Technique required by the Carrez law

The area of a privative unit is 'the area of the closed and covered floors of the building after deduction of the surfaces occupied by the walls, partitions, steps and stair-wells, sheaths, embrasures of doors and windows. It is not held account of the floors whose height is lower than 1,80 mètre' (decree 97-532 of May 23, 1997).

The calculation of the area of a privative unit thus requires:

• the checking of the exact extent of the unit in the documents of joint ownership,
• the classification of the balconies, embrasures, supports, attic, etc, on the surfaces to be included or not,
• the resolution of geometrical problems, in particular in the buildings with the irregular configuration.

The following examples illustrate the technical difficulties encountered at the time of the calculation of the area.

Example 1: triangulation of a complex room

To determine surface, it is necessary to break up this polygonal part into triangles whose surface is calculable. It is the process of triangulation. Total surface is the sum of surfaces of triangles (S1+S2+S3+S4+S5).

Example 2: units whose square footage < 8m2;

Decree 97-532 of May 23, 1997 specifies that ' the units or fractions of units of a footage lower than 8 square meters are not taken into account for the calculation of the surface [within the meaning of the Carrez law] '.

This apartment is consisted 2 privative units of joint ownership Lot1 and Lot2. As Lot2 has an area < 8m² :
- Carrez area of the apartment = S1 = 12m².

If the apartment had been made up only of one unit, then:
- Carrez area of the apartment = S1+S2 = 19m².