14 October 2026 — Ramzi Chamat
USPI weighted floor area: apartments and villas explained
USPI weighted floor area provides a transparent basis for comparing sales areas, but does not constitute a property valuation on its own. For an apartment held in condominium ownership, known as PPE in French-speaking Switzerland, indoor and weighted outdoor areas must be distinguished. For a detached house or villa, land, building volume, external works and ancillary costs are central considerations.
The essential distinction is between measurement recommendations, valuation assumptions and construction costs. This guide explains the verified rules, calculations and limitations for property in Geneva and French-speaking Switzerland.
What USPI actually recommends
The source reviewed is USPI Suisse’s French-language document “Recommandations concernant un mode standard de calcul des surfaces”, August 2014, version 1, available through USPI Vaud’s Documents section and consulted on 14 October 2026. Its upload date should not be confused with its edition date. [1, 2]
It recommends, among other things:
- Balconies and loggias: 50% of their area.
- Terraces: 33%, using the document’s definition of a terrace.
- Separate reporting of indoor living areas and external areas, with areas also shown by floor.
- Exceptions where objectively justified and accompanied by an explanation of the calculation method.
In USPI’s worked example, the exclusive-use garden, cellar, storage room and parking spaces are listed separately. The document does not assign them a universal coefficient for automatic inclusion in the sales area. Separate reporting does not mean they have no value. [1]
Clarification of the general benchmarks discussed in our earlier guides: a garden or cellar coefficient used in a valuation is not automatically an official USPI coefficient. Walls are not always excluded either: their treatment depends on whether the basis is net or gross. The explanations in this article take precedence when interpreting the USPI method.
Net or gross area: establish the correct basis
The French abbreviations used in the source help avoid comparisons between different types of square metre: [1]
USPI term | Principle |
|---|---|
SNH, net living area | Net measurement basis, subject to the document’s detailed rules |
SCI, internal construction area | Area occupied by internal construction elements |
SH, living area | SNH + SCI |
MEM, external and party walls | Additional wall area used for the gross basis under the relevant practices |
SBH, gross living area | SH + MEM |
SVN, net sales area | SH + weighted external areas |
SVB, gross sales area | SBH + weighted external areas |
For the MEM addition, USPI specifies 100% of external walls and 50% of party walls, according to the relevant cantonal practices. A marketing description such as “PPE area” therefore needs an accompanying definition: the label alone does not establish how the area was measured.
Apartment calculation: from weighted area to indicative price
Using a clearly identified SH basis, the following illustration applies the document’s coefficients:
Net sales area = SH + balcony × 0.50 + terrace × 0.33.
Component | Actual area | Weighting | Included area |
|---|---|---|---|
Living area SH | 100 m² | 100% | 100 m² |
Balcony | 20 m² | 50% | 10 m² |
Terrace | 30 m² | 33% | 9.90 m² |
Total SVN | 119.90 m² |
These are fictional teaching figures, not details of a marketed property. An 80 m² garden and a 10 m² cellar would be shown separately, without an automatic coefficient being added to this calculation.
One possible commercial calculation is indicative price = weighted area × CHF per weighted m² + parking price, provided parking is not already included. On purely hypothetical assumptions, 119.90 m² × CHF 12,000/m² + CHF 40,000 produces CHF 1,478,800.
The unit price must be derived from comparable properties measured on the same basis, with their ancillary amenities taken into account. This multiplication is a valuation approach, not a USPI price schedule. Adding parking, a garden or a cellar already reflected in the comparable pricing would double count their contribution.
Villas: land and building volume, without counting the building twice
For detached houses, USPI states that the sale price generally takes account of land, building volume, external improvements and ancillary costs. It does not prescribe an automatic sum of “land + building value per m² + value of the same building per m³”. [1]
Two approaches can inform each other, but their results should not be added together:
- A market comparison approach, considering similar villas, their floor area, plots, condition and location.
- A component-based approach, considering land and building value, external works, ancillary costs and necessary adjustments, including depreciation.
A wholly fictional component-based example:
Component | Assumption | Amount |
|---|---|---|
Land | 600 m² × CHF 1,200/m² | CHF 720,000 |
Building as new | 900 m³ × CHF 850/m³ | CHF 765,000 |
External improvements | Assumed amount | CHF 90,000 |
Ancillary costs | Assumed amount, excluding items already included | CHF 75,000 |
Subtotal | CHF 1,650,000 | |
Depreciation for this example | Hypothetical deduction | − CHF 120,000 |
Indication after depreciation | CHF 1,530,000 |
This is neither a guaranteed price nor a Geneva market benchmark. It must be checked against comparable transactions. A further value calculated by multiplying living area by a selling price must not be added: that could count the same building, and potentially the land, a second time.
Weighting ranges: study assumptions, not a USPI schedule
The ranges below are sensitivity assumptions to examine in a study, not coefficients validated by the USPI document consulted. They are not a recommendation for systematic use. Where areas are described as being calculated according to USPI, departures from the standard method must be justified and disclosed.
Area | Apartment assumption | Villa assumption |
|---|---|---|
Selected living-area basis | 100% | 100% |
Balcony / loggia | 30–50% | Assess separately |
Veranda | Assess separately | 50–80% |
Terrace | 30–50% | 20–40% |
Garden | 10–30% | 5–15% |
Garage / parking | Separate amount if not included | 40–60% |
Cellar | 5–10% | 20–40% |
Non-habitable attic storage | 20–40% | Assess separately |
Finished basement | 60–80% | 60–80% |
Unfinished basement | 20–40% | 20–40% |
Pool area | Assess separately | 10–30% |
A heated veranda, a non-habitable attic and habitable accommodation under a roof are not interchangeable. USPI distinguishes habitable roof space from non-habitable attic storage and gives a 150 cm height rule for mezzanines and habitable roof spaces, subject to cantonal provisions. A finished basement does not automatically become legally habitable accommodation. [1]
For a villa, the garden area should not automatically create additional land value where that land has already been counted. A pool also needs to be considered in terms of condition, equipment and market expectations: its water surface is not residential floor area.
Development feasibility: distinguish revenue from costs
In an apartment development feasibility appraisal, forecast sales revenue may be assessed using weighted sales areas and comparable unit prices, with separately priced parking added where appropriate. On the expenditure side, volume in m³ × construction cost in CHF/m³ can provide an initial construction budget, provided both the volume definition and the included works are consistent.
That budget is not the total development cost. Land, professional fees, taxes, financing, external works and contingencies must be examined without counting items already included in the cubic-metre rate twice. Sales-area coefficients do not automatically convert square metres into construction volume.
The shortcut “balcony 40%, garden 20%, cellar 5%” remains a modelling convention. The source reviewed does not establish that it is sufficient for 90% of feasibility appraisals. A useful analysis compares scenarios rather than attaching false precision to a single assumption.
Key takeaways
- The reviewed USPI reference specifies 50% for balconies/loggias and 33% for terraces.
- Gardens, cellars and parking are listed separately in the official example.
- Weighted areas are comparable only when their measurement definitions match.
- A villa requires analysis of both land and building; do not add two valuations of the same building.
- Modelling coefficients must remain clearly identified and justified assumptions.
For OAKS GROUP SA, sound analysis begins with transparent area schedules and traceable assumptions. Our Geneva property valuation tool offers an initial starting point, to be supplemented by examining the property and its documentation.
Frequently asked questions
Should a balcony be weighted at 40% or 50%?
The USPI document reviewed uses 50%. Another coefficient, including 40%, requires an explicit justification and should not be presented as the standard rule.
Can 20% of a garden automatically be added to an apartment’s sales area?
No. USPI’s example lists the exclusive-use garden separately. Valuing it through an area coefficient is a separate assumption that must be explained.
Is a villa worth its land value plus its square-metre and cubic-metre values?
Not where that adds two valuations of the same building. Market comparison and component-based calculations help cross-check a valuation, not accumulate multiple totals.
Can gross sales area include walls?
Yes. USPI’s SVB calculation includes the external and party-wall addition under the stated rules, unlike SVN. Identify the measurement basis before comparing prices per square metre.
Sources
- [1] USPI Suisse, Recommandations concernant un mode standard de calcul des surfaces, August 2014, version 1, particularly the detached-house and exceptional-case sections and the apartment calculation example. French original consulted on 14 October 2026.
- [2] USPI Vaud, Documents: standard method of calculating areas, public recommendations section, consulted on 14 October 2026.
The sensitivity tables and monetary examples are teaching illustrations, separate from the cited recommendations; they are not market prices.
