Toward integrated assessment of timber heritage structures: a systematic review of settings, scopes, and schemes

Timber heritage structures require systematic assessment that integrates multiple methods. This systematic review examines peer-reviewed studies on field-applied assessment of timber heritage structures, excluding laboratory-only tests. Based on 91 papers from the Web of Science database, this study establishes a Setting–Scope–Scheme framework to clarify relationships among assessment targets, conditions, purposes, methods, and indicators. In addition, 124 extended abstracts from the Architectural Institute of Japan literature database are reviewed as supplementary materials for region-specific comparative analysis. The results show that assessment practices are shaped by regional contexts, structural typologies, and environmental conditions. Assessment indicators also show hierarchical and networked characteristics across system, component, and joint levels, involving functional, conditional, and environmental-interaction coupling. Technological integration, including long-term monitoring, numerical simulation, and BIM, supports multi-indicator assessment and less invasive conservation practice. Although limited by database coverage and heterogeneity in indicator reporting, this review provides a structured basis for context-adaptive assessment strategies.