Illusion No. 21: Only lawyers know their way around building law!

Buying, evaluating or building real estate requires an intensive examination of building law. The following documents, laws and regulations are at the forefront of this:

• Local building and zoning regulations with zoning plan
• Cantonal Spatial Planning Act and implementing provisions.
• Court rulings and decrees

In the following, we would like to take a closer look at the most important technical terms and explain them. Both the definitions and the illustrations are taken from relevant legal texts, namely the PBG (Law on Spatial Planning and Public Building Law) of the Canton of Zurich. For the sake of simplicity, we will not cite the exact source (respective articles of the PBG) below.

1. the utilization rate

All rooms that are used for living, working or other permanent residence are relevant for the utilization factor. Only the areas on the full storeys are included in the utilization rate, but with the associated access areas and sanitary rooms and with internal partition walls. Areas in attics and basements only consume floor space if they exceed the area per storey that would result from an even distribution of the total permitted floor space over the permitted number of full storeys. Attic and basement storeys that replace a full storey, as well as basement storeys that are mostly above ground level, are considered full storeys for the calculation of the utilization factor.

The following municipalities around Lake Zurich have a utilization rate: Erlenbach, Hombrechtikon / Feldbach, Thalwil, Oberrieden, Wädenswil, Richterswil, Wollerau (SZ), Freienbach (SZ), Bäch (SZ), Altendorf (SZ), Rapperswil-Jona (SG).

2. building mass

The building mass index indicates how many cubic meters of enclosed volume are permitted per square meter of plot area. Only the above-ground enclosed space (visible cubature) with its external dimensions is to be measured for the calculation of the building mass index. There is a simple formula that can be used to calculate the building mass:

3. grown terrain

Which terrain is currently decisive for determining the maximum building height? When is the terrain considered to be heaped up and when is it considered to have grown? In recent years, this “grown terrain” has caused disputes in many cases, particularly when calculating the permissible building mass and building height. The issue has now been clarified for the canton of Zurich by a court ruling:

• Terrain conditions for conversions must be traced back to the date of the building application at the time.
• New buildings may be based on the current terrain if no changes have been made in the last 30 years.

This regulation is not a law, but corresponds to a court decision that could be reinterpreted by the courts at any time.

4. building height

The permitted building height is determined by the permitted number of full storeys or by the building and zoning regulations. Unless otherwise stipulated in the building and zoning regulations, the PBG stipulates that the building height is to be calculated on the basis of the permitted number of full storeys with a gross storey height of 3.3 m, or 4 m in central and industrial zones, and an additional 1.5 m for the elevation of the first floor. The permissible building height is measured from the respective intersection line between the façade and roof surface to the natural ground below. The ridge height is the permissible height for the top floor, which is normally permitted in addition to the building height.

5. building density

The area that can be taken into account for the superstructure ratio is determined by the vertical projection of the largest above-ground building perimeter onto the ground. Above-ground, enclosed projections up to a depth of 1.5 m, above-ground projections such as balconies up to a depth of 2 m, bay windows and arcades are not taken into account, but only if they do not measure more than one third of the façade in question. In addition to the superstructure ratio, the local building authority can also specify an open space ratio. This restriction is usually applied instead of a maximum building ratio.

6. building lines

Building lines secure the land for buildings and facilities in the public interest, such as roads, paths, squares, supply lines, etc. For the authorities, they are an important land-use planning instrument for traffic and development planning. The land between the building lines is generally subject to a building ban for this purpose. In practice, the land within building lines can be used for above-ground building projections up to a maximum of 1.5 m, e.g. for retaining walls, container sites, car parking spaces, etc. As soon as you apply for a permit for a building within the building lines, the state will register a public-law restriction on ownership (known as a “reversal”) in the land register. This means that it can issue the building permit (for a retaining wall, for example), but it will be noted in the permit and in the land register that if the land in the building line area is used by the state (e.g. for the construction of a sidewalk), the buildings must be removed again without compensation and at the expense of the builder.

7. forest and water distance lines

Building zones in the vicinity of forests or bodies of water are marked with a forest or water distance line. Normally, forest spacing lines are set at a distance of 30 m from the forest boundary. In the case of small forest plots or special local conditions, they can be drawn closer to or further from the forest boundary. When calculating the relevant land area for utilization or building mass, it should be noted that areas more than 15 m from the forest line can no longer be taken into account. In the case of a 40 m deep strip of land that borders a forest for 50 m (2,000 m2), the first 15 m do not count as the relevant land area. In other words, only 25m x 50m can be calculated as the relevant land area (1,250 m2).

Useful links

•  PBG (Canton of Zurich)
•  Geographical Information System of the Canton of Zurich
•  Building in the forest clearance area information sheet

PDF Ilusion No. 21

Author: Claude Ginesta

Claude A. Ginesta is a Swiss certified real estate trustee and CEO / owner of Ginesta Immobilien AG. The company was founded in 1944 and specializes in the sale of real estate in the economic area of Zurich and Graubünden. With branches in Küsnacht, Horgen and Chur, the company acts as an estate agent throughout Switzerland for properties with a supra-regional character.

Publisher of the Illusions series: Ginesta Immobilien AG, www.ginesta.ch