Please, explain briefly but as clearly as possible the scope of the rights relating (exclusively) to the apartments and the ones relating to the building or to the communal elements owned jointly.
In the condominium the right of the owner of a flat or apartment or any other unit capable of independent use is a full property right as any other exclusive property right. This right can be limited only by the contract between co-owners regolamento contrattuale, see chapter IV.
The rights on common areas are regulated by regolamento condominiale (condominium statute).
The rights relating to communal elements are regulated by Art. 1102 Civil Code: Each participant can use the common thing if he does not alter its destination and does not prevent the other participants to make also use …
But, as mentioned above, judges decisions specify exactly the content of rights on communal elements.
As an example: the owner of the top floor of a building has the right to build windows on the common roof but can not build a terrace on the same roof.