## 1 Introduction  
Natural stones and other commonly resistant construction materials can be damaged in cold climatic conditions. According to the Koppen classification [1], the subarctic climate (also identified as subpolar or boreal; abbreviated Dfc) is characterized by long winters and cold and short summers. This climate usually occurs on large intracontinental landmasses, often away from the mitigating effects of oceans, mainly between 50\({}^{\circ}\) and 70\({}^{\circ}\) N latitude. Subarctic climates are represented by the Koppen climate classification, and they are divided into six categories: Dfc, Dwc, Dsc, Dfd, Dwd, and Dsd [1]. Based on [PERSON]'s description, the first D letter indicates a continental climate where the temperature of the warmest month is \(\geq\)10 \({}^{\circ}\)C, and the temperature of the coldest month is \(\leq\)\(-3\) \({}^{\circ}\)C. The second letter indicates: s = dry summer, w = dry winter, and f = without dry season. The third letter denotes temperature: c = regular subarctic and d = severely cold subarctic. The Dfc climate is by far the most common subarctic type and is the one selected in this study (Figure 1). It has so far been found in the majority of Siberia, Fennoscandia, some portions of central Romania and Germany, Alaska, Labrador, Ontario, and the Canadian Prairies [2]. At middle latitudes, it can be found on the orogenic-like Alps and Pyrenees at elevations of 1600 < Z < 2100 m a.s.l. [3, 4]. Most of the subarctic climate sites show little precipitation that never exceeds 380 mm/year. Differently from hot-mild (Casa, Csb) or humid continental regions (Dfa, Dfb), in coastal areas with a subarctic climate and also in subarctic climate areas far from the coast, precipitation occurs mostly in the warmer summer months [3]. Subarctic climate regions are normally considered unwelcoming even if ancient and contemporary human settlements are present in these zones [5]. Examples of extreme temperatures in Dfc climate zones were registered in: Livigno, Italy (\(-37\)\({}^{\circ}\)C); Tatra Mountains, Poland (\(-40\)\({}^{\circ}\)C); Petropavlovsk-Kamchatskiy, Russia (\(-31.7\)\({}^{\circ}\)C); and Old Crow, Canada (\(-59.4\)\({}^{\circ}\)C). Such considerably low temperatures have a strong damaging effect on stone building materials. In this paper, the results of a laboratory simulation of a subarctic climate, carried out in a climatic chamber, are presented. Figure 1: (**a**) Worldwide distribution of subarctic climate according to [PERSON] [1]; (**b**) Livigno (Italy); (**c**) Turku (Finland); (**d**) Les Angles (France); (**e**) Samedan (Switzerland) during winter. Slate and Other Building Materials Performance at Low Temperatures  
Slate is quarried in several European countries (e.g., England, France, Italy, Spain, Belgium and Portugal) and is marketed all over the world. Together with quartzites, hornfels, and gabbros, it is one of the most durable stones in cold climate regions and used in mountain localities throughout Europe for roofing (Figure 2a), coverings, and wall ashars, thus representing a typical example of the use of local and traditional raw materials in vernacular architecture [6; 7]. Slates are formed by low- or very low-grade metamorphism that gives them slaty cleavage, where phyllosilicate minerals are the predominant components of the rock. Slates are relatively light and characterized by good fissility that allows them to split into tiles and, most importantly, to have good waterproofing properties [8; 9]. Some slates are particularly prone to deterioration (Figure 2b,c), especially in cases of sand intercalation, microfractures, and a high presence of carbonates. These compounds may affect the slate's physical, mechanical, and aesthetic quality in different ways: by reducing waterproofing and resistance to mechanical stress; by making slate laying difficult and making the fit between slates imperfect; and by affecting the aesthetic appearance of the slab [10].