Investigation of Conservation Environment for Wooden Architecture in Rock Caves

Measuring the surface temperature of the rock
Measuring the moisture penetration status above the rock
Measuring the surface temperature of the honden

 The Center for Conservation Science conducts investigations for the conservation environment of wooden architecture built in rock caves.

 The Natadera Temple in Komatsu City, Ishikawa Prefecture is a temple of the fusion of the Indigenous Hakusan Faith (the faith for Mt. Hakusan), and Buddhism. Its wooden  honden (main shrine), which is an Important Cultural Property, was reconstructed in 1642 in a rock cave created via natural erosion. In recent years, aseismic reinforcing works have been installed. Since then, moisture condensation has often occurred during spring to summer time, which is problematic because it causes wood decay. Therefore, it is desirable to reduce the frequency of moisture condensation to conserve the shrine and its decoration in good condition.

 To tackle this, the Center is conducting an environmental investigation to identify the occurrence factors of moisture condensation and to determine the appropriate countermeasures to reduce them. Rainwater, outer air, and heat capacity (ability to store heat) of the rocks affect the environment inside the cave. Therefore, the temperature and humidity in the cave, moisture penetration into the rocks, and surface temperature of the rock and the honden are being measured. We plan to pursue our investigation by continuous measurements of environmental data and analysis.

 Moisture condensation causes many problems at many masonry constructions and stone chambers of burial mounds. In recent years in particular, the rise of temperature and absolute humidity in the summer season increases the condensation occurrence risk. There is an urgent need to tackle the global environmental challenges. However, for now, we suggest the achievable countermeasures in everyday management.

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