Creating an external entrance porch: planning permit

Are you thinking of improving the entrance to your home by creating an external entrance porch (sas d'entrée)? This practical extension protects your home from the weather while creating a thermal buffer space. However, this type of alteration raises important administrative questions: is a planning permit (permis de construire) required? What steps are mandatory? The regulations change regularly, and it is essential to know your obligations before starting work in order to avoid any risk of dispute with the authorities.

The characteristics of an external entrance porch

Definition and function of the entrance porch

An external entrance porch is an enclosed space between the outside and the inside of your home. This structure can take various forms: a glazed conservatory, a masonry extension, a metal structure with transparent or opaque walls.

The porch performs several practical functions:

• Protection from the weather when the main door is opened
• Additional thermal insulation reducing energy loss
• Storage space for shoes, coats or gardening equipment
• Improvement of the appearance of the entrance to the property

Impact on floor area and footprint

Creating an external entrance porch necessarily changes the footprint (emprise au sol) and potentially the floor area (surface de plancher) of your building. The footprint is the vertical projection of the volume of the building, including all projections and overhangs.

The floor area, for its part, is calculated from the sum of the floor areas of each enclosed and covered level, with a ceiling height of more than 1.80 metres. A glazed porch of sufficient height will therefore add to the floor area.

The decisive thresholds for authorisations

The prior declaration regime

To create an external entrance porch, you will need to file a prior declaration of works (déclaration préalable de travaux) where:

• The footprint created does not exceed 20 square metres
• The floor area created remains less than or equal to 20 square metres
• Your land is located outside a protected area (secteur sauvegardé) or a listed site

This simplified procedure applies to most entrance porches of modest size. The examination period is one month from filing of the complete application. The same question of the choice between the two regimes arises for other external alterations, as our article on the pergola and the prior declaration shows.

Where a planning permit is mandatory

The obligation to apply for a planning permit to create an external entrance porch applies in several situations:

• The footprint or the floor area exceeds 20 square metres
• Your property is located in a protected area, a listed site or a site registered as a historic monument
• The works concern a building registered as a historic monument

A planning permit requires a longer examination: two months for a single-family house, three months if the land is in a protected area.

Specific features linked to local planning rules

The Local Urban Plan (Plan Local d'Urbanisme, PLU) or the planning document in force in your municipality may impose particular constraints. Some urban zones limit extensions, even modest ones, or require compliance with strict land-use coefficients.

The 2026 regulations provide for stronger environmental requirements that may affect extensions to existing buildings, in particular as regards insulation and energy performance.

Preparing and filing the administrative application

Mandatory documents for the prior declaration

The prior declaration file for creating an external entrance porch must include:

• Form Cerfa No. 13703*08, duly completed and signed
• A location plan of the land stating the scale and orientation
• A site plan of the buildings to be erected or altered
• A sectional plan of the land and the building
• A statement describing the land and presenting the project
• A plan of the facades and roofs
• A graphic document showing how the project fits into its surroundings
• A photograph showing the location of the land in the immediate surroundings and in the distant landscape

Enhanced planning permit file

If your project requires a planning permit, the file is supplemented with additional documents:

• Form Cerfa No. 13406*08 for single-family house construction
• More detailed plans including the drainage networks
• An impact study if the project is in a sensitive area
• The consent of the property manager (syndic) if you are in a co-ownership building (copropriété)

Time limits and examination procedure

The authority has a statutory period to examine your application. If there is no reply within these periods, the authorisation is deemed granted by tacit approval. However, this rule does not apply in protected areas, where express consent remains mandatory. How these examination periods are calculated and the grounds for extending them are detailed in our article on the planning permit time limit.

During the examination, the authority may ask you for additional documents, which suspends the period until they are received.

Technical and regulatory constraints

Compliance with building rules

Creating an external entrance porch involves compliance with many technical standards. The structure must meet the requirements of mechanical strength and stability defined by the standards in force.

Thermal insulation is particularly important, especially with the development of the 2026 regulations, which strengthen the energy performance required. The porch must contribute to improving the overall thermal balance of the home.

Management of rainwater

The watertightness of the porch and the drainage of rainwater are crucial technical points. The structure must incorporate an effective drainage system to avoid leaks and structural damage.

The drainage pipes must be connected to the public sewerage network or to the existing individual sanitation system, in accordance with the health regulations in force.

Accessibility and safety

If your external entrance porch is the main access to the dwelling, it must comply with the accessibility standards for people with reduced mobility. This obligation applies particularly to new buildings and major renovations.

Any electrical installations (lighting, door motorisation) must meet electrical safety standards and be the subject of a certificate of conformity.

Risks of failing to comply with the obligations

Administrative sanctions

Building an external entrance porch without authorisation exposes the owner to severe administrative sanctions. The authority may order the works to be stopped by municipal or prefectoral order.

Where a building has been completed without authorisation, a formal notice to regularise the situation may be served. If regularisation proves impossible under the planning rules, demolition may be ordered at the owner's expense. On the ways of regularising an extension built without authorisation, see our analysis of works without a permit and their regularisation.

Civil and criminal consequences

Breach of the planning rules is an offence punishable by a fine of €1,200 per square metre of floor area built unlawfully. This fine may be increased to €6,000 per square metre in the event of a repeat offence or construction in a protected site.

The courts may also order the restoration of the site at the offender's expense, together with a daily penalty payment (astreinte) for non-compliance.

Impact on the sale of the property

An irregular structure considerably complicates the sale of the property. The buyer may rely on hidden defects or demand a reduction in the sale price corresponding to the costs of regularisation or demolition.

Notaries are required to check that buildings comply with the authorisations issued, which may delay or jeopardise the property transaction.

Practical advice for the success of your project

Prior consultation with the planning department

Before finalising your project, an informal consultation with your municipality's planning department is valuable. This step makes it possible to identify the constraints specific to your land and to adapt the project accordingly.

The advisory architects of the Councils for Architecture, Urban Planning and the Environment (Conseils d'Architecture, d'Urbanisme et de l'Environnement, CAUE) also offer free advice to individuals in preparing their projects.

Choice of materials and architectural integration

Harmonious integration of the porch into the existing architecture makes it easier to obtain administrative authorisation. Favour materials and colours consistent with the main building.

The 2026 regulations favour durable materials and environmentally friendly construction solutions. This approach may have a positive influence on the examination of your application.

Anticipating time limits

The administrative time limits must be built into the planning of your project. Allow at least two months between filing the application and the earliest possible start of works, not counting any requests for additional documents.

The winter period may lengthen these time limits because of the volume of applications and administrative leave.

Regulatory developments and outlook for 2026

Strengthening of environmental requirements

The 2026 regulations are expected to be more demanding in terms of energy performance and the carbon impact of buildings. These new standards will apply gradually to extensions and major renovations.

Creating an external entrance porch will have to take account of these stronger environmental constraints, in particular in terms of insulation, ventilation and choice of materials.

Announced administrative simplification

The public authorities are working on simplifying administrative procedures for small extension projects. This approach could make the steps for creating a modest external entrance porch easier.

The gradual move to online procedures already makes it possible to file authorisation applications online in many municipalities.

Creating an external entrance porch is a practical and aesthetic investment for your home, but requires scrupulous compliance with the planning rules. The complexity of the regulations and the constant evolution of the standards, particularly with the 2026 regulations, make it essential to be assisted by competent professionals. Do not hesitate to consult a lawyer who focuses on real estate law to secure your project and avoid any administrative dispute that could jeopardise its completion.