Is there a possibility to allocate an IFCWALLSTANDARDCASE directly to built-in parts or is this only possible via the assignment to the floor (IFCBUILDINGSTOREY).
There is the Decomposition concept:
https://standards.buildingsmart.org/IFC/RELEASE/IFC4/ADD2_TC1/HTML/link/element-decomposition.htm
4.5.1.2 Element Decomposition
Provision of an aggregation structure where the element, representing the composite, is decomposed into parts represented by other elements.
The composite then provides, if such concepts are in scope of the Model View Definition, exclusively the following:
- Product Placement — the common object coordinate system to which the parts are placed relative
By default the following constraints apply to an element being decomposed by Element Decomposition:
- Body Geometry — composite is constructed from the sum of the Body Geometry of the parts;
- the composite shall not have an own Body Geometry, body geometry is provided at the parts;
- the composite shall not have an own Material assignment, material is assigned to the parts.
Or as expressed via the Composition concept:
4.5.1.1 Element Composition
Provision of an aggregation structure where the element is part of another element representing the composite. The part then provides, if such concepts are in scope of the Model View Definition, exclusively the following:
- Body Geometry — The partial body shape representation and its placement;
- Material — The material information for the part.
The part may also provide, in addition to the aggregate, more specifically the following:
- Property Sets — The parts may have individual property sets assigned, solely or in addition to the composite;
- Quantity Sets — The parts may have individual quantity sets assigned, solely or in addition to the composite.
To be able to steer this via native software shows many limitations.
E.g. ARCHICAD composite elements can become upon IFC Export a wall + parts, but the parts are strictly IfcBuildingElementPart (no control over their class). They can receive additional properties and quantities, but this is not controllable by the user (no custom propertysets for parts are possible).
But it doesn’t work for framing in the wall.
E.g. in Vectorworks, you can demand the export to generate individual parts, also with limited control by the user (it’s just a checkbox as part of the export-options for the element).
E.g. in Revit, you can work with nested and nested shared components, but they have to be created in a particular manner to get their composite structure in IFC. (e.g. by placing “dummy” geometry in the container object to have it properly exported). Otherwise, they become totally independent separate objects in the export.
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The open-source Blender program supports doing detailed decomposition of elements with control over their classes. Here is an example composite wall to a crazy amount of detail where every single brick is accounted for (or you could group the bricks, up to you):
You can see it translated here in Xbim:
or in BIMCollab:
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Thank you.
That looks good.
Can you send me the example file or upload it because I’m not so fit with Blender?
If you send me a message with your email I can email it to you.
Hello, my email address is hb@pro4D.com 
Sent to your email.
Thanks for the file. Is there a way to export an IFC file from Blender?
Both Import & Export work (but maybe in some cases have bugs which with community help will solve):
How IFC recognize surrounding environment like opening & wall support
I have made walls.separately.exported extracted providing actual dimension but I need effective dimensions which depends upon surrounding constraints like opening continuity or fixed support etc
Resuming for a quick question
@stefkeB what you write seems obvious from the POV of Elementi Composition and Decomposition, indeed e.g. the diagram https://standards.buildingsmart.org/IFC/RELEASE/IFC4/ADD2_TC1/HTML/schema/templates/element-decomposition.htm shows the composition/decomposition of every IfcElement to any other, as expressed in BB by @Moult and in GeometryGym by @jonm. At the same time, analyzing the HTML documentation, it specifies the application of these concepts just to few classes (for example IfcRoof, IfcWallElementedCase (dep), IfcBeam, IfcSlabElCase (dep)), not for IfcWall. From this POV, it seems just specific classes have the ability to be composed/decomposed.
Could we assume that the HTML documentation for those cited classes is just an old/more accurate specification, and we go ahead working on aggregate any IfcElement with any other we want?