Design Strategies for Floor Plan and Furniture Arrangement to Reduce Flooding Damage in Housing

In recent years, flood damage in Japan has intensified due to the effects of global climate change. Flood prevention efforts led by public authorities are no longer sufficient to respond to the increasing frequency of flood events. As a result, it is becoming more important for individuals and households to adopt their own protective measures. Meanwhile, Japan’s aging population has led to a growing demand for barrier-free housing designed to support daily mobility. However, such housing often lacks architectural features suited for flood resilience. This study investigates the feasibility of indoor vertical evacuation to the second floor during flood scenarios, particularly when water enters through the entrance. Six barrier-free residential floor plans were analyzed using graph-theoretical indicators, including Total Depth (TD), Mean Depth (MD), Relative Asymmetry (RA), integration (i), Weighted Path Length (WPL), and Flood Critical Value (FCV). Both spatial configuration and furniture placement were evaluated for their impact on evacuation performance. The findings indicate that floor plan layout, staircase position, hallway connectivity, and furniture arrangement all play a critical role in the effectiveness of indoor evacuation. This underscores the importance of evacuation-informed residential design, which integrates architectural planning and interior layout to improve flood resilience at the individual level.