The building storey has an elevation and typically represents a (nearly) horizontal aggregation of spaces that are vertically bound.

A storey is (if specified) associated to a building. A storey may span over several connected storeys. Therefore storey complex provides for a collection of storeys included in a building. A storey can also be decomposed in (horizontical) parts, where each part defines a partial storey. This is defined by the composition type attribute of the supertype IfcSpatialStructureElements which is interpreted as follow:

EXAMPLE  In split level houses, a storey is split into two or more partial storeys, each with a different elevation. It can be handled by defining a storey, which includes two or more partial storeys with the individual elevations.

The IfcBuildingStorey is used to build the spatial structure of a building (that serves as the primary project breakdown and is required to be hierarchical). The spatial structure elements are linked together by using the objectified relationship IfcRelAggregates.

Figure 113 shows the IfcBuildingStorey as part of the s patial structure. It also serves as the spatial container for building and other elements.

NOTE  Detailed requirements on mandatory element containment and placement structure relationships are given in view definitions and implementer agreements.
IfcBuildingStorey as part of a spatial structure

Figure 113 — Building storey composition

HISTORY  New entity in IFC1.0

Attribute Use Definition

Figure 114 describes the heights and elevations of the IfcBuildingStorey.

space heights

Figure 114 — Building storey elevations

Common Use Definitions

The following concepts are inherited at supertypes:

 Instance diagram

Spatial Composition

The Spatial Composition concept applies to this entity as shown in Table 32.
Spatial CompositeDescription
IfcBuildingAssignment to the building, where the building storey is a part of.
IfcBuildingStoreyAssignment to another building storey, e.g. if this building storey is a partial storey that refer to another storey.

Table 32 — IfcBuildingStorey Spatial Composition

NOTE  By using the inverse relationship IfcBuildingStorey.Decomposes it references (IfcBuilding || IfcBuildingStorey) through IfcRelAggregates.RelatingObjectIfcBuildingStorey, the referenced IfcBuildingStorey needs to have a different and higher CompositionType, i.e. COMPLEX (if the other IfcBuildingStorey has ELEMENT), or ELEMENT (if the other IfcBuildingStorey has PARTIAL).

Spatial Decomposition

The Spatial Decomposition concept applies to this entity as shown in Table 33.
Spatial PartsDescription
IfcSpaceReference to the spaces that are assigned to this storey.
IfcBuildingStoreySpatial decomposition into partial stories, if this storey is a main storey having subdivisions.

Table 33 — IfcBuildingStorey Spatial Decomposition

NOTE  By using the inverse relationship IfcBuildingStorey.IsDecomposedBy it references IfcBuildingStorey || IfcSpace through IfcRelAggregates.RelatedObjects. If it refers to another instance of IfcBuildingStorey, the referenced IfcBuildingStorey needs to have a different and lower CompositionType, i.e. ELEMENT (if the other IfcBuildingStorey has COMPLEX), or PARTIAL (if the other IfcBuildingStorey has ELEMENT).
NOTE  Multi storey spaces shall be spatially contained by only a single building storey, usually it is the building storey where the base of the space lies.

Spatial Container

The Spatial Container concept applies to this entity.

If there are building elements and/or other elements directly related to the IfcBuildingStorey (like most building elements, such as walls, columns, etc.), they are associated with the IfcBuildingStorey by using the objectified relationship IfcRelContainedInSpatialStructure. The IfcBuildingStorey references them by its inverse relationship:

Elements can also be referenced in an IfcBuildingStorey, for example, if they span through several storeys. This is expressed by using the objectified relationship IfcRelReferencedInSpatialStructure. Systems, such as building service or electrical distribution systems, zonal systems, or structural analysis systems, relate to IfcBuildingStorey by using the objectified relationship IfcRelServicesBuildings.

Property Sets for Objects

The Property Sets for Objects concept applies to this entity as shown in Table 34.

Table 34 — IfcBuildingStorey Property Sets for Objects

Quantity Sets

The Quantity Sets concept applies to this entity as shown in Table 35.

Table 35 — IfcBuildingStorey Quantity Sets

Product Placement

The Product Placement concept applies to this entity.

The local placement for IfcBuildingStorey 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.

FootPrint GeomSet Geometry

The FootPrint GeomSet Geometry concept applies to this entity as shown in Table 36.
FootPrintGeometricCurveSetIfcGeometricCurveSetSet of curves (outer and inner) representing the floor projection,

Table 36 — IfcBuildingStorey FootPrint GeomSet Geometry

The foot print representation of IfcBuildingStorey is given by either a single 2D curve (such as IfcPolyline or IfcCompositeCurve), or by a list of 2D curves (in case of inner boundaries), if the building storey has an independent geometric representation.

NOTE  The independent geometric representation of IfcBuildingStorey may not be allowed in certain model view definitions. In those cases only the contained elements and spaces have an independent geometric representation.

Body Geometry

The Body Geometry concept applies to this entity as shown in Table 37.

Table 37 — IfcBuildingStorey Body Geometry

The body (or solid model) geometric representation (if the building storey has an independent geometric representation) of IfcBuildingStorey is defined using faceted B-Rep capabilities (with or without voids), based on the IfcFacetedBrep or on the IfcFacetedBrepWithVoids.

NOTE  Since the building storey shape is usually described by the exterior building elements, an independent shape representation shall only be given, if the building storey is exposed independently from its constituting elements and such independent geometric representation may be prohibited in model view definitions.

XSD Specification:

 <xs:element name="IfcBuildingStorey" type="ifc:IfcBuildingStorey" substitutionGroup="ifc:IfcSpatialStructureElement" nillable="true"/>
 <xs:complexType name="IfcBuildingStorey">
   <xs:extension base="ifc:IfcSpatialStructureElement">
    <xs:attribute name="Elevation" type="ifc:IfcLengthMeasure" use="optional"/>

EXPRESS Specification:

ENTITY IfcBuildingStorey
SUBTYPE OF IfcSpatialStructureElement;
Elevation : OPTIONAL IfcLengthMeasure;

Link to EXPRESS-G diagram EXPRESS-G diagram

Attribute Definitions:

Elevation : Elevation of the base of this storey, relative to the 0,00 internal reference height of the building. The 0.00 level is given by the absolute above sea level height by the ElevationOfRefHeight attribute given at IfcBuilding.

Inheritance Graph:

ENTITY IfcBuildingStorey
GlobalId : IfcGloballyUniqueId;
OwnerHistory : OPTIONAL IfcOwnerHistory;
Name : OPTIONAL IfcLabel;
Description : OPTIONAL IfcText;
ENTITY IfcObjectDefinition
HasAssignments : SET OF IfcRelAssigns FOR RelatedObjects;
Nests : SET [0:1] OF IfcRelNests FOR RelatedObjects;
IsNestedBy : SET OF IfcRelNests FOR RelatingObject;
HasContext : SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions;
IsDecomposedBy : SET OF IfcRelAggregates FOR RelatingObject;
Decomposes : SET [0:1] OF IfcRelAggregates FOR RelatedObjects;
HasAssociations : SET OF IfcRelAssociates FOR RelatedObjects;
ENTITY IfcObject
ObjectType : OPTIONAL IfcLabel;
IsDeclaredBy : SET [0:1] OF IfcRelDefinesByObject FOR RelatedObjects;
Declares : SET OF IfcRelDefinesByObject FOR RelatingObject;
IsTypedBy : SET [0:1] OF IfcRelDefinesByType FOR RelatedObjects;
IsDefinedBy : SET OF IfcRelDefinesByProperties FOR RelatedObjects;
ENTITY IfcProduct
ObjectPlacement : OPTIONAL IfcObjectPlacement;
Representation : OPTIONAL IfcProductRepresentation;
ReferencedBy : SET OF IfcRelAssignsToProduct FOR RelatingProduct;
ENTITY IfcSpatialElement
LongName : OPTIONAL IfcLabel;
ContainsElements : SET OF IfcRelContainedInSpatialStructure FOR RelatingStructure;
ServicedBySystems : SET OF IfcRelServicesBuildings FOR RelatedBuildings;
ReferencesElements : SET OF IfcRelReferencedInSpatialStructure FOR RelatingStructure;
ENTITY IfcSpatialStructureElement
CompositionType : OPTIONAL IfcElementCompositionEnum;
ENTITY IfcBuildingStorey
Elevation : OPTIONAL IfcLengthMeasure;

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