Cost of adding an ADU on the second floor

[Jeff Cliff]

Hello,

I am considering adding about 1200 sqft ADU on top of existing one story single family house. A few people advised me against that because of the cost. However, because of the spectacular views I could get from this second floor I am still trying to figure out best way to put second story ADU.

Has anyone added second story on top of the existing house? What all does it entail? How much more expensive does it get?