An IfcPlate is a planar and often flat part with constant thickness. A plate can carry loads between or beyond points of support, or provide stiffening. The location of the plate (being horizontal, vertical or sloped) is not relevant to its definition. 

Plates are normally made of steel, other metallic material, or by glass panels. However the definition of IfcPlate is material independent and specific material information is handled by using IfcAssociatesMaterial to assign a material specification to the IfcPlate. 

Plates are often add-on parts. This is represented by the IfcRelAggregates decomposition mechanism used to aggregate parts, such as IfcPlate, into a container element such as IfcElementAssembly or IfcCurtainWall. 

There are two main representations for plate occurrences:

• IfcPlate with IfcMaterialLayerSetUsage is used for all occurrences of plates, that are prismatic and where the thickness parameter can be fully described by the IfcMaterialLayerSetUsage. These plates are always represented geometrically by a 'SweptSolid' geometry (or by a 'Clipping' geometry based on 'SweptSolid'), if a 3D geometric representation is assigned
• IfcPlate without IfcMaterialLayerSetUsage is used for all other occurrences of plates, particularly for plates with changing thickness, or plates with non planar surfaces, and plates having only 'SurfaceModel' or 'Brep' geometry or if a more parametric representation is not intended

• IfcExtrudedAreaSolid is required
• IfcArbitraryClosedProfileDef, IfcArbitraryProfileDefWithVoids, IfcRectangleProfileDef, IfcCircleProfileDef, IfcEllipseProfileDef is supported
• The profile can be extruded perpendicularly or non-perpendicularly to the plane of the swept profile
• The definition of the IfcMaterialLayerSetUsage, particularly of the OffsetFromReferenceLine and the ForLayerSet.TotalThickness, has to be consistent to the 'SweptSolid' representation
• The IfcBooleanClippingResult is supported, allowing for Boolean differences between the swept solid (here IfcExtrudedAreaSolid) and one or several IfcHalfSpaceSolid

The image below illustrates a 'Clipping' geometric representation with definition of a plate using advanced geometric representation. The profile is extruded non-perpendicular and the plate body is clipped at the eave. 

• IfcExtrudedAreaSolid is required
• IfcArbitraryClosedProfileDef, IfcArbitraryProfileDefWithVoids, IfcRectangleProfileDef, IfcCircleProfileDef, IfcEllipseProfileDef is supported
• The profile can be extruded perpendicularly or non-perpendicularly to the plane of the swept profile

The image below illustrates a 'SweptSolid' geometric representation. The following interpretation of dimension parameter applies for polygonal plates (in ground floor view): IfcArbitraryClosedProfileDef.OuterCurve being a closed bounded curve is interpreted as area (or foot print) of the plate. 

The image below illustrates assignment of IfcMaterialLayerSetUsage and IfcMaterialLayerSet to the IfcPlateType and the IfcPlate occurrence. 

The image below illustrates material layer usage, where:

• The reference coordinate system is the coordinate system established by the IfcExtrudedAreaSolid.Position
• The reference plane is the plane defined by the extruded profile of IfcExtrudedAreaSolid.SweptSolid. The IfcMaterialLayerSetUsage.OffsetFromReferenceLine is specified as a distance from this plane
• The IfcMaterialLayerSetUsage.DirectionSense defines how the IfcMaterialLayer's are assigned to the reference plane. POSITIVE means in direction to the positive z-axis of the reference coordinate system
• The IfcMaterialLayerSetUsage.OffsetFromReferenceLine is the distance parallel to the reference plane and always perpendicular to the base (XY) plane of the reference coordinate system. This is independent of a potential non-perpendicular extrusion specified by IfcExtrudedAreaSolid.ExtrudedDirection 0.,0.,1. A positive value of IfcMaterialLayerSetUsage.OffsetFromReferenceLine would then point into the positive z-axis of the reference coordinate system
• The Thickness of each IfcMaterialLayer is the parallel distance (measured perpendicular to the base plane). The TotalThickness of the IfcMaterialLayerSet is the sum of all layer thicknesses and in case of a perpendicular extrusion identical with IfcExtrudedAreaSolid.Depth
• The IfcMaterialLayerSetUsage.LayerSetDirection is always AXIS3
• The local placement of the wall uses the the x/y plane for the profile, and the z-axis as the extrusion direction for the wall body

This concept can be applied to the following resources:

• LoadBearing

This concept can be applied to the following resources:

• IfcPlateType

This concept can be applied to the following resources:

• IfcStructuralSurfaceMember - An idealized structural member corresponding to the plate
• IfcTask - A task for operating on the plate

This concept can be applied to the following resources:

• Pset_ConcreteElementGeneral
• Pset_PrecastConcreteElementFabrication
• Pset_PrecastConcreteElementGeneral
• Pset_PlateCommon

This concept can be applied to the following resources:

• Qto_PlateBaseQuantities

The IfcPlate, as any subtype of IfcBuildingElement, can participate alternatively in one of the two different containment relationships:

• the Spatial Containment (defined here)
• the Element Composition

The 'Surface' can be used to define a surface model of the building (e.g. for analytical purposes, or for reduced Level of Detail representation).