Building Work Done Without a Permit: Regularize or Demolish?

An extension, a veranda, a change of use, a swimming pool: the work has already been carried out, sometimes by a contractor who assured the owner « it’ll be fine, no one checks, » sometimes on the owner’s own initiative, eager to move forward. Then comes the inspection, a neighbour’s complaint, or simply the discovery of the irregularity when the property goes up for sale. The question then becomes very concrete: can it be regularized, or is demolition a real risk?

The pain point: a structure that doesn’t officially exist

This type of case comes up frequently in our expert assessments along the French Riviera, where pressure on land pushes some owners or contractors to take liberties with planning regulations. French planning law (Code de l’urbanisme) requires a full building permit (permis de construire) for any new construction creating more than 20 m² of floor area or footprint (Article R421-1 et seq.), and a simple prior declaration (déclaration préalable) for smaller works (between 5 and 20 m², certain façade alterations, changes of use without structural work). A structure built without the required authorization constitutes a criminal offence under Article L480-4 of the Code de l’urbanisme, punishable by a fine and, in some cases, demolition of the structure.

Owners often discover this at the worst possible moment: during a sale, when the notary requires proof of planning compliance, or during an inspection triggered by a neighbour’s complaint. The structure exists physically, it may be perfectly functional, but it has no administrative existence — which blocks any transaction and exposes the owner to penalties.

Why it happens

A few scenarios come up again and again. The first is underestimating the area created: an owner believes an 18 m² extension stays under the permit threshold, without accounting for the rule that aggregates it with any surface area already added over the previous ten years, or without correctly factoring in footprint alongside floor area. The second is misplaced trust in a contractor who claims to be handling the paperwork, but never actually files anything — or files a simple declaration when a full permit was required. The third, rarer but real, is a structure built in full knowledge of the irregularity, on the gamble that no one would check.

Local planning rules also matter: the commune’s local urban plan (PLU) can impose stricter rules than general law (maximum height, ground coverage ratio, setback from boundary lines), and a structure can be irregular not because it lacks any authorization at all, but because it fails to comply with the applicable PLU — which makes regularization even more complex.

What can be done

The first step is to establish precisely the nature of the irregularity: no authorization at all, authorization obtained but work not built as authorized, or a structure that complies with the original permit but not with the current PLU. This distinction determines the strategy. If the structure complies with the planning rules currently in force but simply lacks authorization, after-the-fact regularization is possible: it involves filing, retroactively, a building permit application or prior declaration for the existing structure, demonstrating compliance with the rules applicable at the time this regularization request is filed (not the rules in force when the work was originally carried out, except in specific cases).

If the structure does not comply with the current PLU, regularization becomes far harder, sometimes impossible without altering the structure. In that case, the options are either partial compliance work (reducing the structure to meet the rules) or, as a last resort, demolition — which remains a possible sanction but is not automatic: courts weigh the proportionality of the measure against the severity of the breach and the public interest at stake. A conversation with the commune’s planning department, usually before any formal filing, generally gives a realistic read on the actual chances of regularization.

How the expert helps

In cases like this, our role is to establish a precise technical record of the existing structure: exact areas created (floor area and footprint), heights, position relative to boundary lines, materials and construction techniques used. These details, measured precisely on site, are essential to building a credible regularization file, or to objectively assessing the gaps against the applicable PLU.

We never get involved in questions of property boundaries, which fall to licensed surveyors (géomètres-experts), but we do assess the technical and structural compliance of the building: adherence to building regulations, safety, and quality of execution — a distinct question from the purely administrative one, but often intertwined with it during a regularization process. Our report can also serve to objectively value the structure in question, useful in negotiations with the commune or in disputes. With fifteen years of experience in public works and project management, we know the technical requirements that typically accompany planning regularization applications.

Frequently asked questions

Can I always regularize a structure built without a permit?
It depends on whether it complies with the planning rules currently in force. If it does, after-the-fact regularization is usually possible. If it doesn’t, regularization becomes far more complex, and sometimes impossible without modification.

How real is the risk of demolition?
Demolition remains a possible sanction in cases of serious breaches and persistent non-compliance, but it is not automatic: courts weigh proportionality based on the circumstances.

How much time do I have to regularize after discovering the irregularity?
There is no fixed deadline for starting a regularization process, but acting quickly is strongly advised, especially if an inspection or proceedings are already underway, to limit the risk of sanctions.

Can the expert help me determine whether my work required a permit?
The expert assesses the technical characteristics of the structure (areas, heights, positioning) — the details needed to determine what type of authorization was required, alongside any administrative or legal support you may need.

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📅 Mis à jour le 25/09/2026 — Cassini Expertise, expert bâtiment indépendant (06·83·13·40).