Mini Studios in the Garden: More Living Space, but Not Without Permission

Paris – 06.08.2026: Prefabricated mini studios for private property are considered an alternative to a conventional house extension. Franceinfo reported on 6 August on small residential modules installed next to the main house. They can serve as workspaces or guest rooms, create space for relatives or offer a separate retreat. This avoids the extensive conversion of the existing building, but the project is not legally straightforward as a result.

The appeal lies in industrial prefabrication. Walls, insulation, windows and often sanitary facilities are largely produced in a workshop. On the property, transport, installation and connections to electricity, water and sewage remain to be completed. This can shorten work on site and make costs easier to calculate. Under French building law, however, such a module is not considered movable furniture.

Even structures without foundations may be subject to notification or permit requirements. Outside specially protected areas, a prior building declaration to the municipality is generally required for new buildings with more than five and no more than 20 square metres of floor or usable area. Larger modules normally require a building permit. The exact assessment always depends on the location and local regulations.

Area is therefore only one of several criteria. The municipal development plan may regulate the module’s location and height, distances from neighbouring properties, roof shape, facade design and permitted materials. Stricter requirements often apply near listed buildings, in protected landscapes or in other specially designated zones. Owners should therefore consult the development plan before placing an order and ask the town hall about the requirements for their property.

The intended use is another factor. A private office or occasionally used guest room may be assessed differently from an independent accommodation unit that is permanently occupied or rented out. The development of the property, possible utility connections and the integration of the new structure into the existing built environment must also be examined. A preliminary planning certificate can clarify which rules apply to the specific project before an investment is made.

Depending on the project, location and site plans, building elevations and other documents must be submitted for a building declaration or permit application. The module’s position, dimensions and exterior design must be clear from these documents. If permission is granted, it must be displayed on the property for projects requiring approval.

Mini studios are therefore not a permit-free shortcut to more living space. Their advantage lies in standardized production and shorter work at the installation site. Whether a model may actually be built depends on its size, use, property location and municipal building law.