Apartment House on Volcanic Land

It started at a large housing complex in Yokohama. Some residents found a gap between the same floors of two connected buildings. It was proved to be caused by leaning of one of the two buildings with false basic construction. The constructor had been fabricating data of basic structure underground. Within weeks, such unstable buildings were found in all over Japan. Ministry of Land, Infrastructure, Transportation and Tourism embarked on investigation.

On the volcanic land with frequent earthquake like Japan, constructor ties the basis of a building to bedrock underground with a number of piles. In the case of condo building in Yokohama, 6 piles out of 473 did not reach the bedrock. A supervisor of Asahi Kasei Construction Material reported wrong data about piles, as if all piles had reached bedrock. The false data were mainly found in piles driven at the last period of the construction.

The company was in charge of the same basic construction for over 3,000 buildings in Japan. The parent company, Asahi Kasei, known as producer of chemical materials including Hebel House and plastic wrap called Saranwrap, revealed that the supervisor in the Yokohama building had been in charge of 41 constructions in central Japan. The company started detailed investigation about the data of basic construction of all buildings they dealt with.

Residents were frustrated with unexpected fabrication of construction data. Most of them are owners of each room, who made the most expensive purchase in their lifetime for raising kids or comfortable post-retirement life. The developer of Yokohama building, Mitsui Real Estate Residential, is accumulating meetings with the residents about details of data fabrication. The company indicated possible compensation with total rebuilding, which would cause a huge cost.

If other inclination of building were revealed one after another, it will cause fatal damage on Asahi Kasei with great amount of compensation on it. Credibility on major developers will also decline, because personal decision of owning a house cannot be made so many times in one’s life. The impact of inclining of a luxury condo building in Yokohoma is spreading immediately to all over Japan.

MLIT launched an internal meeting to research the fact and required Asahi Kasei submitting data of their all buildings in these ten years. A fundamental question is, however, whether the method of construction to connect building with bedrock is viable in terms of cost and technology on this land. While collective house is convenient in narrow volcanic country, its side effect is not thoroughly cultivated.