Definition from IAI: Definition for any 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, floor and ceiling coverings, 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 either a space boundary, using the inverse relationship ProvidesBoundaries pointing to IfcRelSpaceBoundary, or to a building element, using the inverse relationship Covers pointing to IfcRelCoversBldgElements.
IFC2x PLATFORM CHANGE: With the upward compatible platform extension at IfcRelCoversBldgElements the IfcCovering can now also cover an IfcElement (and its subtypes in addition toIfcBuildingElement).
The following guideline shall apply:
- if the space has defined space boundaries, then the covering, which relates to that space, should be assigned to the space boundaries
- if the space has no space boundaries defined, or the covering does not relate to a space, then the covering should be assigned to the building element
The quantities relating to the covering 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:
| Name | Description | Value Type |
| CoveredArea | Total area of the covering in the elevation view. The exact definition and calculation rules depend on the method of measurement used. | IfcAreaQuantity |
HISTORY New entity in IFC Release 1.0.
Geometry Use Definitions
The geometric representation of IfcCovering is given by the IfcProductDefinitionShape, allowing multiple geometric representation. Included are:
Local Placement
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 PlacementRelTo relationship of IfcLocalPlacement shall point (if given) to the same IfcSpatialStructureElement , which is used in the ContainedInStructure inverse attribute, or to a spatial structure element at a higher level, referenced by that.
- If the IfcCovering, however, is assigned to an IfcBuildingElement, and this element defines its own local placement, than the PlacementRelTo relationship of IfcLocalPlacement shall point (if given) to the local placement of the IfcBuildingElement.
- If the relative placement is not used, the absolute placement is defined within the world coordinate system.
Geometric Representations
The geometric representation of the IfcCovering depends on two criteria:
- Does it define an area or a volume?
- Is the base surface (either the IfcRelSpaceBoundary or the surface of the IfcBuildingElement it relates to) a planar surface or a cylindrical surface?
GeometricSet Representation
The standard geometric representation of IfcCovering supports area definitions as 3D surfaces. The standard geometric representation of IfcCovering is defined using the following representation types:
- for planar base surfaces - bounded surface representation
- for cylindrical base surfaces - swept surface representation
EXAMPLE for standard geometric representation.
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The area of IfcCovering is given by an IfcPolyLoop for planar base surfaces (here given by the IfcRelSpaceBoundary).
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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).
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SweptSolid Representation
The advanced geometric representation of IfcCovering supports volume definitions as 3D solids. The advanced geometric representation of IfcCovering is defined using the following representation types:
- for planar base surfaces - swept area representation
- for cylindrical base surfaces - swept area representation
EXAMPLE for advanced geometric representation.
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The volume of IfcCovering is given by an IfcExtrudedAreaSolid for planar base surfaces (here given by the IfcRelSpaceBoundary).
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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).
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