
IFC2x PLATFORM CHANGE With the upward compatible platform extension at IfcRelCoversBldgElements the IfcCovering can now also cover an IfcElement (and its subtypes in addition to IfcBuildingElement). Additional enumerators have been added to IfcCoveringTypeEnum to identify coverings applicable to elements other than building elements.
The following guideline shall apply:
HISTORY New entity in IFC Release 1.0.
Type Use Definition
The IfcCovering defines the occurrence of any covering, common information about covering types (or styles) is handled by IfcCoveringType. The IfcCoveringType (if present) may establish the common type name, usage (or predefined) type, common set of properties, common material layer set, and common shape representations (using IfcRepresentationMap). The IfcCoveringType is attached using the IfcRelDefinedByType.RelatingType objectified relationship and is accessible by the inverse IsDefinedBy attribute.
As an additional use agreement for standard coverings (i.e. slabs with constant thickness along the extrusion direction), the IfcCoveringType should have a unique IfcMaterialLayerSet, that is referenced by the IfcMaterialLayerSetUsage assigned to all occurrences of this covering type.
Assignment of IfcMaterialLayerSetUsage and IfcMaterialLayerSet to the covering type and the covering occurrence.
If an IfcCoveringType is assigned to the IfcCovering, the attribute PredefinedType shall not be assigned, or shall be identical to IfcCoveringType.PredefinedType.
Property Set Use Definition:
The property sets relating to the IfcCovering are defined by the IfcPropertySet and attached by the IfcRelDefinesByProperties relationship. It is accessible by the inverse IsDefinedBy relationship. The following property set definitions specific to the IfcCovering are part of this IFC release:
Quantity Use Definition:
The quantities relating to the IfcCovering are defined by the IfcElementQuantity and attached by the IfcRelDefinesByProperties. The following quantities are foreseen, but will be subjected to the local standard of measurement:
|GrossArea||Total area of the covering in the elevation view. The exact definition and calculation rules depend on the method of measurement used.||IfcQuantityArea|
|NetArea||Total area of the covering in the elevation view taking into account possible openings. The exact definition and calculation rules depend on the method of measurement used.||IfcQuantityArea|
Geometry Use Definitions
The geometric representation of IfcCovering is given by the IfcProductDefinitionShape, allowing multiple geometric representation. Included are:
The local placement for IfcCovering is defined in its supertype IfcProduct. It is defined by the IfcLocalPlacement, which defines the local coordinate system that is referenced by all geometric representations.
The geometric representation of the IfcCovering depends on two criteria:
The 'GeometricSet' geometric representation of IfcCovering supports area definitions as 3D surfaces.
The following additional constraints apply to the 'GeometricSet' representation of IfcCovering:
EXAMPLE for standard geometric representation.
The area of IfcCovering is given by an IfcPolyLoop for planar base surfaces (here given by the IfcRelSpaceBoundary).
The area of the IfcCovering is given by an IfcSurfaceOfLinearExtrusion for cylindrical base surfaces (here given by the IfcRelSpaceBoundary - e.g. caused by a round wall).
The 'SweptSolid' geometric representation of IfcCovering supports volume definitions as 3D solids.
The following additional constraints apply to the 'SweptSolid' representation of IfcCovering:
EXAMPLE for advanced geometric representation.
The volume of IfcCovering is given by an IfcExtrudedAreaSolid for planar base surfaces (here given by the IfcRelSpaceBoundary).
The volume of the IfcCovering is given by an IfcExtrudedAreaSolid for cylindrical base surfaces (here given by the IfcRelSpaceBoundary - e.g. caused by a round wall).
|PredefinedType||:||Predefined types to define the particular type of the covering. There may be property set definitions available for each predefined type.|
Reference to the objectified relationship that handles the relationship of the covering to the covered space.
|WR61||:||Either the PredefinedType attribute is unset (e.g. because an IfcCoveringType is associated), or the inherited attribute ObjectType shall be given, if the PredefinedType is set to USERDEFINED.|