Karmen Peternelj, Sanja Alaber, Miloš Bavec, Stefano Devoto, Stefano Furlani, Goran Glamuzina, Jernej Jež, Tvrtko Korbar, Maja Oven Stanič, Maria Luisa Perissinotto, Fabiana Pieri, Duška Rokavec, Ivan Stanič, Domen Zupančič
In general, we distinguish between two methods of covering roofs – increased and standard overlap.
The laying of roofs with increased overlap has a vertical thickness of 10 to 25 cm, while the standard overlap yields a vertical thickness of 7 to 10 cm. Thicknesses can differ from the stated because stones undergo minimal processing and are not of a constant thickness, width or length. Roofing stones along the eaves are 6 to 8 cm thick and roughly 50 × 70 cm in size. Along the drip edge, double plates (double headlaps) are installed and allow the suitable drainage of precipitation. Dimensions are indicative as they are determined by the availability of material.
In Herzegovina and partly also in Dalmatia, there are roofs where stone plates are laid on roofs in two ways: the edges of the roofing are laid in the direction of the building's edges, while the internal fields of the roof have roofing stones laid at an angle. The angle is generally 45°. Such an execution of the roof surface allows the point drainage of precipitation. Stones can have less processing done to them, i.e. without the finishing of the plate ends. Roofing stones are up to 9 cm thick and roughly 50 × 70 cm in size. Roofs employ multiple headlaps.
A stone roof can be constructed without an additional roof frame
A stone roof can be constructed without an additional roof frame. The roof is thus uniform in terms of materials. The corbelling technique is used for simple buildings such as shepherd's huts, which are common in the Adriatic area and in the Karst hinterland.
One reasonable question to ask concerning the above variants is the insulation. There are two types of heat insulation. In the case of stone-built buildings or buildings with exposed structural elements on the façade, the installation of heat insulation on the exterior side of the walls is an unsuitable architectural solution. Structural elements on the façade determine the architectural expression of the building from the point of view of typology or function, dating of the building and the material processing method. In such cases, heat insulation is installed on the interior side of the walls. The installation of interior heat insulation requires technical adaptations, changes to the architecture of the internal spaces and a partial reduction of areas/volumes of the spaces. Such procedures are often associated with the restoration of the load-bearing structure, the optimisation of installations and the assurance of suitable fire safety. When installing new installation in the building, we do not recommend making holes or channels in the stone walls to accommodate the installations. Such destructive procedures weaken the wall and the structure. We recommend that the ducting for the installation be installed on the outside surfaces (on the surfaces of walls) and then covered with suitable heat insulation.
In cases of simple buildings without structural elements in the façade, external insulation of a suitable thickness can be installed
In cases of simple buildings without structural elements in the façade, external insulation of a suitable thickness can be installed. Owing to the thickening of the building shell, individual elements must be moved to a new position in order to be in the same plane as the façade. Such construction is technically demanding as it is difficult to avoid thermal bridges. The relocation of elements (sills, massive window frames) from walls to new positions weakens the stone structure itself. They are therefore more of an exception and not recommended.
These interventions on older buildings must ensure suitable energy consumption. Moisture is a frequent problem in older buildings as it penetrates from the outside (backfilled parts) and from the foundations. Years of moisture in the structure changes the properties of the materials. The building must be dry prior to installing heat insulation. The building must have suitable hydro insulation and comprehensive ventilation. Architects and expert services from various fields must therefore determine suitable solutions for these problems. Mere compliance with the laws and guidelines in the area of energy efficiency only represents one aspect of designing a suitable living environment for a modern standard of living.
In addition to stone-covered and completely stone roofs, there are many more different architectural elements in the area where platy limestone is found. These elements are often of secondary importance, but have a higher aesthetic value. When studying these elements, we have discovered their true value on countless occasions and we link them to their function on the building.
Water drainage from the roof is not left to chance. The area of the Adriatic and its hinterland has dry summers and precipitation-abundant months during the cold part of the year. Fresh water is less frequent here than elsewhere, which makes it a valuable commodity. Rainwater is often channelled from roof gutters into underground rainwater tanks.
Roof openings on stone roofs are limited to the layers of roofing stone plates. They are intended for attic ventilation. Larger openings are made using dormers.
