# Leaking Drain Stack in a Shared Building: Who Pays?

> # Leaking Drain Stack in a Shared Building: Who Pays and How to Prove Liability Leak on a shared drain stack - plumber refuses to open the duct, management company denies responsi

- URL : https://cassini-expertise.fr/en/leaking-drain-stack-who-pays/
- Langue : en-US
- Mis à jour : 2026-11-02
- Site : Cassini Expertise (https://cassini-expertise.fr/)

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## Leaking Drain Stack: the Management Company Can’t Dodge Responsibility

Does your plumber refuse to open the duct housing your leaking drain stack? Does the management company pass the buck, claiming it’s a private matter? That’s a legal mistake. **The vertical stack serving the floors falls under *common property* pursuant to Article 3 of the Decree of 17 March 1967**, even if it only serves a single unit. The stakes are high: who funds the diagnostic and repair work depends on precisely identifying the leak’s location (common section vs. private branch after the connection point).

## The Legal Framework: Article 3 (1967 Decree) and Article 30 of the Co-ownership Bylaws

### Article 3 of the Decree of 17 March 1967: Ducts and Vertical Stacks = Common Property

The text leaves no room for doubt: *“Ducts and vertical stacks serving one or more sections of the building are, by way of exception to the provisions of this article, considered common property.”* This classification does not depend on how many units the stack serves. However, **the private branch begins *after* the connection to the stack**. The boundary between the shared duct and private property is legally critical.

### Article 30 §2: Emergencies Allow Protective Works Without a General Meeting

A leak that seeps into the floors below or threatens the structure is an emergency. The management company **does not need to call a general meeting** to order protective works: *“Emergency works are those necessary to address an imminent danger threatening the safety of occupants or the preservation of the building.”* Diagnostic work falls under this provision.

## How Cassini Settles the Question: Three Evidence-Gathering Methods

### 1. Dye or Smoke Testing

Injecting a liquid or gas into the stack to trace the exact path of the water. Moderate cost (€300-500), immediate results. Pinpoints the faulty common section.

### 2. Endoscopic Camera Inspection

Visual inspection inside the pipework (diameter, cracks, fittings). Reveals the exact source without any demolition. Budget: €500-800. Provides photographic documentation of liability.

### 3. Complementary Non-Destructive Investigation

Moisture readings, thermal imaging, and acoustic listening devices to detect hidden leaks. **Together, these form the expert report that identifies the exact faulty section** – this is the document that unblocks the management company and the insurers.

## Maintenance Obligations

The co-ownership association is responsible for maintaining and keeping common property in good condition (Article 10 of the Law of 10 July 1965). A leak on a shared stack cannot be blamed on the owner of the unit above unless there’s proof of a faulty act (aggressive unclogging, overload, alteration) that occurred within their private section. In cases of simple wear or a lack of maintenance on the stack: **the cost falls on the co-ownership association** and its liability insurance.

## Procedure: How to Break the Deadlock

1. **Written request to the management company** with photos and a moisture report. 15-day deadline.
2. **Formal notice** if there’s no response.
3. **Call in an outside expert** (Cassini or another recognised firm) for a non-destructive diagnostic.
4. **Send the report** to the management company and its insurer.
5. **If the management company refuses to act**: refer the matter to the civil court (expedited procedure for emergencies).

## FAQ

### Can the plumber refuse to open the duct?

Not if the management company orders it. However, an individual owner cannot force a plumber to open a duct without authorisation. Plumbers fear liability in case of hidden damage. A prior expert inspection (camera) removes that doubt.

### Can I do the repair work myself and ask the management company for reimbursement?

Very risky. The management company could challenge the quality of the work. Only a repair carried out by a professional, ordered by the association, generates an undisputed right to reimbursement.

### What if the leak comes from the private branch above my duct?

Then it’s the owner of the unit *above* who pays, not the management company. Hence the importance of the expert report: it identifies the exact location (common or private) of the leak.

### How much does an emergency Cassini expert assessment cost?

A full diagnostic (dye test + camera + report): €800-1,200, depending on access and complexity. A negligible investment compared to repair work (€5,000-15,000) and long-term damage.

## Conclusion

A leak on a drain stack is never solely the private owner’s problem. Article 3 of the Decree of 17 March 1967 makes it clear: it’s common property, meaning collective responsibility and funding by the association. Non-destructive diagnostics (dye testing, endoscopic camera) are the tools that unlock the situation and force the management company to act. **At Cassini, we cover the 06, 83 and 13 areas and concentrate on this type of expert assessment**: we offer a fast response, an indisputable report, and a solution without destructive work. Contact us before the damage gets worse.

**Cassini Expertise – Areas 06, 83 & 13**
Phone: 04 22 46 06 04
Email: contact@cassini-expertise.fr

## Related Reading

- [Mould After a Flood: Who to Call](https://cassini-expertise.fr/moisissures-salle-de-bain-apres-inondation/)
- [Bathroom Humidity: Who’s Liable](https://cassini-expertise.fr/humidite-salle-de-bain-responsabilite-bailleur-syndic-locataires-vmc/)
- [Building Expert Assessment Antibes](https://cassini-expertise.fr/expertise-batiment-antibes/)

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Source : https://cassini-expertise.fr/en/leaking-drain-stack-who-pays/