Outline of Prefabricated Housing in Japan

Overview of Prefabricated Housing in Japan Jan.２０.２０１５ JUDANREN (Japan Federation of Housing Organization) Junichi Goda 1

Contents

Prefabricated Housing in Japan

1 What’s prefabricated housing? 2 History 3 Construction results 4 Classification of construction methods 5 Characteristics 6 Construction of temporary houses in times of disasters 7 Future Direction 2


1 What’s prefabricated housing?

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1 What’s prefabricated housing?


Prefabricated housing is a system of producing housing structural members (columns, beams, roof trusses, walls and etc.) in a factory and assembling them on the building site. →Quality control + Reduction of constructing term

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2 History

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2 History -1


After WWⅡ House Shortage was about 4.2 million units →the need to promote construction of many houses. 1960s • Japan Housing Corporation and some construction companies collaboratively developed middle-rise housing with PC (Precast Concrete Panel) methods. • Government made standard housing plans for public housing →Those methods enabled public housing to construct many houses.

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2 History-2


1960s(continue) ・Many companies joined housing business. ・Some of the companies developed new housing system and began to sell people detached low-rise prefab houses.

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2 History-3


1970s • Various PC methods were developed for better design and high-rise buildings. • Government made some development projects for prefab housing of better performance and lower cost. • Government started the assessment system of prefab housing for customers.

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2 History-4


1980s-1990s • JPA (Japan Prefab Construction Suppliers &Manufacturers Association) started PC component quality certification project and PC structure inspection system. • In 1995 the Great Hanshin Earthquake occurred, when it was proved publicly that prefab houses were very tough against the big earthquake.

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2 History-5


2000s• JPA started the system for certifying qualifications of PC construction management engineers. • Some prefab housing companies started overseas projects, such as in China, southeast Asia, Australia and the US. • Prefab housing companies have focused on high performance -- resistance against earthquakes, energy-efficiency, design for elderly residents, and durability.

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3 Construction results

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3 Construction results-1


1963 - 2014 about 9 million prefabricated houses have been constructed in Japan. Constructed Units(1963-2014) Total 9,097thousand

concrete , 1,605

tend of annual construction

wooden, 1,534

Iron &steel, 5,958 ↑ Peak year 1993

3 Construction results-2


Recently around 150,000 prefabricated houses are constructed annually in Japan. Years Prefabricated houses All houses

Ratio

recent annual construction (prefab and non-prefab)

units

ratio

(constructed units) (constructed units) % 2004

159,930

1,189,049

13.5

2005

156,254

1,236,175

12.6

2006

160,347

1,290,391

12.4

2007

145,360

1,060,741

13.7

2008

154,427

1,093,519

14.1

2009

125,924

788,410

16.0

2010

126,770

813,126

15.6

2011

126,770

834,117

15.2

2012

132,244

882,797

15.0

2013

146,402

980,025

14.9

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

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4 Classification of construction methods

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4 Classification of construction methods-1


A Iron & steel prefab housing

B Unit prefab housing A

B

C

D

C Wooden prefab housing

D Concrete prefab housing 15



A Iron & steel prefab housing Steel frame comprises the main structural members, using wall panels with steelframe columns and beams. Production in factory →

Work on building site

→

Completion

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B Unit prefab housing Modules (units) made with frames of steel or wood are produced at the factory and connected together at the construction site. Interior items are installed at the factory. →The ratio of industrial production is very high. Production in factory ↓


→

Completion

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C Wooden prefab housing The structural members are panels and other items made of wood. Production in factory

→


→

Completion

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D Concrete prefab housing The main structural members are PC panels and other PC components. It is used for low-rise housing as well as middle and high-rise housing. Production in factory ↓


→

Completion

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5 Characteristics

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5 Characteristics-1


A There is no deviation in quality and a high degree of precision is achieved. -strict quality control in the factory using cutting-edge technologies such as computers and robots.

B Simple and high quality of construction work is done on building site, because components are standardized.

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5 Characteristics-2


C Construction period is shortened largely. - not to depend on workmen’s skill. little construction work on site. Customers can get their home earlier. D The reduction of the construction cost can be realized. - mass purchase of materials and production standardized construction work. E Valuable technologies and performances can be adopted easily. - Technologies and performances that are hard to adopt on construction site can be adopt easily in the factory, such as special processing and painting. 22

Examples of prefabricated houses in Japan

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6 Construction of temporary houses in times of disasters

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6 Construction of temporary houses in times of disasters-1 Prefabricated Housing in Japan

・We construct temporary housing for victims of disaster on the basis of request from the governor of each prefecture. -recently Great Hanshin Earthquake, Mt. Usu eruption, Great East Japan Earthquake ・ JPA has agreements with all of Japan’s 47 prefectures on construction of temporary houses in times of disaster.

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6 Construction of temporary houses in times of disasters-2 Prefabricated Housing in Japan Year area

disaster

construction units

2012 Iwate, Miyagi, Fukushima, Tochigi, Ibaraki, Chiba, Nagano

Great East Japan Earthquake

2007 Ishikawa

Noto peninsula earthquake

2007 Niigata

Niigata Chuetu offshore earthquake

2005 Fukuoka

Fukuoka west offshore earthquake

230

2004 Niigata

Niigata heavy rain

400

2004 Niigata

Niigata Chuetsu earthquake

2000 Hokkaido

Mt. Usu eruption

1995 Hyogo, Osaka

Great Hanshin Earthquake

43,260 334 1,222

3,460 734 35,287 26


7 Future Direction

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7 Future Direction


A Contribution to global environment

B Design for elderly society A

B

C

D

C Longer longevity of houses

D safety against disasters 28

Thank you very much for your attention.

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