Environmental Product Declarations (EPDs) play an important role in documenting the environmental impacts of building products, particularly reclaimed components, yet their methodologies for allocating impacts remain unclear. This study evaluates the methodology in EPDs for reclaimed components to support the development of harmonised frameworks in EPDs and Life Cycle Assessment (LCA). A systematic analysis of 23 EPDs revealed an increasing trend in EPD publications for reclaimed building products, reflecting a growing industry focus on reuse and transparency in environmental reporting. However, variations in the interpretation of standards, such as EN 15804, were observed, particularly regarding the End-of-Waste (EoW) state and impact allocation for reuse. Current EoW criteria are primarily designed for recycling, creating ambiguity in how reclaimed components are classified and when transitioning into a new product system. The findings underscore the need for harmonised guidelines that explicitly address reuse-specific scenarios and align allocation practices with the modularity and polluter-pays principles to enhance consistency and transparency in environmental reporting. While the observed allocation practices aim to ensure completeness by accounting for all relevant processes, they may inadvertently disadvantage reclaimed elements by making them less competitive than new products. Thus, quantitative analyses of allocation scenarios are recommended to prevent the disadvantageous treatment of reclaimed components, ensuring their competitiveness in the construction sector.