Vernacular architecture, with its multiple morphologies, variants, materials and constructive solutions, forms part of the cultural identity of a given country, region or place. It is the result of...

Traditional architecture is the result of collective experience in the optimum use of available materials in a given location and adapted to specific conditions and needs. Although forms and groups also depend on other cultural and social issues, the constructive techniques used depend mostly on geographical conditioning factors such as altitude, hydrography, lithology, climate, etc. This text aims to analyse the possible relationships among the multiple variants and specific geographical conditioning factors of each location; in turn, this should provide an understanding of the reasons motivating or reducing their use and the mechanisms adapting these techniques to these conditioning factors. The analysis cross-referenced GIS systems from a database compiling information on 1160 half-timbered walls with a series of themed maps containing information on geographical factors. The conclusions reached show that a single technique adapts to different geographical conditioning factors, giving rise to a wide range of solutions which can provide greater durability and improved habitability. This capacity to adapt to the location is a lesson in sustainability that can be applied at present and is above all part of the intrinsic wealth and value of traditional architecture.

This analysis of the material degradation processes most commonly found in half-timbered walls with earth infill in Spain is part of a much broader line of research aiming to analyze, catalogue and understand their constructive techniques, state of conservation, and transformation in order to propose conservation guidelines. Systematic data collection and statistical analysis of material damage for 268 half-timbered walls with earth infill have made it possible to identify the most common degradation processes. The effect of these processes on this type of technique, as well as the relationship between them and any possible conditions contributing to their frequency, were examined. Almost half of the sample studied presents some type of material degradation, most frequently surface erosion, while the presence of vegetation is the least common pathology. Any future decisions about the most suitable maintenance and conservation actions should be based on the conclusions reached here concerning the frequency and scope of these degradation phenomena.

The term "half-timbered walls with earth infill" refers to a wide number of techniques in which structural wooden elements are combined with enclosures made of earth. The use of these constructive systems dates back to prehistoric times and their evolution has differed based on the physical, social and cultural conditions of each place. Therefore, the objective of this paper is to define the concept of half-timbered walls with earth infill in the Spanish context and to understand the geographical, urban, architectural and constructive reasons that have favoured or hindered its use in traditional architecture. The methodology used is based on the quantitative and qualitative analysis of the largest possible number of case studies. This allows a database to be set up for the purposes of performing global analysis and drawing objective and statistically valid conclusions. This information is managed using a study sheet with information ranging from general aspects of buildings with the presence of these techniques to detailed features of half-timbered walls. The data and conclusions presented in this paper focus on these half-timbered walls, including information on the geographical distribution of these techniques, the characteristics of the buildings in which they are used, the combination of mixed walls with other construction techniques, and the state of conservation and transformation of the buildings in which they are used. It has been established that these techniques are common in mountainous landscapes, where there is optimal woodland for construction, and in urban environments, where they are presented as optimum techniques to maximize the profitability of the buildable surface.

Traditional architecture characteristically uses locally available materials to develop constructive systems and techniques, providing an optimum response to the needs of the population. This study focuses on half-timber walls as a traditional technique taking material form in a wide range of variants found mostly in the northwest half of Spain. Primarily aiming to ensure the broad objective of in-depth documentation, understanding, and study, the microscopic analysis of 24 timber samples obtained from different half-timber walls is proposed. This analysis aims to identify the species or species groups used and to establish a correlation with different aspects of construction including structural resistance, durability, and workability. This makes it possible to identify the predominant use of species found close to the locations from which the samples are obtained, using relatively resistant species for the structural elements of the half-timber wall, as well as the use of species with flexible and easily malleable branches for the construction of the enclosure panels. This indicates that, among the species available in a given location, builders have a degree of knowledge on the characteristics of the material, so they could choose the most suitable ones or develop specific constructive solutions based on these characteristics.

The systematic data collection and quantitative analysis of 225 half-timbered walls found in the province of Burgos made it possible to reach conclusions on the frequency and scope of 27 phenomena of material degradation and 11 types of structural lesions. Almost the entirety of the sample analysed presents some degree of material degradation, mostly slight atmospheric lesions such as surface atmospheric erosion and chromatic alteration and dehydration of the timber. A greater vulnerability to structural lesions, particularly structural deformation, has been observed in this type of wall. The results presented in this text form the basis for understanding the conservation and restoration needs of half-timbered walls, given the indispensability of knowledge of the most common degradation systems.