| c) History of preservation/conservation | Wooden structures require careful routine maintenance control to ensure proper conservation, beginning immediately after construction. The buildings of Himeji-jo have been maintained and repaired by the authority of the castle lords ever since the castle was constructed. In particular, special care has been given to the Dai-Tenshu (the donjon). The castle lords investigated both vertical and horizontal displacement every twenty to thirty years and reinforced or repaired the buildings as required, based upon the results of these investigations. In the repair works of 1656, 1692, 1700 and 1743 the vertical and horizontal distortions were measured, the buildings were reinforced by such means as the addition of braces and supports, and the roof tiles were replaced. After the birth of Japan as a modern nation toward the end of the nineteenth century, the buildings of Himeji-jo became the property of the national government. In 1910 temporary reinforcement work was required in order to stabilize the structure of the donjon. With the enactment of the National Treasures Preservation Law in 1929, the protection of cultural properties, which until then had been limited to ancient shrines and temples by the Ancient Shrines and Temples Preservation Act of 1897, was extended to include castle architecture as well. Under this law the buildings at Himeji-jo were designated as National Treasures in 1930 and 1931. Since the buildings were in need of fundamental repair just at this time, it was decided to repair the entire castle structure over a period of thirty years beginning in 1934. This repair work was performed under the direct supervision of the national government. For this conservation project, conservation architects were stationed permanently at the site to supervise the operations and to carry out general academic investigations of the entire castle. Moreover, a committee of experienced specialists was established to determine the methods of repairing the buildings. One of the most notable conservation achievements of this time was the repair of the donjon. This repair work involved dismantlement of a large wooden structure second in size only to the Todai-ji Kondo (the Great Hall of Buddha) in Nara, the world's largest historical wooden building. In addition to investigations of the structure and design of the castle, investigations were made on the condition of damage (including vertical and horizontal displacement, a special problem with large structures), on the composition and geological features of the foundation ground, and on the methods of reinforcement required to correct the structural flaws. These investigations showed that there was a considerable degree of vertical and horizontal displacement and that the displacement was primarily the result of settlement due to insufficient soil bearing capacity. It was also made clear that many braces and supports had been added previously for reinforcement and that some of the window fittings and door fittings had been changed. To solve the bearing capacity problems, it was decided to construct a reinforced concrete foundation which would be supported directly by the underground bedrock. The reinforcement supports which had been installed earlier were removed and replaced with new steel reinforcement connectors placed in inconspicuous positions in order to re-create an appearance as close as possible to the original condition. Those doors and windows which had been changed during earlier repairs and about which there was enough remaining reference material were restored to their original condition. Similar detailed investigations were also made for the other buildings as well, and repairs were carried out based on these findings. Documentation on the details of the restoration work, including investigation results, drawing, and photograghs, was prepared and published by the National Commission for Protection of Cultural Properties (the predecessor of the present Agency for Cultural Affairs). For all of the repaired buildings, large-scale detailed record drawings were prepared to show the condition both before and after the conservation work, and these drawings are permanently on file at the Agency for cultural Affairs. The number of drawings of the buildings in the Himeji-jo has now reached approximately five hundred sheets; several examples are provided as Additional Reference Materials 4. Furthermore, along with the conservation work itself, steps were taken to improve fire safety management practices by establishing fire prevention facilities such as fire detection systems and water fire extinguishing systems. In 1964, upon completion of the conservation work, the national government designated the City of Himeji as the organization in charge of the management of the group of buildings(custodial body). From that time until the present all repairs for the purpose of maintenance, such as repair of roofs and wall surfaces, have been made whenever necessary. Appendix 11: Chronological table of conservation works Appendix 12: Plan indicating the buildings for which conservation work has been completed Additional Reference Materials 4: Detailed record drawings |
