Addressing the issue of building re-use, this paper reports on the development  of a re-design tool, which aims at helping students and novices (and even  experienced architects) in understanding design decisions that have steered  existing re-design projects. Furthermore the tool tries to support designers in  using this understanding in their own design projects. The paper starts by  situating the re-design tool within the overall research setup, and continues by  motivating the observations that have led to developing this tool. The core of  the paper describes the re-design tool itself and illustrates it with a concrete  example. Finally, the tool is framed within the wider context of (architectural)  design research, so as to explore where the tool accords or collides with  generally accepted design theories.