Seijiro Yamada from Matsui Kensetsu
View of the courtyard from a room with a piano The window frames were changed from aluminum window frames to steel.
We talked with Seijiro Yamada from Matsui Kensetsu.
Q: What kind of restoration was carried out in this renovation work?
Yamada : In restoration and renovation work, presently used materials are repaired, missing materials are procured, and similar materials are used if necessary materials cannot be obtained. In this restoration and renovation work, we reused materials that had been used for the buildings. It was not a usual demolition work, so we dismantled the buildings while numbering each material.(continued in the lower column)
Q: What is the meaning of restoration and renovation?
In restoration and renovation work, it is important to restore a building to its original state. This time, we needed to restore the buildings to the sate in the 1960s, so aluminum window frames were replaced with steel window frames that were used in the 1960s. Although aluminum window frames are easy to use, it was necessary to changed them back to the original materials and restore them to the state at that time. Regarding the walls with crushed pieces of agate in Choyo-no Ma, since agate is a very expensive material, we did not demolish the walls, but abraded the surface. We removed the agate using a file-like tool, and washed the walls. We procured new agate and applied it to portions of the walls where agate was peeled off. We had trouble finding materials similar to the original agate. (continued in the upper right column)
Q: What was the central purpose of this restoration and renovation work?
The central purpose was to execute the earthquake-proofing work for the wooden building and to restore the buildings to the sate in the early 1960s. The most important issue was that the result of the earthquake-proofing work could not be confirmed. Since earthquake-proof walls were used, reinforcing wood was contained in the walls, so the walls thickened. The wooden building is the sukiya style of building. The original walls were made very thinly, so it was necessary to adopt a construction method that did not make the walls look thick. In order to perform the earthquake-proofing work while making the walls look thin, the number of nails should be increased. If a whole wall needs to be reinforced, many nails should be driven around the wall. In this renovation work, the wall was divided into about six portions, and each portion was nailed, so the number of nails was minimized. In this way, the walls' strength to withstand earthquakes was assured.
Q: What was difficult to perform the seismic reinforcement work for the cultural property?
For general seismic reinforcement work, foundation excavation is conducted, and a building is reinforced by steel frames. However, since this building is a cultural property, we could not use that method. Therefore, we adopted a method to build steel frames into the border between the foundation and the building. Structural steel called "Earthquake-Proof Brace" was built into the ceilings, and the back of the roof was reinforced by wooden diagonal beams.
Workers who were in charge of the work also said that they had never seen or used such a material before, and that it was a good experience. Since the Great East Japan Earthquake occurred during the period of this demolition work, it warned us that we should adopt a method that could withstand such a disaster.
Seijiro Yamada from Matsui Kensetsu