Zurich clears 4,000 flats from the ISOS backlog
In Zurich, a major obstacle to housing construction is being removed. On 18 September 2026, the Federal Council amended the rules governing the application of the ISOS and brought them into force on 1 November 2026. This means that projects that had been held up now stand a better chance of being approved.
The measures introduced by Bern affect two ordinances at the same time. On 18 September 2026, the Federal Council amended the VISOS and the Spatial Planning Ordinance in order to clarify the application of the ISOS and to simplify and speed up planning and authorisation procedures. For Zurich, this touches on a particularly sensitive issue, as around 75 per cent of its built-up area is subject to ISOS conservation objectives.
It was precisely this direct application that had brought housing construction to a standstill. As soon as a building project involved a federal responsibility in addition to the municipal procedure, the ISOS assessment took immediate effect. According to SRF, this had blocked projects for around 4,000 flats in the city of Zurich.
Greater flexibility in the planning permission process
The new regulations are intended to strike a better balance between the protection of the townscape and infill development. The federal government aims to define the scope for action of cantons and municipalities more clearly, make conservation objectives easier to understand and thus make the procedures more predictable. For property developers, co-operatives and property owners, this will above all increase planning and legal certainty.
The City of Zurich had already publicly highlighted the need for action on this issue prior to the amendment to the ordinance. From September 2025, it will once again be able to carry out the initial assessment itself in cases of direct application of ISOS, which will enable advice and the building permit process to be handled from a single source. The Federal Council’s revision is now proceeding further, as it is readjusting the legal framework itself.
Decision with effect from November
The amendments will come into force on 1 November 2026. It remains to be seen whether the blocked projects will be approved immediately thereafter, as each project must still meet the relevant protection and authorisation requirements. What is clear, however, is that the Federal Council has deliberately relaxed the previous practice so that housing construction and infill development in cities such as Zurich are less likely to be thwarted by townscape conservation requirements.