This paper is a continuation of the study examining the long-term use of the main halls of temples throughout Japan that are not designated as cultural property by the national government, and the factors thereof.
There are examples of major disasters being experienced during long-term use, and it is essential to conduct maintenance and repairs for the long-term use of old main halls. In this paper, we examine the impact of not only the type of building and era of construction of current main halls, but also factors in structural issues of current main halls, maintenance and repairs, disaster mitigation measures, and advisors on long-term use of current main halls. The following information was revealed.
(1) When comparing three types of buildings, the expected usage period tended to be longer in A. Regional cultural property, but it was found that structural issues were unrelated to the type of construction. Although structural issues were generally found not only in A. Regional cultural property, but also B. No reconstruction and C. Other, they were resolved in all building types by repeated repairs, suggesting that this leads to long-term use.
(2) Structural issues in wooden main halls have gradually decreased in the 70 years since the war, and the rate of structural issues in pre-war construction including reconstruction in the Edo Period remains unchanged around 80 percent. Structural issues in current main halls may be considered to be a result of long-term use. The expected usage period in the future differs by 60 years depending on whether or not there are any structural issues, and it could be said that structural issues need to be resolved to enable long-term use in the future.
(3) Current main halls (of wooden construction) face aging, etc. of roofing materials and structural materials. Furthermore, causes of structural issues include deterioration due to age, leaks, humidity, ventilation, foundations and termites, and many have complex factors. However, deterioration due to age that has a gradual impact over time could be seen to be a phenomenon that occurs uniformly across all buildings left without maintenance and repairs. Therefore, the removal of human problems such as roof maintenance and repairs, etc. are required for long-term use.
(4) Earthquakes are the type of disaster most commonly experienced in current wooden main halls, and damage included cracking and flaking of walls, collapsed roofing and tiles, inclination of entire buildings and inclination of columns. Furthermore, disaster mitigation measures include the reinforcement of columns and crossbeams, seismic diagnosis, establishment of new walls, use of more lightweight roofing materials and reinforcement of lattices, and 40 percent of seismic diagnoses only involved diagnosis. The motivation for implementing measures to address disasters was more preventative than due to experiencing a disaster, but the overall rate of implementation was not high at only 36% of all temples.
Advisors for measures to address disasters in current wooden main halls were temple and shrine carpenters, architects, construction companies and ordinary carpenters, and the rate of implementation of seismic diagnosis was high for temple and shrine carpenters.
Meanwhile, all items were implemented less frequently by ordinary carpenters than by other occupations, and ordinary carpenters were consulted most frequently about measures in older current main halls.
The study is based on a questionnaire survey of priests, and does not conduct specific examination of examples of renovation of current main halls by temple and shrine carpenters and ordinary carpenters. In future, examining the effectiveness of renovation including structural stability and the preservation of cultural value based on multiple specific examples of renovation is believed to be an important perspective.