Leaks Between Stacked Floors: Who Pays for the Damage

When water passes from the upper apartment to the lower one through the slab separating them, the first question is to establish the cause, because who pays depends on it. If the leak arises from a fault in the common structure of the slab attributable to no one, the cost is shared under Article 1125 of the Italian Civil Code. If instead it comes from the conduct or a system of one of the two owners, whoever caused the damage is liable. Identifying the stretch and the cause is the decisive step, usually with a technical assessment.

The interfloor slab is common to the two neighbours

The slab dividing two stacked units does not belong to the condominium as a whole, but to the two neighbouring owners, following the logic of Article 1125. Its load-bearing structure belongs to both in equal parts, while the flooring is the upper owner's and the ceiling plaster the lower owner's. This joint ownership explains why, when the slab's deterioration is objective and without fault, the structural cost is split in half between the two, regardless of the thousandths (millesimi).

Leak from an objective cause: Article 1125 applies

If the slab fails or deteriorates because of wear, age or an original defect, without the event being attributable to the conduct of one of the two owners, the structural restoration work is shared in equal parts between the upper-floor owner and the lower-floor owner. Each then bears the restoration of their own finish: the flooring for the one above, the plaster and paint of the ceiling for the one below. This is the full application of the three-level criterion of Article 1125.

Leak from a culpable cause: whoever causes it pays

Equal sharing applies only if the need for the repair is attributable to no one. When instead the leak comes from negligent conduct, for example a neglected private pipe in the upper apartment, a broken system, badly executed works or an unmaintained waterproof membrane, Article 1125 does not apply but the general principle of liability: whoever caused the damage compensates for it in full. In that case the cost is neither a condominium expense nor split in half, but falls entirely on the responsible party.

• Objective slab cause without fault: structure split 50% between the two, finishes to each under Article 1125.
• Private system or conduct of the upper floor: that owner is fully liable.
• Failure of a common pipe crossing the slab: the condominium is liable as custodian.
• Damage to the lower apartment's property: compensation borne by whoever caused the leak.

When a common pipe is involved

Not all leaks between floors come from the slab or a private system. If what leaks is a common stack or pipe running through the slab or the cavity, liability falls on the condominium, custodian of the common asset under Article 2051 of the Italian Civil Code, and the cost is shared among all owners through the thousandths. This is why the technical assessment must establish precisely whether the leak comes from the slab, a private system or a common pipe: the classification completely changes who must pay.

Establishing the cause

Before allocating costs or rejecting a compensation claim, the origin of the leak must be established. The typical tools are a technician's inspection, thermography, tightness tests or video inspection of the pipes. In case of dispute between the two owners or with the condominium, a technical opinion is often needed, including through a preventive technical assessment. Documenting the cause is essential: without a reliable diagnosis, every allocation is exposed to challenge.

The manager's role

The condominium manager must handle the assessment phase when a common part is involved, coordinate the technicians and, if liability is the condominium's, activate any comprehensive building insurance policy. When instead the damage is between two private parties, their role is more limited, but it remains useful for them to help distinguish the common part from the private one to avoid wrong charges. Documented management of surveys, communications and resolutions reduces litigation.

To track claims, leaks, surveys and liability for each unit and common part, orderly management software makes the difference. With AmministraPro you can record claims, archive surveys, link them to policies and set the correct allocations under Article 1125 or the thousandths: the features are described on the /funzioni page and the plans on the /prezzi page.