Floor area, footprint and taxable area of a construction: what are the calculation rules?
Verified 27 November 2024 - Directorate for Legal and Administrative Information (Prime Minister)
You want to calculate the floor area, theground right-of-way or the taxable area of your construction. What are these different surfaces for? We'll explain.
Floor area
The floor surface has several functions. It is calculated by applying different deductions depending on whether the property is a house or a group building.
The floor area is used to determine the type ofcity planning authorization required for your project.
It also lets you know if you need to use an architect.
It is also used to check if your project follows city planning guidelines of your commune. This is because the local city planning plane (PLU) can set boundaries for the building surface and height.
To find out, you can contact the city planning department of your city hall.
The floor area is calculated differently between a house and a public building:
House
The floor area is the sum of the areas of all levels constructed, enclosed and covered, including the ceiling height is more than 1,80 m, calculated from the interior nude (measured from the skirting boards).
The floor area is obtained after deduction of the following areas :
- Surfaces corresponding to the thickness of the walls surrounding the doorways of doors and windows to the outside
- Voids and hoppers (spaces under stairs and elevators)
- Floor areas with a ceiling height of 1,80 m or less
- Ground surfaces for the parking of motor and non-motor vehicles (including access ramps and maneuvering areas)
- Floor surfaces of attic not suitable for housing or for professional, craft, industrial or commercial activities (for example, attic with a large frame size or a floor that cannot withstand loads).
You must also deduct the thickness of insulating materials.
Collective building
The floor area is the sum of the areas of all levels constructed, enclosed and covered, including the ceiling height is more than 1,80 m, calculated from the interior nude (measured from the skirting boards).
The floor area is obtained after deduction of the following areas :
- Surfaces corresponding to the thickness of the walls surrounding the doorways of doors and windows to the outside
- Voids and hoppers (spaces under stairs and elevators)
- Floor areas with a ceiling height of 1,80 m or less
- Ground surfaces for the parking of motor and non-motor vehicles (including access ramps and maneuvering areas)
- Floor surfaces of attic not suitable for housing or for professional, craft, industrial or commercial activities (for example, attic with a large frame footprint or a floor that cannot withstand loads)
- Floor surfaces of technical rooms necessary for the operation of a group of buildings or of a building (including waste storage rooms)
- Floor surfaces of cellars or cellars, attached to accommodation, provided that these premises are served only by a common part
- Area equal to 10% floor areas intended for housing, after deduction of the preceding points, provided that the housing is served by common internal areas.
You must also deduct the thickness of insulating materials.
To help you calculate the floor area of your construction, you can use a calculation method:
Ground right of way
Ground right-of-way has several functions. The way it is calculated is the same whether it is a house or a public building.
Ground right-of-way is used to determine type ofcity planning authorization required for your project.
It also allows you to check if your project follows city planning guidelines of your commune. This is because the local city planning plane (PLU) can set building surface boundaries.
To find out, you can contact the city planning department of your city hall.
The ground right of way is the vertical projection of the volume of your construction, all overhangs and overhangs included. Appendices such as a garden shed, a carport or a swimming pool constitute a right of way on the ground.
However, ornaments such as the reliefs on your facade and the marquises are excluded. Roofing projections in a vacuum, i.e. when not supported by posts or projections such as moldings or ornaments, are also excluded.
An uncovered outdoor parking area or terrace that is on the same level as the natural terrain and without a deep foundation is excluded from the footprint.
Taxable area
The taxable area determines the amount of your development tax. It is calculated by applying deductions.
Taxable area is a element used to calculate the development tax (TA) due for any construction, reconstruction or extension of buildings subject to city planning permissions.
The development tax is a local tax levied by the municipality, the department and, in Île-de-France, by the region.
This tax is mainly used to finance the public facilities (networks, roads) needed for future construction and development.
The taxable area is the sum of the floor areas of each enclosed and covered level, calculated from the interior surface of the facades, including attics, cellars, and parking lots. The following areas are deducted:
- Thickness of the walls surrounding the doorways of doors and windows facing the outside
- Voids and hoppers in stairs and elevators
- Floor surfaces below a ceiling height of 1,80 meters or less.
FYI
Some facilities and fittings have a flat rate value for the calculation of the VAT:
- Tent sites, caravans and mobile recreational residences
- Locations of light recreational dwellings
- Swimming pools
- Wind turbines above 12 meters in height
- Photovoltaic panels on the ground
- Parking areas.
For more information, you can contact your departmental property tax office:
Who can help me?
Find who can answer your questions in your region
For information on the city planning's procedures and regulations
Telephone administrative information - Allo Public Service
For more information on this topic, you can contact Allô Service Public.
Attention: the service does not have access to users' personal files and cannot therefore provide information on their status.
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- Service free
The informants who answer you belong to the ministry in charge of housing and city planning.
For information on taxable area and development tax
Departmental Property Tax Center (CDIF)
Defining the Floor Surface
Floor area deductions
Definition of Ground Right of Way
Definition of taxable area
Deductions from taxable area
Flat-rate value of installations and fittings
Simulator
Service-Public.fr
National Institute of Consumer Affairs (INC)
