Building permit: frequently asked questions
What exactly is a building permit?
A building permit is an administrative authorisation issued by the local authority that allows you to carry out major construction or development work. It ensures that your project complies with the urban planning rules in force in your area (in particular the Local Urban Plan, or PLU).
This process is mandatory in many cases, including:
- Building a single-family home
- Carrying out an extension of more than 20 m² (or 40 m² in certain cases)
- Significantly altering the external appearance of a building
- Changing the use of a building (e.g. converting commercial premises into a residence)
In short, whenever your project intentionally and permanently alters the built structure, a permit is usually required.
When do you need to apply for a building permit?
A building permit is required in many situations. Here are the most common ones:
- Building a single-family home
- Extending or raising an existing building (garage, conservatory, additional storey…)
- Building an outbuilding (garden shed, carport, covered pool…)
- Changing the use of a building (residential → professional or vice versa)
- Installing a roof window, modifying a façade
What documents are needed for a building permit?
Submitting a building permit application requires putting together a complete file, including:
- Cerfa form no. 13406*12 (individual house construction)
- A site location plan
- A block plan (showing the position of the construction)
- A cross-section plan
- Façade and roof plans
- A descriptive statement
- Photos of the plot and its surroundings
- A landscape integration view (3D rendering of the project)
All these documents must be accurate, compliant with the local urban plan, and often signed by an architect.
An incomplete application = a delayed or even rejected project.
Why hire an architect for a building permit?
Hiring an architect maximises your chances of permit approval while freeing you from the complexity of the process...
Here are the concrete benefits:
- Guaranteed compliance with regulations
- Perfectly prepared technical plans and documents
- Time saved on putting the file together
- Advice on project optimisation (budget, materials, orientation…)
- Fewer risks of rejection or changes required by the local authority
And above all, beyond 150 m², the involvement of an architect is compulsory.
What is the maximum area allowed without a building permit?
You can carry out certain extensions or constructions without a permit if they are under 20 m² (or 40 m² in urban areas covered by a local urban plan). Beyond that, a building permit is required. For garden sheds, the limit is set at 5 m² with no formalities required.
How long does it take to obtain a building permit?
The timeframe varies depending on the nature of the project and the local authority. On average, a council has 2 months to process an application for a single-family home, and 3 months for other constructions. This period may be extended if the opinion of specific bodies (such as the Architects of Historic Buildings) is required.
How much does a building permit cost?
Submitting a building permit application is free of charge. However, additional costs may apply: a development tax (calculated based on the floor area created and the local authority) and architect's fees if you choose to hire one. These costs vary significantly depending on the project.
What can be done without a building permit?
Some minor works only require a prior declaration to the local authority: an extension of less than 20 m² (40 m² in certain areas), the construction of a garden shed or an uncovered pool of less than 100 m². Simple interior renovations do not require any specific procedure.
How do you obtain a building permit?
You must put together a complete file including the Cerfa form, a site location plan, a block plan, façade and roof plans, and a descriptive statement. This file must be submitted to the local authority in person or electronically. An architect can help you prepare it correctly to avoid rejection.
When is an architect required for a building permit application?
An architect is compulsory as soon as the floor area of your project exceeds 150 m². Below this threshold, it is not a legal requirement, but it is strongly advised: an architect brings technical and regulatory expertise, which increases the chances of obtaining the permit quickly.
Do I need a building permit for a swimming pool?
It depends on the dimensions:
- Uncovered pool under 100 m² → simple prior declaration.
- Covered pool with shelter less than 1.80 m high → prior declaration.
- Covered pool with shelter over 1.80 m → building permit required.
Should I use an expert for my building permit application?
It is not a legal requirement, but it is strongly recommended. Incomplete or poorly presented files often lead to rejections or additional delays. Working with an architect helps secure your application, optimise the project design, and save time.
Can you build without a permit and regularise later?
Building without a permit is a serious offence that can lead to penalties: heavy fines, obligation to demolish or modify the construction. Regularisation is sometimes possible, but nothing is guaranteed and it depends on compliance with planning regulations. It is therefore essential to submit a permit application before any work begins.
How long is a building permit valid?
As a general rule, a building permit is valid for 3 years from the date of issue. You must therefore start work within this period. If the construction is interrupted for more than one year, the permit lapses. However, it is possible to request a one-year extension, renewable once.
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