Tabique buildings heritage in the Alto Douro Wine Region, Portugal

The Alto Douro Wine Region in northeast Portugal, inscribed as a UNESCO World Heritage landscape, preserves a rich legacy of vernacular construction shaped by local materials and traditional knowledge. Among these, Tabique buildings represent a distinctive Portuguese timber-framed technique incorporating earth-based infill, stone masonry, and metallic connectors. This paper presents an engineering-oriented synthesis of Tabique construction derived from fieldwork, laboratory characterisation, numerical modelling, and statistical surveys. The study systematises architectural typologies, material properties, structural behaviour, deterioration mechanisms, and conservation states, while proposing a practitioner-oriented workflow for structural assessment and compatible rehabilitation. Findings indicate that although many Tabique buildings exhibit deterioration, their constituent materials often retain satisfactory mechanical performance. Furthermore, numerical and experimental investigations demonstrate adequate vertical load-bearing capacity, acceptable fire resistance, and moderate thermal performance. Despite these favourable characteristics, prevalent rehabilitation practices involve the demolition of original timber systems and their replacement with reinforced concrete or steel, potentially compromising heritage value. The results highlight the need for specialised preservation approaches that reconcile structural safety and regulatory compliance with the protection of traditional systems. By providing a scientific basis for Tabique performance, this work contributes to the long-term preservation of the Alto Douro landscape through technically sound and sustainable interventions.