IfcWall

Semantic definitions at the entity

Entity definition

The wall represents a vertical construction that bounds or subdivides spaces. Wall are usually vertical, or nearly vertical, planar elements, often designed to bear structural loads. A wall is however not required to be load bearing.

NOTE Definition according to ISO 6707-1: vertical construction usually in masonry or in concrete which bounds or subdivides a construction works and fulfils a load bearing or retaining function.

NOTE There is a representation of walls for structural analysis provided by a proper subtype of IfcStructuralMember being part of the IfcStructuralAnalysisModel.

NOTE An arbitrary planar element to which this semantic information is not applicable (is not predominantly vertical), shall be modeled as IfcPlate.

A wall may have openings, such as wall openings, openings used for windows or doors, or niches and recesses. They are defined by an IfcOpeningElement attached to the wall using the inverse relationship HasOpenings pointing to IfcRelVoidsElement.

NOTE Walls with openings that have already been modeled within the enclosing geometry may use the relationship IfcRelConnectsElements to associate the wall with embedded elements such as doors and windows.

There are three entities for wall occurrences:

IfcWallStandardCase used for all occurrences of walls, that have a non-changing thickness along the wall path and where the thickness parameter can be fully described by a material layer set. These walls are always represented geometrically by an 'Axis' and a 'SweptSolid' shape representation (or by a 'Clipping' geometry based on 'SweptSolid'), if a 3D geometric representation is assigned. In addition they have to have a corresponding IfcMaterialProfileSetUsage assigned.
IfcWallElementedCase used for occurrences of walls which are aggregated from subordinate elements, following specific decomposition rules expressed by the mandatory use of IfcRelAggregates relationship.
IfcWall used for all other occurrences of wall, particularly for walls with changing thickness along the wall path (e.g. polygonal walls), or walls with a non-rectangular cross sections (e.g. L-shaped retaining walls), and walls having an extrusion axis that is unequal to the global Z axis of the project (i.e. non-vertical walls), or walls having only 'Brep', or 'SurfaceModel' geometry.

HISTORY New entity in IFC1.0

Attribute definitions

#	Attribute	Type	Cardinality	Description	B
9	PredefinedType	IfcWallTypeEnum	[0:1]	Predefined generic type for a wall that is specified in an enumeration. There may be a property set given specifically for the predefined types. NOTE The PredefinedType shall only be used, if no IfcWallType is assigned, providing its own IfcWallType.PredefinedType.	X

Formal Propositions

Rule	Description
CorrectPredefinedType	Either the PredefinedType attribute is unset (e.g. because an IfcWallType is associated), or the inherited attribute ObjectType shall be provided, if the PredefinedType is set to USERDEFINED.
CorrectTypeAssigned	Either there is no wall type object associated, i.e. the IsTypedBy inverse relationship is not provided, or the associated type object has to be of type IfcWallType.

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	B
IfcRoot
1	GlobalId	IfcGloballyUniqueId	[1:1]	Assignment of a globally unique identifier within the entire software world.	X
2	OwnerHistory	IfcOwnerHistory	[0:1]	Assignment of the information about the current ownership of that object, including owning actor, application, local identification and information captured about the recent changes of the object, NOTE only the last modification in stored - either as addition, deletion or modification.	X
3	Name	IfcLabel	[0:1]	Optional name for use by the participating software systems or users. For some subtypes of IfcRoot the insertion of the Name attribute may be required. This would be enforced by a where rule.	X
4	Description	IfcText	[0:1]	Optional description, provided for exchanging informative comments.	X
IfcObjectDefinition
	HasAssignments	IfcRelAssigns @RelatedObjects	S[0:?]	Reference to the relationship objects, that assign (by an association relationship) other subtypes of IfcObject to this object instance. Examples are the association to products, processes, controls, resources or groups.	X
	Nests	IfcRelNests @RelatedObjects	S[0:1]	References to the decomposition relationship being a nesting. It determines that this object definition is a part within an ordered whole/part decomposition relationship. An object occurrence or type can only be part of a single decomposition (to allow hierarchical strutures only).
	IsNestedBy	IfcRelNests @RelatingObject	S[0:?]	References to the decomposition relationship being a nesting. It determines that this object definition is the whole within an ordered whole/part decomposition relationship. An object or object type can be nested by several other objects (occurrences or types).	X
	HasContext	IfcRelDeclares @RelatedDefinitions	S[0:1]	References to the context providing context information such as project unit or representation context. It should only be asserted for the uppermost non-spatial object.
	IsDecomposedBy	IfcRelAggregates @RelatingObject	S[0:?]	References to the decomposition relationship being an aggregation. It determines that this object definition is whole within an unordered whole/part decomposition relationship. An object definitions can be aggregated by several other objects (occurrences or parts).	X
	Decomposes	IfcRelAggregates @RelatedObjects	S[0:1]	References to the decomposition relationship being an aggregation. It determines that this object definition is a part within an unordered whole/part decomposition relationship. An object definitions can only be part of a single decomposition (to allow hierarchical strutures only).	X
	HasAssociations	IfcRelAssociates @RelatedObjects	S[0:?]	Reference to the relationship objects, that associates external references or other resource definitions to the object.. Examples are the association to library, documentation or classification.	X
IfcObject
5	ObjectType	-		This attribute is out of scope for this model view definition and shall not be set.
	IsTypedBy	IfcRelDefinesByType @RelatedObjects	S[0:1]	Set of relationships to the object type that provides the type definitions for this object occurrence. The then associated IfcTypeObject, or its subtypes, contains the specific information (or type, or style), that is common to all instances of IfcObject, or its subtypes, referring to the same type.	X
	IsDefinedBy	IfcRelDefinesByProperties @RelatedObjects	S[0:?]	Set of relationships to property set definitions attached to this object. Those statically or dynamically defined properties contain alphanumeric information content that further defines the object.	X
IfcProduct
6	ObjectPlacement	IfcObjectPlacement	[0:1]	Placement of the product in space, the placement can either be absolute (relative to the world coordinate system), relative (relative to the object placement of another product), or constraint (e.g. relative to grid axes). It is determined by the various subtypes of IfcObjectPlacement, which includes the axis placement information to determine the transformation for the object coordinate system.	X
7	Representation	IfcProductRepresentation	[0:1]	Reference to the representations of the product, being either a representation (IfcProductRepresentation) or as a special case a shape representations (IfcProductDefinitionShape). The product definition shape provides for multiple geometric representations of the shape property of the object within the same object coordinate system, defined by the object placement.	X
	ReferencedBy	IfcRelAssignsToProduct @RelatingProduct	S[0:?]	Reference to the IfcRelAssignsToProduct relationship, by which other products, processes, controls, resources or actors (as subtypes of IfcObjectDefinition) can be related to this product.	X
IfcElement
8	Tag	IfcIdentifier	[0:1]	The tag (or label) identifier at the particular instance of a product, e.g. the serial number, or the position number. It is the identifier at the occurrence level.	X
	ConnectedTo	IfcRelConnectsElements @RelatingElement	S[0:?]	Reference to the element connection relationship. The relationship then refers to the other element to which this element is connected to.
	HasOpenings	IfcRelVoidsElement @RelatingBuildingElement	S[0:?]	Reference to the IfcRelVoidsElement relationship that creates an opening in an element. An element can incorporate zero-to-many openings. For each opening, that voids the element, a new relationship IfcRelVoidsElement is generated.	X
	ConnectedFrom	IfcRelConnectsElements @RelatedElement	S[0:?]	Reference to the element connection relationship. The relationship then refers to the other element that is connected to this element.	X
	ContainedInStructure	IfcRelContainedInSpatialStructure @RelatedElements	S[0:1]	Containment relationship to the spatial structure element, to which the element is primarily associated. This containment relationship has to be hierachical, i.e. an element may only be assigned directly to zero or one spatial structure.
	PositionedFrom	IfcRelPositions @RelatingElement	S[0:1]	Indicates a constrained placement, where the ObjectPosition must match positioning defined according to the referenced positioning element.	X
IfcBuildingElement
IfcWall
9	PredefinedType	IfcWallTypeEnum	[0:1]	Predefined generic type for a wall that is specified in an enumeration. There may be a property set given specifically for the predefined types. NOTE The PredefinedType shall only be used, if no IfcWallType is assigned, providing its own IfcWallType.PredefinedType.	X

Definitions applying to Bridge View

Instance diagram

This entity is used for walls of abutments, including wingwalls and foundation walls.

Geometry is commonly descibed using extruded solids or tapered extruded solids. For circular geometry, revolved solids or tapered revolved solids may be used. For more advanced scenarios having spiral geometry, surface curve swept solids (for constant profile) or sectioned spines (for variable profiles) may be used.

Walls may aggregate rebar and rebar meshes for rebar, with exception of any reinforcing that starts at footings. (Any rebar extending from a footing into a wall is defined where it is placed, which would be within the footing.)

Walls may have voids provisioned for embedded items such as junction boxes and conduit.

Walls are typically connected to footings using an element connectivity relationship, where surface geometry may constrain the connection.

Concept usage

Object Typing

The Object Typing concept applies to this entity as shown in Table 55.

Type
IfcWallType

Table 55 — IfcWall Object Typing

Exchange
Import		O
Export		O

Quantity Sets

The Quantity Sets concept applies to this entity as shown in Table 56.

Name
Qto_WallBaseQuantities

Table 56 — IfcWall Quantity Sets

Exchange
Import		O
Export		O

Element Decomposition

The Element Decomposition concept applies to this entity as shown in Table 57.

RelatedObjects
IfcReinforcingBar
IfcReinforcingMesh

Table 57 — IfcWall Element Decomposition

Exchange
Import		R
Export		R

Surface Connectivity

The Surface Connectivity concept applies to this entity as shown in Table 58.

Type
IfcFooting

Table 58 — IfcWall Surface Connectivity

Exchange
Import		O
Export		O

Element Voiding

The Element Voiding concept applies to this entity as shown in Table 59.

Table 59 — IfcWall Element Voiding

Material Layer Set

The Material Layer Set concept applies to this entity.

The material of the IfcWall is defined by IfcMaterialLayerSet, or as fallback by IfcMaterial, and it is attached either directly or at the IfcWallType.

NOTE It is illegal to assign an IfcMaterialLayerSetUsage to an IfcWall. Only the subtype IfcWallStandardCase supports this concept.

Axis 2D Geometry

The Axis 2D Geometry concept applies to this entity as shown in Table 60.

Identifier	Type	Items	Description
Axis	Curve2D	IfcBoundedCurve	The wall axis of the wall.

Table 60 — IfcWall Axis 2D Geometry

NOTE The 'Axis' is not used to locate the material layer set, only the subtype IfcWallStandardCase provides this capability.

Exchange
Import
Export

Body SweptSolid Geometry

The Body SweptSolid Geometry concept applies to this entity.

Body AdvancedSwept Tapered Geometry

The Body AdvancedSwept Tapered Geometry concept applies to this entity.

Body AdvancedSwept Directrix Geometry

The Body AdvancedSwept Directrix Geometry concept applies to this entity.

Body Clipping Geometry

The Body Clipping Geometry concept applies to this entity.

Path Connectivity

The Path Connectivity concept applies to this entity as shown in Table 61.

RelatedElement	Description
IfcWall	Walls with equal or lower priority are connected at RelatedElement.

Table 61 — IfcWall Path Connectivity

Exchange
Import
Export

Element Voiding

The Element Voiding concept applies to this entity as shown in Table 62.

Table 62 — IfcWall Element Voiding

Exchange
Import
Export

Concept inheritance

#	Concept	Model View
IfcRoot
	Software Identity	Bridge View
	User Identity	Bridge View
	Object Ownership	Bridge View
IfcObject
	Property Sets for Objects	Bridge View
IfcElement
	Element Occurrence Attributes	Bridge View
	Product Local Placement	Bridge View
	Product Assignment	Bridge View
IfcWall
	Object Typing	Bridge View
	Quantity Sets	Bridge View
	Element Decomposition	Bridge View
	Surface Connectivity	Bridge View
	Element Voiding	Bridge View
	Material Layer Set	Bridge View
	Axis 2D Geometry	Bridge View
	Body SweptSolid Geometry	Bridge View
	Body AdvancedSwept Tapered Geometry	Bridge View
	Body AdvancedSwept Directrix Geometry	Bridge View
	Body Clipping Geometry	Bridge View
	Path Connectivity	Bridge View

Formal representations

XSD Specification

 <xs:element name="IfcWall" type="ifc:IfcWall" substitutionGroup="ifc:IfcBuildingElement" nillable="true"/>

 <xs:complexType name="IfcWall">

  <xs:complexContent>

   <xs:extension base="ifc:IfcBuildingElement">

    <xs:attribute name="PredefinedType" type="ifc:IfcWallTypeEnum" use="optional"/>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcWall

 SUBTYPE OF (IfcBuildingElement);

  PredefinedType : OPTIONAL IfcWallTypeEnum;

 WHERE

  CorrectPredefinedType : NOT(EXISTS(PredefinedType)) OR
 (PredefinedType <> IfcWallTypeEnum.USERDEFINED) OR
 ((PredefinedType = IfcWallTypeEnum.USERDEFINED) AND EXISTS (SELF\IfcObject.ObjectType));
  CorrectTypeAssigned : (SIZEOF(IsTypedBy) = 0) OR
  ('IFCSHAREDBLDGELEMENTS.IFCWALLTYPE' IN TYPEOF(SELF\IfcObject.IsTypedBy[1].RelatingType));
END_ENTITY;

 EXPRESS-G diagram

Link to this page

Item	Change	Description
IFC2x3 to IFC4
IfcWall
OwnerHistory	MODIFIED	Instantiation changed to OPTIONAL.
PredefinedType	ADDED
IFC4x1 to IFC4x2
IfcWall
PositionedFrom	ADDED

	Wand
	Wall
	Mur