Reuse of building materials can provide environmental benefits that are essential for the sustainable management of resources. However, reuse of a building material presupposes that it is suitable for reuse, in other words that it does not impair the quality of the finished building, compared with using new materials. This guide provides advice about how to assess building materials for reuse. The guide is part of the research project, REBUS (REuse of Building materials – a USer perspective ). The objective of the research project is to develop new knowledge to enable the more effective reuse of building materials.