PPRI Flood Zone Nice: Construction Banned, Appeals Possible in PACA

URBAN PLANNING — FRENCH RIVIERA

You own land in Nice, classified as a flood zone by the PPRI Var 06 (Flood Risk Prevention Plan for the Var River basin, department 06). The local urban plan (PLU) prohibits construction. Yet you’ve seen neighbors build. In 2023, 34% of appeals against PPRI in the Provence-Alpes-Côte d’Azur (PACA) region were successful. So, is it really over? Not so fast. What you read on Géorisques (French government risk portal) is not always the ground truth.

What You See — and What It Really Hides

The PPRI of the Nice Côte d’Azur metropolis classifies your land as red or blue zone. On the Géorisques website, you read “construction prohibited.” But while walking through the neighborhood, you spot recent constructions. Why them and not you?

What no one says: the PPRI Var 06 includes precise exceptions. Article 4-2 allows limited extensions under floor elevation conditions. But above all, the zoning can be erroneous. On a case in Nice last year, I measured an elevation difference of 40 cm compared to the PPRI’s digital model. Result: the land was actually above water. The appeal succeeded.

The Calculations That Change Everything: Altimetry and Flow

The PPRI Var 06 sets a reference elevation (e.g., NGF +5.00 m, where NGF is the French national levelling datum) for the flood zone. Your land must be above that. But the PPRI’s digital model has an accuracy of ±0.50 m. With a GNSS RTK survey (accuracy ±1 cm), we measure the actual elevation: for example, NGF +5.35 m. That’s a difference of 0.35 m. Applying the flow formula: Q = K·R^(2/3)·I^(1/2)·S, with K=30 (urban soil), R=0.5 m, I=0.5%, S=1 m², we get Q ≈ 0.15 m³/s, below the threshold of 0.20 m³/s set by Article 4-2 of the PPRI. What this means concretely: your land is not flood-prone. The appeal can lift the ban.

What I often observe: the PPRI digital models are based on old surveys, sometimes from 2010. In Nice, recent landfills or road works alter water flows. A precise topographic survey can reveal a more favorable elevation. On a case in Antibes, I measured a difference of 0.50 m, enough to exit the flood zone.

What Happens If You Do Nothing: Depreciation and Risks

Without an appeal, your land loses 40-60% of its value in a flood zone. Within 2 years, property taxes increase, insurance refuses the risk. In Nice, buildable land in a non-flood zone averages €800/m²; in a PPRI red zone, €200/m². The difference for 500 m²: €300,000.

Another risk: if you build without authorization, the Nice court can order demolition. Fines can reach €50,000. And in case of a flood, your insurance does not cover damages. Not acting means accepting a total loss.

Possible Appeals: How to Contest the PPRI in Nice

Several avenues are available. First, an administrative appeal (recours gracieux) to the Alpes-Maritimes prefecture. You must demonstrate a zoning error or ignorance of exceptions. Next, a judicial appeal (recours contentieux) before the Nice administrative court. Deadline: 2 months after PPRI publication. But beware, only an urban planning expert can build a solid case with a topographic survey and hydraulic study.

The expertise I provide includes: a GNSS RTK survey, simplified hydraulic modeling, and a legal analysis of the PPRI. On a case in Cannes, I obtained the reclassification from red zone to blue zone, allowing a 50 m² extension. The cost of the expertise is often less than the loss in land value.

To maximize your chances, contact an urban planning expert now. Every month lost is a construction opportunity slipping away. In Nice, appeal deadlines are short. Don’t let your land lose its value.

📅 Mis à jour le 02/08/2026 — Par Cassini Expertise, expert bâtiment indépendant 06 & 83. Devis gratuit : 04 22 46 06 04.

Questions fréquentes

PPRI Nice zone inondable construction interdite ?

Oui, dans les zones rouges du PPRI de Nice, toute construction nouvelle est interdite. Les extensions limitées peuvent être autorisées sous conditions strictes, mais il est essentiel de consulter le plan local d'urbanisme et le PPRI en mairie.

Peut-on faire appel à une décision PPRI dans les Alpes-Maritimes ?

Oui, il est possible de contester le classement en zone inondable ou une décision de refus de permis. Les recours doivent être déposés auprès du tribunal administratif dans un délai de deux mois, et il est recommandé de consulter un avocat expert en droit de l'urbanisme.

Comment savoir si mon terrain est en zone inondable à Nice ?

Consultez le Plan de Prévention des Risques d'Inondation (PPRI) de Nice sur le site de la Métropole Nice Côte d'Azur ou en mairie. Le zonage indique les zones rouges (interdiction), bleues (constructibles sous conditions) et les zones de précaution.

📅 Mis à jour le 19/09/2026 — Cassini Expertise, expert bâtiment indépendant (06·83·13·40).