Abstract.In article the problem of durability of elevations of large-panel technology buildings is analyzed. In Poland this is a serious technical issue because it has an impact on the whole country. Heat loss through infiltration, the possibility of mold growth and general breakdowns are also reasons for increasing user discomfort. In article the results of the diagnostics presented in the literature and the authors' analysis and diagnostic results are presented. Article also presents conclusions regarding to the durability of applied insulation systems ETICS and the need to strengthening the layers connections of the facade panels.

Many buildings have considerable thermal bridges at the junction of balcony slabs with walls. To achieve the new EU directive targets related to energy efficiency, greater attention should be paid to such design details. This study analyzes the efficiency of traditional balcony slab modernization methods, the use of modern insulation materials and a new alternative system: an added self-supporting light balcony system (LKBD) in retrofitted large-panel buildings. The main objective was to capture cost-effective renovation methods from both the heat loss reduction perspectives and risk of surface condensation. The analyses, carried out in four buildings, have shown that at current costs, the thermal modernization of balconies is not economically efficient (SPBT>98.4 years). However, it is necessary because leaving the balcony slabs without insulation or only insulating them from the bottom carries the risk of surface condensation. The most cost-effective renovation method is to insulate the balcony slabs from below and above with the thickest possible XPS layer (SPBT = 98.4 years; 107.4 years). Replacing XPS with modern material increases SPBT by almost 50%, for the LKBD system, SPBT = 269.2–281.5 years. More favorable energy and economic effects related to the reduction of balcony thermal bridges were achieved in the wall with lower insulation.

This article presents a non-invasive tests report of precast cantilever balcony support in OWT-67 large-panel system. During field testing, the balcony's reinforced concrete structure was subjected to radiometric analysis in the context of thermal energy distribution as well as from the point of view of mycology - to the possible presence of spores of domestic fungi. The temperature distribution tests carried out by means of the electromagnetic wave detection in the infrared spectrum clearly confirmed the significant losses of thermal energy caused by the effect of the thermal constructional bridge located in the balcony. Mycological diagnosis was carried out using the rapid test of the Mycometer bacterial meter, which allows fluorimetric evaluation of the presence of the enzyme presence in filamentous fungi. In the conducted study, no spores of the house mushroom were found on the inside surface of the Z-type balcony supporting beam as a place where condensation of water vapor may occur. The summary also presents a design solution that allows to eliminate this physical problem.

The work touches on the national security issues of large-panel buildings from the point of view of settlement of the building on the ground. Displacements of the structure in the level of foundation of the building structure cause the secondary distribution of stresses, thus the possibility of structural scratches of internal prefabricated plate elements. The original model FEM of the construction of the large-panel building system Wk-70, which was built for research purposes, allowed the approximation of the phenomenon contained in the title of this work. Awareness of the safety of the construction of buildings implemented in large-panel technology is very important and constitutes a significant overtone, not only structural, but also general social.

The paper presents the results of FEM computer analysis regarding cracking of the wall prefabricated element. The proprietary coating model of the Wk-70 System large-panel building construction was used. For analysis, a construction diaphragm has been separated that is integrally connected to the vertical communication structure. Modeled through the scratch in the attic wall and compared with the wall model without damage. By building the shell model, a real and transparent picture of the static work of the structure was obtained, distinguishing zones: focus, redistribution, compensation and neutralization of stresses, whose genesis results from imperfection - scratches in a reinforced concrete composite. For the first time, the author introduces his own method of assessing the safety status of large-panel buildings - by the States Continuum Method.