The role of maintenance and renewal work is getting its importance in Japan since we have less new construction and more buildings to keep as stocks. Public spaces covered with large roofs, such as covered baseball stadia, are good examples. The average of service time of the existing buildings is 42 years while that of the lifetime of already demolished buildings is 33 years. Many of the Japanese public spaces with large roofs are facing to the big long period of renovation. We need to develop better schemes to use the existing buildings as the useful stocks of the society.[This abstract is not included in the PDF]