Background: The knowledge of the structure of an artefact, as well as that of its constituent materials and of the hosting environment surely ensures safe guideline for its restoration. Unfortunately, in most cases, a scientific investigation preliminary to restoration is not accomplished due to its high costs and, as a fact, diagnostics is performed only for very precious artworks. This paper aims to provide a multidisciplinary diagnostic procedure that, although not exhaustive, is rigorous and relatively low cost. It was employed in view of the restoration works on a country church located in Sardinia. A careful inspection of all the architectural elements was carried out in order to highlight structural damages as well as sources of them. One stone and one plaster samples were analysed. The salt content was determined, in two different areas of the church, using three different sampling procedures while only the normed method was used for the determination along the stratigraphy of the sampled plaster. Microclimate monitoring was also carried out.Results: Water infiltration through the roof was observed. Natural stones and artificial building materials used in the basic architecture resulted to have local source. Both the preliminary "by eye" inspection and the optical microscopy revealed several finishing layers in the investigated plaster samples. The salt content, with some exception, resulted rather low. Microclimate parameters show significant variations only in few areas of the building. Conclusions: Damage observed inside the oldest part of the Church seems to be mainly related to water infiltrations through the roof and the lack of an effective drainage of the rainwater due to a previous bad restoration. Masonry from one of the newest rooms, showing a strong biodeterioration, as well as some areas inside the nave, revealed a significantly high sulphate content. Building materials (stone and aggregates of mortars) are of local provenance.

Due to the bad state of conservation, "Palazzo Governi", a seventeenth-century building located in the old town district of "Stampace" in Cagliari (Sardinia, Italy), was subjected to restoration. Thus, according to the Italian Law n. 1089, the main façade colour must be reproduced, and therefore, its identification was required. The available samples looked fairly degraded, in particular as an easy plaster to crumble; so, some other analyses able to identify the degradation cause were performed. Two different approaches were adopted to attain the first goal, the visual colour assessment by a sensory panel (subjective) and the instrumental measurement by colorimetry (objective). Ion chromatography and inductively coupled plasma-optical emission spectroscopy analyses, as well as conductivity and pH measurements, were performed to evaluate the presence of water-soluble salts inside the plaster, as possible cause of degradation; the binder/aggregate ratio was also evaluated. A full mineralogical and petrographic characterisation of the materials constituting the samples, as well as the identification of their stratigraphy and some other morphologic and structural features suitable to highlight eventual forms of degradation, were performed by optical microscopy. Scanning electron microscopy coupled to X-ray microanalysis was been also used in order to confirm and/or to integrate data obtained by optical microscopy. The samples have been compared with two samples coming from two other buildings, also located in Sardinia, that looked in good conservation state. The results evidenced that the causes of degradation come from a high salt (especially sulphate) content and a scarce presence of binder in the plaster that can be imputed to a wrong initial composition and/ or to a leaching by acidic rain.