Istanbul's Crumbling Building Records Face a Reckoning: The Key Decisions Ahead

Istanbul's municipal mapping system holds tens of thousands of duplicate and outdated aerial images — some dating to surveys conducted before the 2023 Kahramanmaraş earthquakes fundamentally changed how Turkey thinks about structural risk. Now, with a court-mandated urban renewal audit underway and a national deadline approaching, city officials and independent cadastral firms are being forced to decide which images get replaced first, who pays for the work, and whether the resulting data will be publicly accessible.

The stakes are not abstract. In districts like Küçükçekmece and Bağcılar — both flagged by Istanbul Metropolitan Municipality's earthquake risk maps as high-priority zones — building stock has changed faster than the official image register can track. Illegal extensions, post-earthquake reinforcement work, and demolition all leave gaps or, worse, duplicated entries that show a building as it was rather than as it stands today.

Why the Timing Is Forcing a Decision

Turkey's Disaster and Emergency Management Authority, known as AFAD, set a rolling compliance schedule for municipal cadastral updates in zones classified as seismic risk category one or two. Istanbul has dozens of such zones. The Ministry of Environment, Urbanisation and Climate Change has linked a portion of urban transformation funding — disbursed under Law No. 6306, the legislation that governs the demolition and rebuilding of risky structures — to municipalities maintaining accurate, non-duplicated building records. Municipalities that cannot verify their image registers risk losing access to that funding stream.

For Istanbul Metropolitan Municipality, which has been managed by CHP mayor Ekrem İmamoğlu's administration since 2019, the practical problem is a contested one. The municipality's own geographic information systems directorate has been running a digitisation programme since 2021, focused on Fatih, Zeytinburnu, and Avcılar. But the cadastral imagery layer — maintained partly by the national General Directorate of Land Registry and Cadastre, known by its Turkish acronym TKGM — overlaps with municipal GIS data in ways that produce redundant records. When a building appears under two different parcel identifiers with conflicting imagery timestamps, planners cannot determine which record governs insurance assessments, demolition orders, or rebuilding permits.

The Fatih district alone, according to data published by Istanbul Metropolitan Municipality's urban planning department in a 2025 report, contains more than 18,000 building parcels where the cadastral image and the GIS layer do not match. Zeytinburnu adds several thousand more. These are not peripheral neighbourhoods: Fatih sits on the historic peninsula, dense with Ottoman-era structures that were never designed to meet modern seismic codes.

Three Decisions That Will Shape the Outcome

The first and most immediate question is sequencing. The municipality's planning directorate must formally submit a priority list to TKGM by September 2026, identifying which neighbourhoods get new orthophoto surveys first. Advocacy groups including the Chamber of City Planners Istanbul branch, whose offices are on Hobyar Mahallesi near Sirkeci, have pushed publicly for Küçükçekmece and Sultangazi to lead the list, given population density and building age. Whether the final list reflects seismic risk data or political considerations about where urban transformation projects are already underway is the central tension.

The second decision concerns data access. Under the current framework, updated cadastral imagery is classified and made available only to licensed professionals and public agencies. A coalition of civil society organisations, including the Istanbul Urban Transformation Monitoring Platform, has called for a publicly searchable interface — similar to what Ankara piloted in 2024 — so that residents can verify whether their own building's record is accurate before submitting renewal applications.

The third question is funding. New orthophoto survey work across Istanbul's 39 districts is estimated to cost between 180 million and 220 million Turkish lira under current contractor pricing, according to figures circulated in a Chamber of Surveyors bulletin from May 2026. Whether the central government, the municipality, or a cost-sharing arrangement covers that amount remains formally unresolved.

The September deadline for the priority list is the near-term marker to watch. If the municipality and TKGM cannot agree on sequencing before then, the urban transformation funding linked to Law No. 6306 could be delayed — which would slow demolition and rebuilding in the very districts where outdated imagery is the most dangerous problem.