Common parts are generally considered to be parts of a building that are not for the exclusive use of one of the joint owners.
The common parts of a building, even if they are for the exclusive use of a fraction, are:
The expenses related to the payment of services of common interest may, by means of the condominium regulation, approved without opposition by a majority representing two thirds of the total value of the building, shall be borne by the joint owners in equal parts or in proportion to the respective enjoyment, provided that that duly specified and justified the criteria that determine their imputation.
The expenses related to the different flights of stairs or the common parts of the building that exclusively serve one of the joint owners are borne by those who use them.
The mandatory insurance against the risk of fire in the building, has to cover the common parts of the building. The insurance must be concluded by the joint owners; the administrator must, however, do so when the joint-owners have not done so within the deadline and for the amount that, for that purpose, has been fixed in the meeting; in that case, you will be entitled to recover the respective prize from them.