A 60-year-old man, who also lived in the flat, and the driver of the truck, who is 54, sustained minor injuries
Both have been taken to Inverclyde Royal Hospital.
One other man who was in the building at the time was evacuated unhurt.
Emergency services rushed to the scene of the crash at 2pm today.The ground floor of the building was seriously damaged and has been deemed structurally unsound.
The A78 has been closed in both directions between the north of Fairlie and Hunterston.
Strathclyde Fire and Rescue said a lorry had left the road and collided with a two-storey building.
The driver of the lorry has been taken to Inverclyde Royal Hospital. The driver’s condition is not known.
No other vehicle was involved.
The A78, between Hunterston roundabout and Largs, has been closed in both directions.
Drivers have been advised to take alternative routes through the B780 and B784.