I vote for a global Materials System in Ressource Manager.
That will hold all Building Material Info in one Place.
That will be needed for Classes or Components of Architectural Plugin Objects or
finally IFC Export.
Things like Energos Values, Weight, Render Texture; Hatches, Fill Color, Fire withstand, ...
and lots of Custom Data fields for Prices, Manufacturer, ....
And maybe extra Multiple or Sandwich Groups of those.
And lots of Preset Libraries.
Reason :
That way we have to set these values only one time when we create Wall/Window/Door/ .... Styles.