A floor or apartment is the part of a building or floor, together with its components and the cubic space within it, which is technically enclosed by walls or other building elements so as to be clearly separated from the other (divisible or indivisible) parts of the building and thus constitutes an independent part of it, suitable for separate and independent residential use in general.
Only floors and floor apartments, as well as basements and rooms under the roof that are equated with floors by law, may be subject to horizontal ownership.
Therefore, it is not possible to establish divided ownership of open space, unless provided for in the (registered) constitutive act or on the basis of (registered) subsequent agreement of all parties that this space is to be rebuilt by granting an independent right of ownership over the future floor or floors, in which case the establishment of divided ownership refers to the future floors or floor apartments and is subject to Article 201 of the Civil Code, under the suspensive condition of their construction.
Until the right to build on the existing roof of the building is exercised, it remains a common area which provides the right of joint use to all floor owners and in no case does the right of elevation grant the beneficiary the power of exclusive use of the uncovered roof prior to the covering of the uncovered area for the realization of the future floor.
With the implementation of the right to build upwards (addition of a floor), the new floor becomes the exclusive property, possession, and ownership of the beneficiary of the extension, along with the corresponding percentage of compulsory co-ownership of the land and other common and shared parts of the building.
The right to extend the building upwards (height) by adding new floors belongs jointly to all co-owners of the land.
The space intended for reconstruction is not characterized as an object of ownership but as an exploitable asset for the exercise of the right of extension (height), which is provided as a consequence of the powers arising from the right of ownership or co-ownership.
It may be agreed in the deed of establishment of floor ownership that the right of height belongs to one or more of the co-owners of the land, but even in this case, the right of height appears as a consequence of the existing right of co-ownership, otherwise it is a power inherent in the right of co-ownership of the beneficiary on the land.
Thus, this specific right is not understood as a right of ownership but as a power of all or some of the co-owners, as agreed by the parties, deriving from their right of ownership or co-ownership of the land on which the existing building stands.
This right (of extension), which is transferable to a third party who is not a floor owner, is autonomous and independent of the existing horizontal properties.
