Investigation of the probability of losses in the external insulation layer of residential engineering projects using the weather test.

Increasing attention has been drawn to the delamination of the external thermal insulation layer, which severely impacts the residents' living quality and insurers' claim risks. Therefore, the probability distribution of losses caused by external insulation layer delamination is investigated in this study through weather tests, considering that such delamination occurs due to a bond strength of zero, in order to provide scientific support for the inherent defect insurance (IDI). Using a thin-coat external thermal insulation system with expanded polystyrene (EPS) boards (500*500mm) as the test subject, weather tests were designed to simulate the monsoon climate in China. Bond strength testing was then performed to quantify the degradation level of the insulation layer. The results indicate that bond strength degradation and the initial bond strength under non-load conditions follows logistic distribution and Weibull distribution respectively, with 25% of the test blocks exhibiting Grade I damage. Additionally, the delamination failure probability is counted out 0.164 based on the structural reliability theory. Further analysis indicated that IDI claim frequencies can be approximated through a Poisson distribution using parameter λ, thereby establishing a quantitative model for insurers' premium pricing and risk management. Moreover, the probabilistic patterns of insulation layer delamination were clarified by integrating experimental and theoretical methods, thereby not only addressing a critical knowledge gap in the IDI's loss assessment for external insulation systems, but also directly enhancing the accuracy and reliability of construction quality insurance practices and IDI risk evaluation.