Federal Taxes: How to Handle a Duplex, Room Rental

I have a duplex, i lived in the bottom unit and had a roommate. Top unit was rented. I calculated 4% of the building was used for the room rental. I depreciated this value the last two years. He moved out last year and I moved out as well so now I'm renting the entire building.

How do I handle depreciation on the entire building now? even though I claimed 2 years worth on 4% of the building.

Thanks!

Federal Taxes: How to Handle a Duplex, Room Rental