Countermeasures against flood damage of buildings and their applicability

In Japan, devising ways to live in areas with a possibility of flooding, to regulate and guide buildings and land use should be considered to respond to future climate change. This article investigates the cost-effectiveness of flood damage countermeasures at the building and site level based on the flood risk of the location. In the research, 3 cases were assumed; (1) when constructing a new wooden detached house, (2) when renovating an existing condominium, and (3) when a business office moves into the first floor of a RC building and a model examination of flood countermeasures was carried out and demonstrated. By calculation and comparison of “average expected payback period”, it was found reasonable to first prepare for flooding at a minimum of 30 to 50 cm above ground level, and then to consider countermeasures in stages for greater flooding depths.