3. Floor plan design new single-family house 220 sqm 2 full floors rooftop terrace

Well, this "extension" with a proper roof.

Oh, this extension is actually a projection (risalit), and overall we have here a cross-gable with a captain's gable (which in my opinion does not fit the strict design of the OP).

See it like 11ant. I wouldn’t like such a roof on the bay window; to my taste, it doesn’t fit with the otherwise straight-lined, purist look.