SIA 416:2003 – Surfaces and Volumes of Buildings Standard
The SIA 416:2003 is the registered Swiss standard (SN 504 416) issued by the Schweizerischer Ingenieur- und Architektenverein (SIA). It establishes a uniform framework for the definition and calculation of areas and volumes for both existing and planned buildings and their surrounding land. This edition, published in September 2003, replaces the previous SIA 416 (1993 edition) and the SIA 116 (1952 edition). It serves as a technical basis for area certificates, economic feasibility studies, variant comparisons, and statistical data collection in the Swiss construction and real-estate sectors.
The scope of the document encompasses land plot areas, building floor areas, and internal and external volumes. It explicitly defines a hierarchy of terms such as Grundstücksfläche (GSF), Geschossfläche (GF), and Gebäudevolumen (GV). The standard organizes these metrics into specific sub-categories, including net floor areas, construction areas, and functional volumes. Notably, the document clarifies that it does not define legal or zoning terms such as Ausnützungsziffer (exploitation index) or Bruttogeschossfläche (gross floor area as defined in building codes), which are governed by municipal or cantonal building laws.
The following sections detail the structured breakdown of land and building metrics according to the official SIA 416 terminology, including the specific categorization of surfaces for rental and condominium ownership purposes.
Land Area (Grundstücksfläche GSF)
The Grundstücksfläche (GSF) represents the total area of the considered plot and is subdivided into two primary components based on building intervention.
- Gebäudegrundfläche (GGF): The part of the land occupied by buildings or building parts projecting into the ground.
- Umgebungsfläche (UF): The remaining land area not occupied by buildings, further divided into Bearbeitete Umgebungsfläche (BUF) and Unbearbeitete Umgebungsfläche (UUF).
Floor Area (Geschossfläche GF)
The Geschossfläche (GF) includes the horizontal areas of all accessible floor levels, including the construction components. It is bifurcated into net areas and structural footprints.
- Nettogeschossfläche (NGF): The part of the GF located between the enclosing construction components.
- Konstruktionsfläche (KF): The area occupied by load-bearing and non-load-bearing structural elements, such as exterior and interior walls, columns, and niches.
- Nutzfläche (NF): A sub-category of the NGF used for the building's primary purpose, divided into Hauptnutzfläche (HNF) and Nebennutzfläche (NNF).
- Verkehrsfläche (VF): Areas dedicated to circulation, such as corridors, stairs, and elevator shafts outside of individual apartments.
- Funktionsfläche (FF): Space required for technical building systems and installations.
Building Volume (Gebäudevolumen GV)
Building volume is calculated based on the floor area (GF) and the corresponding heights. Foundations required for soil improvement are excluded from this calculation.
- Nettogebäudevolumen (NGV): The volume between the inner surfaces of the enclosing construction components.
- Konstruktionsvolumen (KV): The volume of all enclosing and internal structural parts, including walls, ceilings, and roofs.
- Aussen-Konstruktionsvolumen (AKV): The volume of external components such as balconies, canopies, and open galleries.
Rental and Condominium Areas
Section 4 provides a classification system for areas used in rental agreements or condominium ownership (Stockwerkeigentum), regardless of the ownership form.
- Flächen zur Sondernutzung (FSN): Areas for the exclusive use of a specific tenant or owner, including internal net areas and external net areas.
- Flächen zur gemeinsamen Nutzung (FGN): Areas shared by multiple tenants or owners, or those required for general building operation.
Frequently Asked Questions
Does SIA 416 define the gross floor area for building code compliance?
No. Section 0.1 explicitly states that SIA 416 does not define building law terms like Bruttogeschossfläche or Ausnützungsziffer. These are determined by local building regulations.
What is the difference between HNF and NNF?
HNF (Hauptnutzfläche) is the area serving the building's primary purpose, while NNF (Nebennutzfläche) includes auxiliary spaces such as laundry rooms, cellars, and storage areas.
Are balconies included in the floor area (GF)?
No. Areas outside the enclosing building envelope, such as balconies and terraces, are classified as Aussen-Geschossfläche (AGF) rather than Geschossfläche (GF).
What does the Konstruktionsfläche (KF) include?
The KF includes the cross-sections of all load-bearing and non-load-bearing walls, columns, and building supports, as well as wall niches and shafts.
How is the Gebäudevolumen (GV) calculated?
The GV is calculated by multiplying the Geschossfläche (GF) by the corresponding heights, representing the total volume within the building's envelope.
Are technical equipment rooms included in the net floor area?
Yes, technical spaces are classified as Funktionsfläche (FF), which is a sub-component of the Nettogeschossfläche (NGF).
