The Yomiuri ShimbunThe total accumulated cost of repairing and refurbishing temporary houses for disaster victims will likely reach ¥78.03 billion through the end of this fiscal year, according to the governments of the seven prefectures where they were built after the 2011 Great East Japan Earthquake.

Prefabricated temporary housing units originally designed to last for up to two years have now been used for more than three years. Numerous problems have emerged as a result, including leaking roofs.

An expert panel from the Cabinet Office will begin reexamining the period of use and other aspects of the temporary houses to prepare for future disasters, including a huge earthquake predicted along the Nankai Trough off the Pacific Ocean.

After the Great East Japan Earthquake, local governments in the prefectures of Iwate, Miyagi, Fukushima, Ibaraki, Tochigi and Chiba built the temporary houses based on the Disaster Relief Law. Temporary houses were also built in Nagano Prefecture for victims of another quake in the northern part of the prefecture, which occurred just after the Great East Japan Earthquake.

A total of 53,194 temporary housing units were built in the seven prefectures at initial construction costs totaling about ¥290 billion. The units in Chiba, Tochigi and Nagano prefectures were dismantled as of the end of May this year. Currently, 93,017 people live in 42,590 temporary housing units in the remaining four prefectures.

The law stipulates that temporary houses will be usable for two years and have a per-unit acreage of about 30 square meters. The assumed construction cost per unit was about ¥2.39 million at the time of the Great East Japan Earthquake.

Many of the temporary houses have similar structures to the prefabricated offices at construction sites. They are zinc-roofed and their walls are thin.

Measures to cope with cold weather were especially insufficient. After construction was completed, additional work was done at the request of residents to reinforce heat insulating materials in the walls and double-layer windows.

Total costs from fiscal 2011 to 2013 in the seven prefectures stood at about ¥73.18 billion. In Iwate, Miyagi and Fukushima prefectures, the initial construction costs and the additional work as of January 2013 reached a combined average of ¥6.79 million per unit.

Temporary housing residents are expected to relocate to publicly run housing units for disaster victims. But only 8 percent of the necessary units have been completed, meaning the temporary houses will be used for the foreseeable future. This could present a problem, since some temporary housing units have started to tilt because of weak soil, and residents are increasingly complaining of such problems as leaking roofs and mold.

The prefectural governments of Iwate, Miyagi and Fukushima allocated a total of about ¥4.86 billion for repairs and other additional work in their fiscal budgets this year, and extended the period people can live in temporary housing to five years. These measures mean necessary repair costs will likely continue increasing.

To extend the durability of the temporary houses, their foundations must be rebuilt using ferro-concrete. But this alone will cost ¥300,000 to ¥400,000 per unit.

If a Nankai Trough quake occurs, about 400,000 temporary housing units will be necessary in the eight prefectures that presented forecast figures, according a The Yomiuri Shimbun survey in December last year.

Consequently, the Cabinet Office panel, which handles how the central government should assist disaster victims, is set to submit proposals about temporary housing for disaster victims.