Maintenance systems for wooden façades

From a long time architectural design is tackling the problem of the aging and deterioration of construction materials in the last phase of a building life cycle, a key concept from the point of view of environmental sustainability, because it allows the dismantling of buildings by disassembling their components without any further energy use. The aim of design is to find solutions, both at procedural and designing level, to improve the durability of both the single components and the whole building, expecting to intervene with preventive maintenance cycles or replacement of components without damaging the rest of the building (Gaspar & Brito, 2003). Buildings are composed of different layers who reach the end of life service in different phases of the life cycle. Several authors (Gaspar and Brito 2003; Hovde and Moser 2004)subdivide a building in different durability layers, i.e. in different functional layers(skin, structure, service, space plan, stuff), that reach the degradation state at different times from their installation. In Italy the diffusion of wooden buildings places greater emphasis on the durability of both the materials and the buildings built with them. In particular, envelopes are the most studied elements, because they are the elements more subjected to environmental agents, like meteorological events or UV rays, which are the main causes of wooden deterioration (Davoli 2001; Rüther and Time 2015). In order to provide durability to the technological element, it is important to guarantee both the natural component durability and the possibility of skin management. In fact, the former is important to guarantee the durability of the single skin components and their composition, the latter is important for the possibility to forecast inspection's cycles, maintenance's preventive cycle and/or substitution of element in case of damage (Hovde and Moser 2004; Manfron and Siviero 1998). The new Italian Public Procurement Code requires the designer has to guarantee not only the energy saving solutions during the phases of construction and use of the building, but it has to be also responsible for the assessment its of life cycle and maintenance solutions (art. 23 Dlgs n 56, 2017). The aim of this research is to identify through a set of case studies some best practices for improving the maintenance procedures of wooden envelope sand to improve the overall element durability. It will be investigated different case studies, with different functional models and different finishing solutions, to compile a list of designing suggestions for wooden façades. The façade will be investigated with some key requirements, which are described into the Italian standard UNI 8290, where there are the provisions related to the requirement of building components and language of Italian building system. The requirements that will be used in the analysis are: the accessibility, the inspection, the ability of the component to be installed/assembled, and the possibility to replace the components. The accessibility is the capability of examining the façade's layers after the building construction. This feature is linked to the functional model chosen for the considered technological element (e.g., ventilated facade, type with continuous insulating element and continuous finishing), and is crucial in the user's ability to judge the degree of wear and/or damage of one of the components. The inspection is the requirement that considers the possibility of changing or inspecting one or more façade's component, without damage for the rest of the element. This feature depends on the possibility of mounting and dismantling components. The ability of the parts to be installed/assembled, is the possibility of eventual disassemble of the skin's components without damaging the other elements, and with the possibility of reusing them after a temporary dismantling. This ability is related to the characteristics of fixings of the external finishing. The repairability and the ability to be replaceable, are the requirements whose consider the possibility of assessing how the single parts can be disassembled without damaging the entire technologic element, but only the local area of damage. In conclusion, the design of both elements and procedures to facilitate the maintenance and the possibility of changing parts of an envelope could increase the durability of wooden component façades. The aim of this research is to investigate a set of case studies to see which are the best practices to implement these capabilities and to indicate design suggestions useful to the designer approaching the design of wooden buildings.