ArchViz - How to model corner balcony

How do I model a balcony at a the corner of a building? I do not have a clue on how to achieve it without an effort.

Desired Result
The balconies on the right side of the image. Sample image


Starting Position
Extruding does not work. Of course I could delete all faces and add them again at the inbound side. But is there a smarter way?


Thanks
Martin

‘Inset Faces’, with zero thickness and negative depth.

Best wishes,
Matthew

It is unbelievable, it works. Maybe I get some problems with UV mapping, since faces from front and right side are overlapping.
But the result looks as desired.
How does this work?


Make balcony another mesh object. Your walls will remain in top shape for further editing. U can join building and balcony after if u use arrays making more floors.