Abstrak Keruntuhan atap kayu pada bangunan publik merupakan peristiwa kritis yang menimbulkan risiko keselamatan dan menuntut evaluasi teknis yang akuntabel. Penelitian ini bertujuan menyajikan analisis forensik kegagalan atap kayu pada Balai Adat Dayak “X” di Kalimantan Utara yang terjadi segera setelah pemasangan penutup atap dan pelepasan penyangga sementara. Perubahan penutup atap dari seng (3,26 kg/m2) menjadi sirap kayu ulin (25 kg/m2) meningkatkan beban mati penutup atap sekitar 21,74 kg/m2 (0,213 kN/m2) atau 667% (7,7 x) dibanding kondisi awal, sehingga menaikkan tuntutan layanan elemen atap. Metode penelitian meliputi investigasi lapangan, pengujian laboratorium sifat material kayu, analisis manual gording sebagai elemen balok, serta pemodelan global rangka kuda-kuda menggunakan SAP2000 mengacu SNI 7973:2013. Evaluasi juga mempertimbangkan peran sambungan, pengaku lateral, dan perubahan kondisi pelaksanaan saat penyangga sementara dilepas. Hasil menunjukkan gording eksisting melampaui kriteria kekuatan lentur dan batas lendutan, sedangkan elemen kuda-kuda secara global masih aman terhadap gaya aksial. Temuan ini menegaskan bahwa kegagalan lokal elemen sekunder dapat memicu keruntuhan sistem atap secara keseluruhan. Studi ini memberikan dasar teknis bagi pengendalian perubahan spesifikasi material, pemeriksaan lendutan, dan pengaturan tahapan pelepasan penyangga pada konstruksi atap kayu. Kata kunci: Atap, Forensik, Gording, Kayu, Keruntuhan Abstract Public timber-roof collapses are critical events that pose safety risks and require accountable technical evaluation. This study aims to present a forensic analysis of a timber roof failure at the Dayak Traditional Hall “X” in North Kalimantan, which occurred shortly after roof covering installation and the removal of temporary supports. Replacing a metal sheet roof (3.26 kg/m2) with ironwood shingles (ulin) (25 kg/m2) increased the roof dead load by about 21.74 kg/m2 (0.213 kN/m2), equivalent to 667% (7.7 x) relative to the original condition, thereby increasing serviceability demands on roof components. The methodology includes field investigation, laboratory testing of timber material properties, manual analysis of purlins as local elements, and global modelling of the roof truss using SAP2000 in accordance with SNI 7973:2013. The evaluation also considers the role of connections, lateral bracing, and construction-stage changes when temporary supports were removed. Results indicate that the existing purlins exceeded bending strength and deflection limits, while the truss members remained globally safe in terms of axial forces. These findings confirm that local failure of secondary elements can trigger collapse of the specification changes, checking deflections, and managing the timing of temporary support removal in timber roof construction. Keywords: Roof, Forensic, Purlin, Timber, Collapse