IfcRoof

Natural language names
Dach
Roof
Toiture
Change log
ItemSPFXMLChangeDescription
4.0.0.0
    IfcRoof
      OwnerHistoryMODIFIEDInstantiation changed to OPTIONAL.
      PredefinedTypeXMODIFIEDName changed from ShapeType to PredefinedType.
Instantiation changed to OPTIONAL.
Semantic definitions at the entity
Entity definition

A roof is the covering of the top part of a building, it protects the building against the effects of wheather.

NOTE  Definition according to ISO 6707-1: construction enclosing the building from above.

The IfcRoof shall either be represented:

NOTE  In case of an IfcRoof being the assembly of all parts of the roof the aggregation is handled by the IfcRelAggregates relationship, relating an IfcRoof with the related roof elements, like slabs (represented by IfcSlab), rafters and purlins (represented by IfcBeam), or other included roofs, such as dormers (represented by IfcRoof).
NOTE  Model View Definitions and implementer agreements may restrict the IfcRoof being an assembly to not have an independent shape representation, but to always require that the decomposed parts have a shape representation. In this case, at least the 'Body' geometric representations shall not be provided directly at IfcRoof if it is an assembly. The 'Body' geometric representation of the IfcRoof is then the sum of the 'Body' shape representation of the parts within the decomposition structure.
HISTORY  New entity in IFC2.0.
IFC4 CHANGE  Attribute ShapeType renamed to PredefinedType.
Attribute definitions
#AttributeTypeCardinalityDescription R
9PredefinedTypeIfcRoofTypeEnum? Predefined generic types for a roof that are specified in an enumeration. There may be a property set given for the predefined types.
NOTE  The PredefinedType shall only be used, if no IfcRoofType is assigned, providing its own IfcRoofType.PredefinedType.
IFC4 CHANGE The attribute has been renamed from ShapeType and changed to be OPTIONAL with upward compatibility for file based exchange.
X
Formal Propositions
RuleDescription
CorrectPredefinedTypeEither the PredefinedType attribute is unset (e.g. because an IfcRoofType is associated), or the inherited attribute ObjectType shall be provided, if the PredefinedType is set to USERDEFINED.
CorrectTypeAssignedEither there is no roof type object associated, i.e. the IsTypedBy inverse relationship is not provided, or the associated type object has to be of type IfcRoofType.
Inherited definitions from supertypes
Entity inheritance IfcBuildingElement IfcElement IfcProduct IfcObject IfcObjectDefinition IfcRoot
Attribute inheritance
#AttributeTypeCardinalityDescriptionR
IfcRoot
1GlobalIdIfcGloballyUniqueId Assignment of a globally unique identifier within the entire software world. X
2OwnerHistoryIfcOwnerHistory? 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.
IFC4 CHANGE  The attribute has been changed to be OPTIONAL.
X
3NameIfcLabel? 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
4DescriptionIfcText? Optional description, provided for exchanging informative comments.X
IfcObjectDefinition
HasAssignmentsIfcRelAssigns
@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
NestsIfcRelNests
@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).
IFC4 CHANGE  The inverse attribute datatype has been added and separated from Decomposes defined at IfcObjectDefinition.
IsNestedByIfcRelNests
@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).
IFC4 CHANGE  The inverse attribute datatype has been added and separated from IsDecomposedBy defined at IfcObjectDefinition.
X
HasContextIfcRelDeclares
@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.
IFC4 CHANGE  The inverse attribute datatype has been added.
IsDecomposedByIfcRelAggregates
@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).
IFC4 CHANGE  The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates.
X
DecomposesIfcRelAggregates
@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).
IFC4 CHANGE  The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates.
X
HasAssociationsIfcRelAssociates
@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
5ObjectTypeIfcLabel? The type denotes a particular type that indicates the object further. The use has to be established at the level of instantiable subtypes. In particular it holds the user defined type, if the enumeration of the attribute PredefinedType is set to USERDEFINED.
X
IsTypedByIfcRelDefinesByType
@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.
IFC4 CHANGE  New inverse relationship, the link to IfcRelDefinesByType had previously be included in the inverse relationship IfcRelDefines. Change made with upward compatibility for file based exchange.
X
IsDefinedByIfcRelDefinesByProperties
@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.
IFC4 CHANGE  The data type has been changed from IfcRelDefines to IfcRelDefinesByProperties with upward compatibility for file based exchange.
X
IfcProduct
6ObjectPlacementIfcObjectPlacement? 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
7RepresentationIfcProductRepresentation? 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
IfcElement
8TagIfcIdentifier? 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
FillsVoidsIfcRelFillsElement
@RelatedBuildingElement
S[0:1]Reference to the IfcRelFillsElement Relationship that puts the element as a filling into the opening created within another element.
HasOpeningsIfcRelVoidsElement
@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
ContainedInStructureIfcRelContainedInSpatialStructure
@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. X
IfcBuildingElement
IfcRoof
9PredefinedTypeIfcRoofTypeEnum? Predefined generic types for a roof that are specified in an enumeration. There may be a property set given for the predefined types.
NOTE  The PredefinedType shall only be used, if no IfcRoofType is assigned, providing its own IfcRoofType.PredefinedType.
IFC4 CHANGE The attribute has been renamed from ShapeType and changed to be OPTIONAL with upward compatibility for file based exchange.
X
Definitions applying to Reference View

 Instance diagram


Concept usage

Object Typing

The Object Typing concept template applies to this entity as shown in Table 87.

HasTypeRelatingType
IfcRoofType

Table 87 — IfcRoof Object Typing



Property Sets for Objects

The Property Sets for Objects concept template applies to this entity as shown in Table 88.

PsetNameProperties
Pset_RoofCommon
TemplatePropertyNameValueReference
Single ValueReferenceIfcIdentifier
Enumerated ValueStatusIfcLabelPEnum_ElementStatus
Single ValueAcousticRatingIfcLabel
Single ValueIsExternalIfcBoolean
Single ValueThermalTransmittanceIfcThermalTransmittanceMeasure
Single ValueLoadBearing
Single ValueFireRatingIfcLabel

Table 88 — IfcRoof Property Sets for Objects



Quantity Sets

The Quantity Sets concept template applies to this entity as shown in Table 89.

QsetNameQuantitiesComplexQuantities
Qto_RoofBaseQuantities
TemplateQuantityNameAreaValue
Area QuantityGrossArea
Area QuantityNetArea
Area QuantityProjectedArea

Table 89 — IfcRoof Quantity Sets



Element Decomposition

The Element Decomposition concept template applies to this entity as shown in Table 90.

IsDecomposedByRelatedObjectsDescription
IfcSlabA roof may be aggregated into slabs for each face.

Table 90 — IfcRoof Element Decomposition

Geometric representation by aggregated elements

If the IfcRoof has components (referenced by SELF\IfcObject.IsDecomposedBy) then no independent geometric representation shall defined for the IfcRoof. The IfcRoof is then geometrically represented by the geometric representation of its components. The components are accessed via SELF\IfcObject.IsDecomposedBy[1].RelatedObjects. The geometric representations that are supported for the aggregated elements are defined with each element. See geometric use definition for IfcSlab, IfcBeam, IfcColumn, IfcBuildingElementPart and other subtypes of IfcBuildingElement.

Figure 134 illustrates roof placement, with an IfcRoof defining the local placement for all aggregated elements.

roof

Figure 134 — Roof placement



mvdXML Specification
<?xml version="1.0"?>
<ConceptRoot xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" uuid="1d807077-d341-4b5e-8c0a-eddbbd2eb3f6" name="IfcRoof" status="sample" applicableRootEntity="IfcRoof">
  <Applicability uuid="00000000-0000-0000-0000-000000000000" status="sample">
    <Template ref="ab903982-2926-427b-b581-0eab51030088" />
    <TemplateRules operator="and" />
  </Applicability>
  <Concepts>
    <Concept uuid="5e7e0ac3-8b31-4608-b8ee-e6017c682c54" name="Object Typing" status="sample" override="false">
      <Template ref="35a2e10e-20df-40f4-ab2f-dacf0a6744f4" />
      <Requirements>
        <Requirement applicability="export" requirement="recommended" exchangeRequirement="dcd96125-898e-4ff0-b294-eb02afe953aa" />
        <Requirement applicability="import" requirement="recommended" exchangeRequirement="dcd96125-898e-4ff0-b294-eb02afe953aa" />
      </Requirements>
      <TemplateRules operator="and">
        <TemplateRule Parameters="RelatingType=IfcRoofType;" />
      </TemplateRules>
    </Concept>
    <Concept uuid="1f0672b9-aea0-4450-9545-d58e62515468" name="Property Sets for Objects" status="sample" override="false">
      <Template ref="f74255a6-0c0e-4f31-84ad-24981db62461" />
      <TemplateRules operator="and">
        <TemplateRule Parameters="PsetName=Pset_RoofCommon;" />
      </TemplateRules>
    </Concept>
    <Concept uuid="999481d1-7027-4ea9-a4a9-2c54625dbbc3" name="Quantity Sets" status="sample" override="false">
      <Template ref="6652398e-6579-4460-8cb4-26295acfacc7" />
      <Requirements>
        <Requirement applicability="export" requirement="recommended" exchangeRequirement="dcd96125-898e-4ff0-b294-eb02afe953aa" />
        <Requirement applicability="import" requirement="recommended" exchangeRequirement="dcd96125-898e-4ff0-b294-eb02afe953aa" />
      </Requirements>
      <TemplateRules operator="and">
        <TemplateRule Parameters="QsetName=Qto_RoofBaseQuantities;" />
      </TemplateRules>
    </Concept>
    <Concept uuid="19a4b41b-a03c-4338-ae0d-05866911f643" name="Element Decomposition" status="sample" override="false">
      <Template ref="8a27c15a-c4ea-4ca9-8cce-7fbba1c9bce0" />
      <TemplateRules operator="and">
        <TemplateRule Description="A roof may be aggregated into slabs for each face." Parameters="RelatedObjects=IfcSlab;" />
      </TemplateRules>
    </Concept>
  </Concepts>
</ConceptRoot>
Concept inheritance

#ConceptTemplateModel View
IfcRoot
IdentitySoftware IdentityReference View
Revision ControlRevision ControlReference View
IfcObjectDefinition
ClassificationClassificationReference View
IfcObject
Object User IdentityObject User IdentityReference View
Object Predefined TypeObject Predefined TypeReference View
Property Sets for ObjectsProperty Sets with OverrideReference View
IfcElement
Product Local PlacementProduct Local PlacementReference View
CoG GeometryCoG GeometryReference View
Box GeometryBox GeometryReference View
Body Solid Geometry GeneralBody Geometry GeneralReference View
Body Tessellation GeometryBody Tessellation GeometryReference View
Body SweptSolid PolyCurve GeometryBody SweptSolid PolyCurve GeometryReference View
Mapped GeometryMapped GeometryReference View
Product Geometry LayerProduct Geometry LayerReference View
Product Geometry ColourProduct Geometry ColourReference View
Spatial ContainmentSpatial ContainmentReference View
Element CompositionElement CompositionReference View
Element VoidingElement VoidingReference View
Material SingleMaterial Single for Objects with OverrideReference View
Material ConstituentMaterial Constituent Set with OverrideReference View
ClassificationClassification for Objects with OverrideReference View
IfcRoof
Object TypingObject TypingReference View
Property Sets for ObjectsProperty Sets for ObjectsReference View
Quantity SetsQuantity SetsReference View
Element DecompositionElement DecompositionReference View
Formal representations
XML Specification
 <xs:element name="IfcRoof" type="ifc:IfcRoof" substitutionGroup="ifc:IfcBuildingElement" nillable="true"/>
 <xs:complexType name="IfcRoof">
  <xs:complexContent>
   <xs:extension base="ifc:IfcBuildingElement">
    <xs:attribute name="PredefinedType" type="ifc:IfcRoofTypeEnum" use="optional"/>
   </xs:extension>
  </xs:complexContent>
 </xs:complexType>
EXPRESS Specification
ENTITY IfcRoof
 SUBTYPE OF (IfcBuildingElement);
  PredefinedType : OPTIONAL IfcRoofTypeEnum;
 WHERE
  CorrectPredefinedType : NOT(EXISTS(PredefinedType)) OR
(PredefinedType <> IfcRoofTypeEnum.USERDEFINED) OR
((PredefinedType = IfcRoofTypeEnum.USERDEFINED) AND EXISTS (SELF\IfcObject.ObjectType));
  CorrectTypeAssigned : (SIZEOF(IsTypedBy) = 0) OR
('IFCSHAREDBLDGELEMENTS.IfcRoofType' IN TYPEOF(SELF\IfcObject.IsTypedBy[1].RelatingType));
END_ENTITY;

Link to EXPRESS-G diagram EXPRESS-G diagram

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