Instructions are provided below so that the applicant can make an initial calculation of living and net habitable spaces.
See also the guide : how to calculate the TSA (total surface area) (format PDF - 78.7 kb).

Living space (SHOB)

SHOB : Surface Hors Oeuvre Brute

This consists in the sum of surface areas on each story and includes:
  convertible or non-convertible loft and basement spaces
  inaccessible terraces forming the roof,
  the thickness of walls and partitions.

Nevertheless, surfaces corresponding to the following are not counted :
  stairs
  ground floor terraces
  holes in the floor (stairway opening, lift...).

Net Habitable Space (SHON)

SHON : Surface Hors Oeuvre Nette

This is obtained by deducting from the gross habitable space a certain number of floor areas corresponding :
  to attic and basement areas with ceilings below 1.80m
  to inaccessible terraces forming the roof
  to loft spaces that are non-convertible due to their impossibility to support loads or the bulkiness of beam work
  to basement areas assigned to the cellar (if there are no openings letting in natural light) and to technical rooms
  to balconies, loggias and open ground-floor areas
  to areas of the building designated for parking cars
  to rooms on agricultural premises for harvests, shelter for animals, agricultural material, transformation and packaging of products from the farm, production and storage of products for agricultural use.

From the area obtained after these deductions, and only for buildings for residential use, 5 % is deducted for thermal and acoustic insulation. Also, in the framework of building repairs, 5m² per accommodation unit can be deducted for the improvement of hygiene, closure of balconies, loggias and open areas on the ground floor.