"Buildable" is a bit like "sea view": it all depends on what lies behind it.
"Buildable" does not mean "buildable for anything". Before setting a price or promising a building plot, you need to know how to read the local urban plan. Here is a simple method to see clearly.
1. Find the right document
Most towns have a PLU (local urban plan), increasingly drawn up for several towns together (PLUi). Some small towns have a simpler municipal map; others have no document and apply the national planning rules, which limit building to areas that are already built up.
The easiest way: the Géoportail de l'urbanisme (geoportail-urbanisme.gouv.fr). Enter the address of the land, click on the plot: the zoning and applicable documents appear. The town hall's planning department can also help.
2. Identify the zone
- U zones (urban): buildable, the networks exist.
- AU zones (to be urbanised): buildable if the zone is open (often marked 1AU), usually as part of an overall development; a 2AU zone stays closed until the plan is amended.
- A zones (agricultural) and N zones (natural): very limited building, reserved for specific cases (farming, a measured extension of an existing house…).
A large plot in a U zone can take several houses… or only one, depending on the siting rules.
3. Read the rules of the zone
Each zone has its written rules. The points that matter to know what can be built:
- the buildings allowed or prohibited;
- the maximum footprint and height;
- the position relative to the road and to the boundaries;
- the share of land to be kept as open ground or green space;
- the parking required;
- the conditions of access and connection to the networks.
Since the ALUR Act (2014), the floor-area ratio and minimum plot size have disappeared: it is these rules combined that determine the real potential. A large plot in a U zone can thus take several houses… or only one, depending on the siting rules.
4. Check the additional "layers"
Zoning does not tell the whole story. You also need to look at:
- the development and programming guidelines (OAP), which can impose an overall layout on an area;
- the public-utility easements: historic monument perimeters, power lines, pipelines, water catchments;
- the risks: flood prevention plans, ground movements, clay shrinkage and swelling (georisques.gouv.fr);
- the land reserved for the town (road widening, public facilities).
5. Apply for a planning certificate
For an official answer, apply for a planning certificate. The information certificate (CUa) states the applicable rules and taxes, within one month. The operational certificate (CUb) says whether your specific project is feasible, within two months. In both cases, the rules are frozen for 18 months, which protects your project or your sale from a change in the plan.
6. Think "buildable" in practical terms
Land can be buildable on paper but difficult to build on: steep slope, narrow access, distant networks, clay soil, no mains sewer requiring an individual system. These constraints do not make a sale impossible, but they weigh on the price and must be anticipated.
Why not wait
The 2021 Climate and Resilience Act sets a "zero net land take" target, with a sharp reduction in the use of natural land by 2031. Local plans are gradually being revised accordingly: land that is buildable today may be reclassified tomorrow. A planning certificate secures the situation while you sell.
Our approach
We do this reading for you, free of charge: zoning, rules, constraints, then what it means in practice in number of plots and value. Answer within 48 hours.
Frequently asked questions
Where can I consult my town's local plan?
On the Géoportail de l'urbanisme (geoportail-urbanisme.gouv.fr), by searching for the address or plot, or at the town hall's planning department.
What is the difference between a CUa and a CUb?
The CUa gives information on the rules and taxes applicable to the land (answer within one month). The CUb states whether a specific project is feasible (answer within two months). Both freeze the rules for 18 months.
Can land in an A or N zone become buildable?
Only if the town or group of towns amends or revises the plan. With the zero net land take target, such openings to development are rare today.
Sources: Code de l’urbanisme, article L. 410-1 (certificat d’urbanisme, règles figées 18 mois) · Loi n° 2014-366 du 24 mars 2014 « ALUR » (suppression du COS et de la surface minimale) · Loi n° 2021-1104 du 22 août 2021 « Climat et résilience » (zéro artificialisation nette) · geoportail-urbanisme.gouv.fr · georisques.gouv.fr
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