Chapter II: The right of accession to that which unites with and incorporates into the thing

Property of the ground carries with it ownership of the land above and below. The owner may make above it all the plantations and constructions he deems appropriate, subject to the exceptions set out in the title “Of land easements or services”. He may make below it all the constructions and excavations he deems appropriate, and draw from these excavations all the products they may provide, subject to the modifications…

All constructions, plantations and works on land or in the interior are presumed to have been made by the owner at his own expense and to belong to him, unless the contrary is proved; without prejudice to the ownership which a third party may have acquired or may acquire by prescription either of an underground passage under the building of another, or of any other part of the building.

The owner of the land who has made constructions, plantations and works with materials that did not belong to him must pay the estimated value at the date of payment; he may also be ordered to pay damages, if appropriate: but the owner of the materials does not have the right to remove them.

Where the plantations, constructions and works have been made by a third party and with materials belonging to the latter, the owner of the land has the right, subject to the provisions of paragraph 4, either to retain ownership of them or to oblige the third party to remove them. If the owner of the land requires the removal of the constructions, plantations and works, it shall be carried out…

The landings and accretions that successively and imperceptibly form at the riparian bottoms of a watercourse are called “alluvium”. Alluvium benefits the riparian owner, whether the watercourse is state-owned or not; on condition, in the former case, that the footpath or towpath is left, in accordance with the regulations.

The same applies to the relays formed by running water which insensibly withdraws from one of its banks by bearing on the other: the owner of the uncovered bank benefits from the alluvium, without the riparian on the opposite side being able to come and claim there the land he has lost. This right does not arise with regard to the relays of the sea.

Alluvion does not take place in respect of lakes and ponds, the owner of which always retains the land that the water covers when it is at the level of the discharge of the pond, even if the volume of water comes to diminish. Reciprocally, the owner of the pond acquires no right to the riparian land that its water comes to cover in extraordinary floods.

If a watercourse, whether state-owned or not, removes by a sudden force a considerable and recognisable part of a riparian field, and carries it to a lower field or to the opposite bank, the owner of the part removed may claim his property; but he is bound to make his claim within one year: after that time, he will no longer be eligible, unless the owner of the field to…

Islands, islets and landings that form in the bed of state-owned watercourses belong to the public entity that owns the domain concerned, in the absence of a title or prescription to the contrary.