Building permit or prior declaration in France: thresholds, delays, appeals
Depending on the floor area created and the zone in the local plan, your works need a prior declaration (déclaration préalable) or a building permit (permis de construire). Here are the thresholds, the delays and what changed with the law of 26 November 2025.
Which authorisation for which works?
The area that counts is the footprint (emprise au sol) or the floor area (surface de plancher) created, whichever is larger.
| Works | Prior declaration | Building permit |
|---|---|---|
| New building (shed, annexe, house) | 5–20 m² (no formality up to 5 m², outside protected areas) | over 20 m² |
| Extension in the urban zone (U) of a local plan (PLU) | up to 40 m² | over 40 m², or over 20 m² if the total then exceeds 150 m² |
| Extension outside zone U, or with no PLU | up to 20 m², however small | over 20 m² |
A building permit means using an architect as soon as the total floor area exceeds 150 m² (see when an architect is required). In a protected site the 40 m² threshold does not apply: an extension needs a permit above 20 m². Check with the mairie.
Processing times
- Prior declaration: 1 month, generally 2 months in a protected area.
- Building permit for a house: 2 months, 3 months in a protected area.
- Other building permits: 3 months, generally 4 months in a protected area.
The clock starts once the file is complete. The mairie has 1 month to ask for missing documents, and you then have 3 months to supply them.
Validity and extensions
A building permit or prior declaration is valid for 3 years. It lapses if works do not start within that time, or if they stop for more than a year. It can be extended twice, by one year each time, if the planning rules have not changed: ask at least 2 months before it expires; no reply within 2 months means the extension is granted.
Exception: authorisations granted between 28 May 2022 and 28 May 2024 are valid for 5 years and cannot be extended (decree of 26 May 2025).
Posting the permit on site
From the date of the decision (or of tacit approval), a rectangular panel larger than 80 cm must be displayed so it can be read from the street, for the whole duration of the works. It shows the beneficiary, the date and number of the authorisation, the type of project, the land area, the mairie's address and, where relevant, the architect's name.
Neighbours' appeals since the 2025 law
A third party has 2 months from the first day the permit is continuously displayed on site to go to the administrative court. Since the urban planning simplification law of 26 November 2025, an informal appeal to the mayor or prefect (recours gracieux) must be made within 1 month and no longer extends the deadline for going to court.
Any appeal must be notified to the permit holder by registered letter within 15 full days, and a court appeal to the mairie or prefecture as well. For 3 months, the mairie can also withdraw an unlawful permit. If the permit was never displayed, an appeal remains possible until 6 months after the works are completed, which is why careful, photographed and dated posting matters.
Allow 1 month for a prior declaration and 2 months for a house permit, then 2 months for neighbours' appeals after posting. An authorisation is usually valid for 3 years and can be extended twice by a year.
Preparing a complete file
An incomplete file restarts the clock. The basic documents for a permit are a location plan, site plan, sections and elevations, a description of the project, a view showing it in its surroundings and photographs. An architect prepares this file as part of the mission, whether a full mission or a fixed fee.
The official rules (in French) are on service-public.gouv.fr: building permit, prior declaration, third-party appeals.
Frequently asked questions
How long does a building permit for a house take in France?
2 months from a complete file, 3 months in a protected area. Then allow for the 2-month appeal period for third parties after the permit is posted on site.
Up to what size is a prior declaration enough?
Up to 20 m² for a new building or an extension, and up to 40 m² for an extension in the urban zone of a local plan (outside protected sites), unless an extension of more than 20 m² takes the total above 150 m².
How long is a French building permit valid?
3 years, extendable twice by one year if the planning rules have not changed; ask at least 2 months before it expires. Authorisations granted between 28 May 2022 and 28 May 2024 are valid for 5 years and cannot be extended.
What changed for appeals in 2025?
Since the law of 26 November 2025, an informal appeal against a permit must be made within 1 month and no longer extends the 2-month deadline for going to the administrative court.