The lack of knowledge of the structural behaviour and performances of timber structures often led to their loss and substitution with modern structures, or to invasive strengthening works. Ignorance is a cause of the loss of these structures also because the absence of recognition of their value does not give rise the need for their conservation. Just because ignorance is one of the main causes of loss of this heritage, knowledge is the first goal to be reached aiming to its preservation. The most important source of knowledge of an existing structure is its direct survey. The in situ investigations should aim to collect data about many aspects of the structure: general geometry and details of single members, internal joints, and metal reinforcements; wooden species and defects; evidences of decay; deformations or displacements; but also relation with other structural elements or systems, signs of timber processing, indications of the reuse of materials, etc. All the gathered data should allow an interpretation of the gradual change in time of the structure’s physical reality, of its technological conception and of its structural behaviour since the original design by the carpenter or engineer, trough the subsequent works or “natural” evolutions, unto the current state.

The stronghold of Arquata del Tronto was heavily damaged by earthquakes in 2016 and it drew the attention of the experts in reinforcing historic buildings. They regarded it as a case study, a predicting model of the failure in employing specific construction elements in fortified architecture, whose geometric and material data were only approximately considered. The overhanging battlement is the most seriously damaged part of the building and has raised particular attention and interest. As often happens in other castles and fortresses, it dates back to the late 19th and even more to the 20th century. A first close examination of the building’s repairs shows how the new additions, whose maintenance is difficult, ended in failure. The additions were inspired by ancient details, but nonetheless they are unreasonable from the point of view of structure and durability: they – and even more the irrational repairs of the last decades – are the principal cause of failure. Material decay – closely linked to circumstances and places – has also played a decisive role. An extensive and rigorous historical research is necessary to find the sources and to evaluate their nature and limits, as well as to relate all information to the building, thus operating in close correlation with the building archaeology, by now a so widespread and consolidated research field. Jointly, the written documents and the building itself in its historical stratification allow a better analysis of the structural behaviour , an essential step to achieve an effective restoration planning.

La Rocca di Arquata del Tronto è una fabbrica pluristratificata, la cui esistenza sarebbe attestata dal xiii secolo. Cessata da tempo la sua funzione militare e ormai ridotta a rudere, a partire dall'inizio del xx secolo, è stata oggetto di restauri volti a ridefinirne l'immagine, trasformandola in simbolo identitario della comunità arquatana. Gli eventi sismici del 2016 hanno messo in evidenza le vulnerabilità indotte da scelte non sufficientemente consapevoli dei temi della durabilità e del comportamento sismico, e da restauri sospesi e mai completati. L'articolo, dopo una ricostruzione storica degli interventi novecenteschi, evidenzia i fattori di vulnerabilità che hanno indotto i numerosi danni e identifica alcuni aspetti su cui dovrà prioritariamente concentrarsi il progetto di restauro.

Italian architecture was characterized by lower sloped roofs, and presented peculiar constructive solutions. In buildings without internal walls two principal solutions were employed: the most diffused was the so-called Lombard roof, the other was the Piedmontese roof.

In Italy, studies on wooden structural elements in masonry buildings, from the Middle Ages throughout the Modern Age to the twentieth century, are few in number compared to other European countries and present no systematic approach. It is necessary to carry out progressively, but systematically, high-detailed surveys and to correlate them with the existing discontinuous documentation. Diachronic comparisons – referring to significant geographical areas in which evident constructive constants are recognizable – would highlight the variation over time of the models and their diffusion, while the comparison, especially synchronic, between solutions evidently different or apparently similar, would allow to better understand both the constructive choices and their static behaviour. A series of models – including the structural ones – should be elaborated, for directing design in a sector, often seriously flawed, prone to simplification and the introduction of high safety factors essentially motivated by summary and inadequate surveys of the actual situation. It is also interesting to evaluate the application of mensiochronological techniques to the analysis of timber structures, especially floors. The significant measures for dating are various: dimensions and centre distances of beams and joists, width and thickness of the boards, dimension of the accessory elements (e.g. joint laths), but the working processes and tree species have a decisive impact on the measures of the artefacts. Mensiochronological techniques usually detect slow but evident variations; however, a centuries-old constancy is equally significant. More general information about the context is useful, in particular which choices are not determined by mere technical reasons. A better historical knowledge serves to understand the qualities and limitations of existing structures, and the features – including decay – in which they appear. The floors of Palazzo Magio in Cremona, dating from the fifteenth century to the end of the eighteenth century, allow to reflect on how and what to examine.