The ‘Add Beam’ tool is available for rooms that have been closed/ended and enables the addition of beams from 2 different walls, the beams can be perpendicular to the wall or at an angle.
A beam can be extended to another room
and once added a beam can act as a wall so another beam can be drawn from it or to it.
Where beams are not parallel or a single line depicting a change in ceiling height is required, the beam command can be used with a width of 0 to mark the edge(s).
Beams always need to be drawn from and to a wall or beam, in some cases beams do not always go from wall to wall, they might go from wall to a column or to mid-air. In these cases a room needs to be added to place to beam on. This room can then be removed or tidied upon export to CAD.