Over several decades, insulation materials have served the crucial role of meeting thermal performance standards for buildings. However, a contemporary challenge arises as an in-creasing number of these aged insulation materials are released during demolition or renovation. Regrettably, these materials often end up in landfills or incinerators, even though they are usually not at the end of their potential lifespan. To tackle this challenge, there is a growing need to explore the potential of reusing insulation materials. The key challenge lies in understanding the dismantling process, the performances after ageing, and identifying optimal reuse applications in new constructions with some level of quality control. This necessitates a comprehensive investigation into the durability of naturally aged insulation materials, focusing on commonly used products in the existing building stock, such as synthetic foam insulation. This paper focuses on evaluating the performance of naturally aged polyurethane (PUR), polyisocyanurate (PIR), and extruded polystyrene (XPS) insulation retrieved from cavity walls, pitched and flat roofs. Assessment of both damage and performance reveal a high potential for reusing these synthetic foam insulation materials, as minimal degradation was observed. These novel findings underscore the potential of reusing insulation materials, thereby promoting circular building and reducing the ecological foot-print of the construction industry.