How Istanbul's Building Permit Archives Ended Up Full of Duplicate Images — and Why Fixing It Now Matters

Istanbul Municipality's building permit database contains an estimated 340,000 duplicate image files — scanned plans, site photographs and structural certificates uploaded multiple times across incompatible systems — according to figures presented to the Istanbul Metropolitan Municipality's (IBB) Urban Transformation Directorate in late 2025. The problem, years in the making, has slowed earthquake-risk assessments in some of the city's most vulnerable districts and drawn fresh urgency after the 2023 Kahramanmaraş earthquake exposed just how poorly many Istanbul buildings are actually documented.

The issue matters now because Turkey's Ministry of Environment, Urbanisation and Climate Change set a January 2026 deadline for all metropolitan municipalities to complete digital inventories of pre-1999 buildings — those constructed before the updated seismic code came into force. Istanbul missed that deadline for roughly 60 of its 39 districts' older neighbourhoods, and IBB officials have pointed internally to the duplicate-image problem as a core reason why automated risk-scoring tools kept returning errors.

How the Duplication Problem Was Built, Layer by Layer

The roots go back to 2008, when the 39 district municipalities that ring Istanbul each ran their own permit offices with their own scanning protocols. Fatih Municipality, which covers the historic peninsula, used one document management vendor. Kadıköy, on the Asian side, used another. When IBB launched its centralised e-permit portal, eBelge, in 2014, it ingested records from all 39 offices without a deduplication step. Files named with different date stamps but containing identical scans came in as separate records.

A 2019 IBB audit — never publicly released but cited in a 2025 administrative court filing in the Istanbul 4th Administrative Court — found that approximately 18 percent of all image files in the permit archive were exact or near-exact duplicates. The audit recommended a hash-based deduplication process, but the project was shelved after a budget dispute between IBB and the central government, which at the time was contesting the municipality's spending authority under Mayor Ekrem İmamoğlu following his contested 2019 election victory.

By 2023, three separate IBB departments — the Historic Peninsula Directorate, the Bosphorus Coastal Management Office and the Urban Transformation Directorate — had each begun their own partial clean-up projects without coordinating. The result was a third layer of records: corrected files sitting alongside both the original duplicates and the earlier uncorrected scans. Technicians working on the Eminönü-Haliç urban renewal zone, along the Golden Horn waterfront, reported spending up to 40 percent of project hours on manual image verification rather than substantive assessment work.

What the Court Ruling Changed — and What Comes Next

The turning point came in September 2025, when the Istanbul 4th Administrative Court ruled in favour of a Beyoğlu property owner who argued that conflicting scanned records in the IBB system had wrongly flagged his building as lacking a valid occupancy permit. The court ordered IBB to audit and correct its digital archive within 180 days — a deadline that lands in March 2026, already passed, leaving the municipality in an ongoing compliance obligation.

IBB responded by contracting Türkiye Bilimsel ve Teknolojik Araştırma Kurumu (TÜBİTAK), the national science and technology agency, to deploy an automated image-matching algorithm across the permit database. Work began at the Çağlayan courthouse records annex in February 2026, starting with Şişli and Beşiktaş districts, which together hold around 47,000 pre-1999 building files. The first phase cleared roughly 12,000 duplicate images in six weeks, according to the IBB Urban Transformation Directorate's published quarterly progress report for Q1 2026.

For residents in earthquake-risk zones — particularly those in Avcılar, Bağcılar and Zeytinburnu, all of which sit on soft alluvial soil and are flagged as high-risk in the city's own 2022 microzonation study — the practical consequence is direct. Buildings that could not be scored for the urban transformation subsidy program, which offers homeowners up to 500,000 Turkish lira toward demolition and rebuild costs, were stuck in a queue partly because their permit records could not be verified. Clearing duplicate images is, in that sense, not a technical housekeeping exercise. It is the administrative precondition for getting people out of dangerous structures before the next major earthquake arrives.