Short answer. Absent any agreement, the Code allocates each flight of stairs to the owners it actually serves. The stairs from the entrance to the first storey are kept up by all owners pro rata except the ground-floor owner; the next flight excludes the ground and first-storey owners; and so on upward, flight by flight.
What the law says
The stairs from the entrance to the first story shall be maintained at the expense of all the owners pro rata, with the exception of the owner of the ground floor
Civil Code, Article 490 — Storeys Owned Separately. Read the full provision →
The rule only fills a gap
Article 490 is a default, not a mandatory scheme. It applies only if the titles of ownership do not specify the terms under which they should contribute to the necessary expenses and there exists no agreement on the subject. Where the deeds or a contract among the owners already spell out who pays for what, those terms govern and the article stands aside. It exists for the common situation of a building whose storeys were sold off separately over the years without anyone ever settling, in writing, how the shared bones of the structure would be kept up.
Each flight is paid for by those it carries
The staircase rule follows a simple logic: a flight is maintained by the owners who need it to reach their floors, and not by those who never climb it. The stairs from the entrance to the first story shall be maintained at the expense of all the owners pro rata, with the exception of the owner of the ground floor — the ground-floor owner uses no stairs to reach his own level. The next flight, from the first to the second storey, is borne by everyone above the first floor, excluding both the ground and first-storey owners, and the pattern repeats up the building.
The truly common parts are shared by all
The stairs are only one item in the article's scheme. The parts that hold the whole building up or serve everyone are charged to everyone: the main and party walls, the roof, and other things used in common are preserved at the expense of all the owners in proportion to the value of each storey. The entrance, front door, common yard and shared sanitary works are likewise maintained pro rata. Set against that, each owner alone bears the cost of maintaining the floor of his own storey, which serves no one but him.
Check the titles before applying the default
Because Article 490 yields to whatever the titles or an agreement provide, the first step in any dispute is to read those documents rather than reach for the Code. Many buildings of this kind are today governed by a condominium regime or a deed of restrictions that assigns maintenance differently, and that instrument controls. Only where the ownership papers are silent and no agreement exists do the article's pro-rata rules step in — and even then they settle the split of cost, not the separate questions of who arranges the work or how an unwilling owner is made to pay his share.