You are at a general meeting and a decision is taken that you cannot accept. Or it has been raining through your ceiling for months and the association of co-owners (ACO) does nothing. Or you learn that the syndic has started a procedure on his own initiative, and you doubt whether that is actually permitted. In an apartment building, these are not academic questions — there, legal precision makes the difference between protecting your rights and letting them tacitly evaporate.
This pillar gives you the framework: who the ACO is, what it may decide, which majorities apply, who can contest a decision and within what period, who can sue, and what you can do yourself when the ACO remains inactive.
What is an ACO and where does its competence end?
The association of co-owners arises by operation of law as soon as a building is divided into private and common parts and the first lot is transferred (art. 3.84 NCC). From that moment, there is a legal person, with a CBE number, and a legal obligation to organise a general meeting and appoint a syndic as soon as there are at least two lots belonging to different owners (art. 3.90 NCC).
The ACO has a deliberately limited object: the conservation and management of the common parts. Nothing more. This speciality sounds self-evident, but it is regularly stretched in practice — often by property developers who want to retain their grip on a freshly accepted building.
The Ghent Court of Appeal ruled on 9 November 2017 in a file where the base deed of an industrial building to be renovated contained a "renovation clause": the future buyers would, together with the seller, bear the costs of the renovation. The court made short work of it: developing a building, including its full reconversion, falls outside the legal speciality of the ACO. In addition, the court qualified the construction as circumvention of the Breyne Act and pointed to a flagrant breach of the notaries' duty of information and advice. One cannot therefore contractually make the ACO a client (maître d'ouvrage).
That same reasoning underlies the case law of the Council for Permit Disputes which holds that an ACO has no interest to act in lodging an objection against an environmental permit of a neighbouring parcel. Read our analysis of the clause promoteur for the effect of this principle on arrangements the developer had inserted in the base deed.
The general meeting: who decides with which majority?
The general meeting (GM) is the decision-making organ of the ACO. Articles 3.87 and 3.88 NCC regulate who has the right to vote and which majorities are required. The law distinguishes four majorities, and whoever confuses them opens the door to an annullable decision.
The simple majority suffices for daily management: approving the accounts, discharge of the syndic, small maintenance decisions. The two-thirds majority is required for works to the common parts (art. 3.88 § 1, 1°). The four-fifths majority is needed for acts of disposition, statutory amendments that revise the allocation of charges, changes of destination and construction works to private parts for economic or technical reasons at the request of the ACO (art. 3.88 § 1, 2°). Unanimity is needed when the shares in the co-ownership themselves are modified (art. 3.87 § 3 NCC).
The Court of Cassation, on 9 March 2023, added an important nuance to the four-fifths majority for acts of disposition. Such a decision touches on the property right of the minority and must therefore pass the proportionality test of article 1 of the First Additional Protocol to the ECHR: a fair balance between the general interest and the protection of the peaceful enjoyment of property. A decision to limit letting to non-residents therefore requires thorough motivation — "it bothers us" does not suffice, even if one formally reaches the 4/5.
A second point of attention is the duty of abstention of article 3.87 § 9 NCC. A co-owner who is also a representative or service provider of the ACO may not vote on decisions concerning his mission. The justice of the peace of Zandhoven decided on 15 May 2023 that this rule also applies to voting by proxy: the representative cannot therefore do, via obtained proxies, what he may not do personally.
A third nuance is the de facto majority for maintenance. The justice of the peace of Hasselt I ruled on 18 April 2023 in a file where a co-owner requested the removal of an installation placed without authorisation. 68% voted against the removal. That two-thirds against was interpreted by the judge as a two-thirds majority in favour of maintenance — exactly the majority required to authorise the installation after all (art. 3.88 § 1, 1° NCC). For anyone seeking a removal, this means: formulate the question put to the vote carefully. Our article on acts of disposition and the 4/5 majority examines these majority rules and the ECHR test in detail.
The syndic: executive, not decision-making
The syndic is not a decision-maker but an executive organ that concretises the decisions of the GM and carries out the daily management. Articles 3.89-3.90 NCC make his appointment obligatory as soon as the building counts two lots belonging to different owners. The omission has direct procedural consequences: an action concerning the common parts cannot be validly introduced as long as the ACO is not validly represented in court (J.P. Ostend I, 19 December 2023).
In default, any interested party can ask the justice of the peace to appoint a syndic by unilateral petition (art. 594, 21° Jud. C.). Two figures are often confused: the judicial syndic is appointed in case of complete default, by unilateral petition; the provisional syndic acts alongside or in place of a sitting syndic who remains in default, and is appointed on an adversarial basis (art. 3.89 § 8 NCC). The justice of the peace of Ganshoren held on 21 April 2023 that a GM that has meanwhile met does not undo the lack of correct management — the request for a provisional syndic remains possible.
The syndic may not transfer his competence just like that. The justice of the peace of Antwerp 6 ruled on 27 October 2021 that a syndic who had his tasks carried out by an employee without IPI accreditation was in breach of article 3.89 § 6 NCC. That article only allows transfer subject to express GM authorisation and for a limited duration or well-defined purposes. Consequence: the decisions of that GM were annulled and a provisional syndic appointed.
Finally: an outgoing syndic must transmit the complete file, including digital — a legal, contractual and deontological obligation (Court Brussels, 19 June 2023). Our article appointing, replacing or making the syndic disappear examines how you enforce this in practice.
When can a co-owner contest a GM decision?
The answer begins with a date. A co-owner who believes that a GM decision is irregular or abusive has a forfeiture period of four months from the date of the general meeting to have it annulled before the justice of the peace (art. 3.92 § 3 NCC). Forfeiture period means: after four months, the right is irrevocably gone. No interruption, no suspension, no extension.
What is a contestable decision? The justice of the peace of Ostend I made on 10 October 2023 a fine distinction. An irregular decision violates the law or the statutes — materially (excess of competence of the GM, wrong majority) or formally (defects in the convocation letter, the agenda item, the minutes). An abusive decision, by contrast, is legally and formally correct, but disproportionate on the substance: the majority chooses a solution that harms the minority disproportionately while better alternatives exist, or the decision is driven by subjective rather than objective motives.
For both grounds, the claimant must demonstrate his interest (art. 8.4 NCC): what concrete prejudice does he suffer from the contested decision? Without interest, no action. That same court added that it is the judge, not the GM, who decides sovereignly on questions of qualification. A GM cannot therefore itself bindingly decide that a certain activity (e.g. a commercial operation) does or does not fall under the statutes.
For anyone wanting to know precisely which grounds of annulment play in which situations, we have developed the irregular versus abusive ACO decision in a separate article.
Who can sue — the ACO, the syndic or the co-owner?
Standing to sue in co-ownership is layered. Whoever thinks that only the ACO via its syndic can sue overlooks an important escape.
Article 3.92 § 1 NCC grants the ACO its own standing to sue to defend the common interests — as claimant or defendant, whether or not together with individual co-owners. The enterprise court of Antwerp, Hasselt division, ruled on 22 March 2023 in a water infiltration file that this standing to sue is non-exclusive. An individual co-owner who suffers water damage in his lot can himself sue the property developer, the contractor or the architect for his share in the co-ownership — even when the cause lies in the common parts and even if the ACO does not cooperate. The in-depth analysis is in the article standing to sue of the ACO, the syndic and the co-owner.
The syndic himself may, on behalf of the ACO, bring urgent actions or conservatory measures without prior GM mandate, subject to later ratification (art. 3.92 § 1 NCC). The justice of the peace of Sint-Jans-Molenbeek allowed on 13 June 2022 that the syndic claim, on behalf of the ACO, the eviction of a tenant for particularly serious nuisance — the ACO may therefore also act against tenants who undermine the common enjoyment.
For the costs: article 3.92 § 9 NCC provides that a co-owner whose action against the ACO is declared entirely founded is exempt from his contribution to the fees and costs — these are distributed over the other co-owners. The same applies to a co-owner who is sued in an action that later proves unfounded (J.P. Genk, 13 February 2024). In case of partial foundation: proportional intervention of the ACO.
Works in and to the building: common versus private
A recurring point of contention is who may carry out what — and who pays. The distinction between private and common parts seems simple, but the dividing line often runs through materials, conduits or installations that touch on both.
Permanent constructions on common parts always require prior GM authorisation, even with an exclusive right of use. The justice of the peace of Hasselt I ruled on 24 October 2023 in a file where an owner had placed on his roof terrace a veranda-like canopy of 19 m² with support posts, glass sliding doors and gluing on the roof. The exclusive right of use allows placing tables, chairs and parasols — not erecting permanent constructions. The roof remains common, the appearance of the building changes, and de facto a part of the common area is privatised. Without GM authorisation: unlawful.
Modification works to private parts that influence the appearance of the building or cause noise nuisance fall under the notification procedure of article 3.82 NCC. The owner must communicate his intention in writing to the syndic, who places it on the agenda of the next GM. This has become the battlefield of the energy transition: heat pumps, air conditioners with outdoor unit, charging stations and solar panels are all requested or refused under this procedure.
The case law is not univocal. The justice of the peace of Brasschaat refused on 7 February 2022 an air-conditioning installation due to visual and acoustic impact. Ostend II rejected on 25 May 2022 a heat pump due to a preference for a collective heating solution. But Wavre annulled on 6 August 2021 the refusal of a heat pump because high electricity prices suffice to demonstrate a personal prejudice. For the complete picture of what falls under the notification procedure, consult the article modification works and the notification procedure.
The exclusive right of use itself — when it arises, what it permits, when it lapses — we examine separately in exclusive right of use on common parts. Important nuance there: an exclusive right of use inscribed in the base deed linked to a specific function (e.g. hotel operation) lapses as soon as that function disappears (J.P. Ostend I, 19 December 2023, hotel conversion).
The clause promoteur: limitations from the past
Property developers often have clauses inscribed in the base deed that prolong their grip on the building — practical provisions, possibilities to unilaterally amend the base deed, or exclusion of certain costs for unsold lots. Three recent rulings have firmly contained this "clause promoteur".
The justice of the peace of Hasselt I handled on 14 February 2023 a file where a co-owner relied on an authorisation from the developer to run air-conditioning conduits through common ceilings and shafts. The judge rejected this: the developer does not have the GM's competence to derogate from the co-ownership by-laws. Pursuant to article 3.93 NCC, the statutes are opposable to all holders of a real or personal right — a seller-developer can therefore not grant an opposable authorisation that circumvents the law or the by-laws.
Also important is article 3.100 NCC: the provisions of co-ownership law are of mandatory law. Contractual derogations that hollow out the legal regulation are null. The justice of the peace of Genk applied this on 13 February 2024 explicitly to attempts to circumvent the syndic's duty of information upon transfer (art. 3.94 NCC) or the notary's duty of retention (art. 3.95 NCC).
The consequences for practice are considerable. Authorisations that buyers received from a developer at the time — for air conditioning, terrace canopies, window profiles, parking signs — are on shaky ground as soon as the ACO pronounces on them. Our in-depth analysis of the clause promoteur treats the cumulative grounds on which these clauses fall.
Construction disputes and the transition to construction law
A final layer the ACO bumps into: construction defects after acceptance. Here, co-ownership law and construction law cross each other, and the consequences for the co-owners are substantial.
The ACO can directly hold the property developer, the architect or the contractor liable for construction defects to the common parts, even without a direct contractual link. The enterprise court of Antwerp confirmed on 3 November 2022 that the ACO acts as legal successor in the rights of the individual co-owners for the management and disposition of the common parts. The court moreover held that an exoneration clause whereby the developer limited his liability for minor hidden defects to one year after provisional acceptance was null. Three cumulative grounds support this nullity — our article on exoneration clauses in property developer agreements develops this.
If the ACO remains inactive, an individual co-owner is not powerless. The justice of the peace of Hasselt I condemned on 27 April 2021 a passive ACO to the execution of works to the common parts, under penalty payment, at the request of an individual co-owner. This was the starting point for the article inactive ACO facing construction defects.
The hinge between co-ownership law and construction law is moreover attached to a specific date. The Court of Cassation held on 2 September 2021 that the charges of the building only pass from the property developer to the ACO at the provisional acceptance of the common parts. Until that moment, the developer pays. For anyone wanting to know how the off-plan purchase, the constitution phase and the first GM interlock, we have written the article apartment purchase under the Breyne Act — your rights in the constitution phase of the ACO.
What to do when things go wrong?
The ACO manages your building, but its functioning is far from flawless. The four-month forfeiture period runs inexorably. A wrong majority on a sensitive decision has major consequences. A passive syndic lets damage worsen. A clause that seemed reasonable at the time can today limit your rights.
Whoever is confronted with a decision that does not hold up, a syndic who does not do his job, or an ACO that remains inactive while the building deteriorates, is well advised to seek legal advice quickly. The deadlines are short, the burden of proof technical, and the right procedural choice often makes the difference between winning and bearing the costs yourself. Get in touch via info@reius.be or the contact form for a first evaluation of your file.
In re. In jure — Rigorous in the facts. Considered in law.
Want to learn more? Also read about partial associations in large complexes and the scope of the apartment law.