Impact of Elevated Temperatures on the Integrity of PIR-Core Roof Sandwich Panel Connections

The article presents an evaluation of the behavior of joints in roof sandwich panels with a PIR foam core, under conditions of short-term exposure to high temperatures. The aim of the study was to analyze the temperature field distribution within the joint and to investigate how a slight unsealing of the joint by approximately 3 mm affects the thermal insulation. Experimental studies using thermography and numerical analysis made it possible to determine the impact of slight joint gaps on the temperature distribution on the surface of the panels. The temperature difference between the reference areas and the areas exposed to fire did not exceed 1 °C. Using the finite element method, numerical models of joints with a gap of up to 6.81 mm were created. The thermal transmittance values ranged from 0.187 to 0.196 W/(m²·K), and heat flux density at a 102 °C difference from 19.237 to 20 W/m². Even with slight panel separation, the joint still meets the requirements for insulation and fire resistance. Short-term exposure to 100 °C caused no damage, except from ~1 mm local PIR foam melting, which is harmless. Proper roof installation, in accordance with the manufacturer's guidelines ensured the tightness and thermal resistance of the roof.