Kalispera !
I am not sure if it's the same anymore.....but, I am assuming you've been to Greece......you will have noticed many houses with flat roofs and spikes sticking out the top, well once upon a time this was done so the the family could grow up and add additional floors to the property and only pay one tax, when a roof was finally put on !
Like I say it may well have changed now, but I reckon if you've got a roof buying a resale should not be any worse than buying a new build.
Nance.