A co-owner wants to annex part of a landing, a former shared WC or a corridor to enlarge their lot. The owners’ association must then set a price, and everyone wonders what a space is worth that, on its own, can be neither let nor lived in. A ruling of the Paris Court of Appeal, commented in February 2019, concerns a borderline case: a stairwell that remained the property of the building’s former owner. It helps to distinguish common parts that have a market value from those that have none.
The legal framework
In a French co-owned building (copropriété), the common parts are those assigned to the use or benefit of all the co-owners or of several of them (article 3 of the law of 10 July 1965). Their sale is decided at the general meeting by the majority of article 26 of the same law, that is a majority of co-owners representing at least two thirds of the votes. The sale price is then shared as of right between the co-owners, in proportion to the share of common parts attached to each lot (article 16-1).
The Charte de l’expertise en évaluation immobilière (the French property valuation charter, 6th edition, November 2025) now devotes a paragraph to this question (Title III, §1.23). The value of common parts is defined as the amount for which they can reasonably be sold, to a co-owner or to a third party. It is determined from the reference market value of the element concerned, to which an objective weighting is applied, as a discount or a premium, reflecting its functional and economic usefulness for the co-ownership and for the prospective buyer. The Charte distinguishes an outright sale from the grant of an exclusive right of use, whose value remains lower.
The usual case: a common part that creates value
The most frequent example is the combination of former maids’ rooms on the top floor into a single flat. The corridor serving them, a common part, is incorporated into the new lot with the approval of the general meeting. The other co-owners often gain less traffic in the building, and a receipt shared between them.
A co-owner on an intermediate floor can likewise annex part of a landing or former shared toilets, provided this does not inconvenience the others.
The method: reason in terms of added value
The calculation is simple to state. Determine the market value of the lot after annexation, deduct the value of the lot before annexation, then deduct the costs required for the operation: land surveyor (géomètre) for the amendment to the division deed (état descriptif de division), architect where needed, managing agent’s fees, deed costs and transfer duties, connection works.
The balance is the added value the operation brings to the benefiting lot. This is the basis on which the sale price is negotiated, generally shared between the acquiring co-owner and the owners’ association (syndicat des copropriétaires). An annexed square metre is not worth the building’s average price per square metre: a windowless corridor turned into a passage or a cupboard brings less than an extra room with a window. This is precisely what the Charte’s weighting seeks to express.
And when nobody gains any added value? That is the sign that the part concerned has no market value of its own.
The borderline case: the stairwell
The ruling pits a company, former owner of the whole building, against the owners’ association. After selling the private lots, the company had remained the owner of lots corresponding to the stairwell. The association claimed €5,235 in arrears of service charges for those lots.
The first-instance judgment
The Paris regional court (tribunal de grande instance) appointed a property expert, who valued the lots at €65,000. The court then transferred the lots to the association on that basis, less the arrears and the costs of the proceedings, so a little over €58,000 to be paid to the company for a stairwell.
The association’s arguments on appeal
The association disputed that value and put forward four points:
- The stairwell is not habitable: it can be neither let nor occupied, so it cannot be valued by income or by comparison with dwellings.
- It is burdened by a right of way in favour of all the lots, which rules out any private use.
- The association itself had spent €37,325 to restore it.
- The division deed provided that the company was to transfer the remaining lots for a token euro once the division was completed.
The Court’s decision
The Court of Appeal accepted this reasoning. The undertaking to transfer for a token euro was irrevocable. The right of way, the works financed by the association and “the absence of a market for this kind of property” confirmed a token valuation.
What the ruling teaches the valuer
This decision illustrates a rule of method: before looking for a price per square metre, ask who could buy the property and for what use. Market value presupposes a willing buyer and proper marketing (Charte, Title III, §1.1). A stairwell burdened by a right of way in favour of all the lots has no possible buyer other than the association, and the association derives no additional benefit from it since it already has the use of it.
Three points of attention follow for any valuation of common parts:
- Read the deeds. The division deed, the co-ownership regulations and the easements may contain undertakings or constraints that override any market approach.
- Identify the real beneficiary. If the annexation creates no added value for any lot, the common part has no market value, whatever its floor area.
- Take account of what has already been paid. Works financed by the co-ownership on an element it does not yet own reduce by as much what it can reasonably pay.
This approach, which starts from usefulness rather than floor area, matches the Charte’s principle that valuation rests on the analysis of recent transactions involving similar properties, adjusted for differences (Title III, §2.1). When no similar transaction exists, the expert says so and explains why the value adopted is low or token.
Further reading
The Market value page presents the valuation of a lot or a fraction of a building. Two articles on the same theme complete this one: what a valuation report contains and the European Valuation Standards 2025.
What next
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