INQ: Revit family with more than one material layer

### Inquiry description

Hello,

is there a way to export more than one material as an IFC element that displays each material as a material layer?
Is there a family category and an ifc-entity which support this case?

I have built a multi-layered element for us using different materials because there is no simple function for the base wall that allows the layers to protrude differently. In X and Z direction! We need a prefabricated sandwich wall.
My solution was therefore to build my own family as a structural framing and define it as an IfcWall. Unfortunately, only one material is ever output as a “material layer.”

### Revit Version

2024.3.x

### IFC for Revit Addon Version

24.3.2

### Windows Version

11 24H2

Start by reproducing the export in Revit 2024.3.x with IFC for Revit 24.3.2 using the described structural-framing family mapped to IfcWall. Check whether the resulting IFC contains one material or multiple material layers; done should establish the supported family/entity combination or define the required implementation scope.

Written by the indexing model from the issue text.