How should we add layers to a beam in Revit?

Answer 1

If the goal is to actually add something like fireproofing, it could be added by editing the family and creating it there; however, if you are not adept at family construction in Revit, you likely wouldn't want to try that.

Answer 2

Beams do not have layers in the same way that a Wall, Floor or Roof has. A structural beam is made of only its base material, Steel, Conc, Wood or other. If you are wanting to add something like fireproofing and or other materials I believe Autodesk is talking about doing this in the future for now non system families do not have layers.