How to calculate the sales surface?

Surface de vente

When reading an advertisement for the sale of a property, how can you be sure that the surface area displayed on the paper corresponds to the space actually available? The Swiss Union of Real Estate Professionals (USPI) has issued a set of standards applicable throughout Switzerland, with some cantonal nuances. Cardis Sotheby's International Realty clarifies it.There are several ways to measure the surface area of a dwelling. This can include, at most, the surface of the rooms, the surface occupied by the interior and exterior walls as well as that of the external parts (balcony, terrace). This is the gross sales area. The part of this surface actually available to the occupant, i.e. without the interior and exterior walls and external parts, is called the net living area. It is of course smaller than the gross sales area. To this can be added the area occupied by a cellar, a warehouse, an indoor parking space or a garden. This area is called the secondary, undeveloped usable area.

Calculation example

Let's take a house with a gross surface area of 100 m2. It has several rooms separated by interior walls and a balcony. Its surface area can be broken down as follows:

  • 75 m2 are actually available for the occupant. This is the net living area.
  • In addition, the interior walls and ducts (ventilation, electricity, etc.) cover 10 m2. This corresponds to the living area (85 m2).
  • In addition, there are the exterior and party walls, covering 8 m2. This is the gross living area (93 m2).
  • In addition, there is the balcony, covering 7 m2. All these elements build the gross sales area (100 m2).

These details are important because the price of housing is usually counted per square meter. And a selling price of CHF 7,000 per square meter does not give the same result if one counts the gross sales area (i.e. a price of CHF 700,000 for an apartment with a gross sales area of 100 m2 ) or the net living area (CHF 525,000 for the same apartment with a net living area of 75 m2 )! The cantons have established rules to harmonize this question :

  • In the cantons of Vaud, Fribourg and Neuchâtel, the determining surface is the net sales area, which covers the net living area plus the interior walls and exterior surfaces, but without the exterior walls.
  • In Valais, on the other hand, it is the gross sales area, i.e. that which also includes the external walls, which is the reference.

Be attentive therefore, two houses of identical surface area sold one in the canton of Vaud and the other in Valais do not offer the same net living space! The latter is larger in the canton of Vaud than in Valais. In the establishment of the sales area, certain housing elements are not counted at their full value, due to their characteristics. A balcony, a loggia and the interior walls therefore count for half of the gross sales area. A terrace accounts for a third. Mezzanines and attics are only counted as sales area if the distance from floor to ceiling is at least 1.50m. On the other hand, the gross sales area includes kitchen blocks, built-in cupboards, fireplaces and interior stairs.

Our Cardis Sotheby's International Realty agents are available to inform you about your sales area.