Swiss listings quote a floor area. Few buyers ever check it — and at Zürich prices, a five-percent error is a five-figure mistake.
At roughly CHF 13,000 per square metre in the city, every square metre in the listing is worth about as much as a small car. If the advertised area is generous by four or five square metres — sloping ceilings counted in full, a balcony counted as living space, a cellar room quietly included — you may be paying CHF 50,000 or more for space that does not exist in the way you think it does.
What counts, and what doesn’t
In Switzerland, floor areas are normally calculated to SIA 416, which distinguishes carefully between the gross floor area (Geschossfläche), the net floor area (Nettogeschossfläche) and the usable area (Nutzfläche). A listing that quotes one and implies another is not necessarily dishonest — but it is not comparable with the flat you saw yesterday either.
The recurring sources of difference, in our experience:
- Sloping ceilings. Under a roof, area below a certain height contributes partially or not at all — the single most common source of inflated figures in attic conversions.
- Balconies, loggias and terraces. Often included at a reduced rate, sometimes included in full, occasionally not at all. Three flats, three conventions.
- Cellars, storage and hobby rooms. Frequently counted as usable area when they are not habitable space.
- Interior walls and shafts. Gross versus net figures can differ by several square metres in the same apartment.
- Converted space without permission. A cellar or attic made habitable, counted as living area — but never approved.
Why it matters beyond the price
Floor area is not only what you pay for. It drives the comparison you make between properties, the rent you can expect if you let the flat, the value a bank will lend against, and — in Stockwerkeigentum — the Wertquote, the share that determines your vote and your contribution to every collective cost the building incurs. An error there compounds for as long as you own the property.
How we verify it
We measure the apartment independently with a laser measure, room by room, recording ceiling heights where they vary, and we reconcile our measurement against the plans and the listing. The report states what the area is, how it was calculated, and where any difference comes from — plain enough to hand to a seller or a bank.
It is a modest addition to a survey and occasionally the single most valuable page in it. We include area verification in every full building survey, and can carry it out as a standalone measurement where a purchase, a rent adjustment or a dispute turns on the number.