The disposal of construction and demolition waste will have an impact on the environment. However, the currently limited research on the end-of-life stage waste is too general lacking separation and comparison of different material types. This study focuses on the end-of-life stage to assess two primary construction materials (wood and steel) and an office building, used as a case study. This study is performed applying life cycle assessment (LCA) and used Athena software to assess the impact of both materials. The software quantifies the environmental impact of two materials into nine categories, including Global Warming Potential, Acidification Potential, etc. The results of this study show that steel generates more impact than wood on the environment. In the future, the results of this study can provide valuable information about the environmental impact of wood and steel materials to reduce the environmental impact at the end-of-life stage.