Construction outside the building zone - protection of acquired rights and necessity related to residential use meeting standard requirements (Art. 24c para. 4 SPA)

Federal Supreme Court, 23.10.2025, 1C_590/2024

Facts

The owners of a residential house located in an agricultural zone in the municipality of Schiers wish to build a garage of approximately 50 m² attached to their home. This project aims to replace an existing 21 m² garage, located on a neighboring plot 40 meters away, which must be demolished. The demolition is necessary because, following the widening of the cantonal road, the existing garage no longer meets road safety standards (distances and visibility).

A neighbor opposed the project. After the cantonal authority and the Administrative Court of the Canton of Grisons approved the building permit, the neighbor appealed to the Federal Supreme Court, challenging the project's compliance with Art. 24c of the Spatial Planning Act (SPA).

Legal Analysis

The case concerns the interpretation ofArt. 24c SPA, which governs buildings and installations legally erected outside the building zone before July 1, 1972 (so-called "grandfathered" structures). According to Article 24c, paragraphs 1 and 2: 

1 Outside the building zone, buildings and installations that can be used for their intended purpose but are no longer in conformity with the zone's designation are, in principle, protected by the guarantee of acquired rights.

2 The competent authority may authorize the renovation of such buildings and installations, their partial alteration, their measured expansion, or their reconstruction, provided that the buildings were erected or altered legally.

The residential building and the existing garage are lawful structures built before July 1, 1972, and benefit from the guarantee of acquired rights; they fall under the regime of Art. 24c SPA (consid. 2.1). 

Although technically classified as the demolition and reconstruction of a garage, the project must legally be assessed as a measured extension of the existing dwelling (Art. 24c para. 2 SPA). The requirement to maintain the building's identity (Art. 42 para. 3 OSPA) is met.

Art. 24c para. 4 SPA imposes an additional condition: changes to the exterior appearance must be necessary for residential use meeting current standards, for energy-related improvements, or to achieve better integration into the landscape. The Federal Supreme Court reiterates that the term "necessary" (nötig) within the meaning of Art. 24c para. 4 SPA must be interpreted restrictively, but that it is less strict than the term "indispensable" (unumgänglich) used in the context ofArt. 24d SPA. Necessity is assessed objectively and aims to allow for a contemporary standard of living, without authorizing solutions based purely on comfort or luxury. (consid. 2.)

In this case, the Federal Supreme Court first classifies the project not as a reconstruction of the small existing garage (which would make the expansion disproportionate), but as a measured extension of the main residential house, which is also a grandfathered structure. This approach is deemed more appropriate, as it would be illogical to penalize a project that includes the demolition of an existing structure. (consid. 2.2).

The Court then examines whether the extension is "necessary" for residential use that meets current requirements. It answers in the affirmative based on a set of specific circumstances (consid. 2.5.3):

1. The existing garage must be demolished for compelling reasons of road safety, beyond the owners' control.
2. Creating parking spaces in the existing barn or shed is not feasible, as the access is too steep and cannot be corrected without causing excessive damage to the landscape.
3. The project improves the land-use planning situation. It respects the principle of densification by attaching the garage to the house, freeing up an isolated plot, and contributing to a "decluttering" of the landscape.
4. The land area returned to agriculture (154 m²) is greater than the area newly used for construction (94 m²).
5. The house's location at an altitude of 950 meters, with potentially difficult winter conditions, objectively justifies the need for a covered garage attached to the home.
6. The size of the double garage is considered proportionate given the dimensions of the residential house.

The Court concludes that, in this specific case, the conditions of Art. 24c paragraphs 4 and 5 of the Spatial Planning Act (SPA) are met. (consid. 2.5.3, 2.6, 2.7). 

Consequently, the Federal Supreme Court rejects the appeal and upholds the decision of the Grisons Administrative Court. The building permit for the new garage, conditional upon the demolition of the old one, is definitively granted.

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