Written by By Tom Morris, CNN

Whereas western architectural tradition aspires to permanence -- an Englishman's home is his castle, after all -- Japanese architecture is focused on flexibility. A close harmony with the natural world combined with acute awareness of its dangers has cultivated a special approach to building.

Sarah Ichioka, a Japanese-American urbanist currently based in Singapore and former director of the Architecture Foundation in London, explains how earthquakes and tsunamis forge a unique context: "This unstable environment has created a culture that accepts cycles of destruction and renewal as a natural part of life."

Man-made disasters such as nuclear attacks and the Fukushima disaster have had an effect too. "Detachment from the illusion of physical permanence seems a very sensible approach to architecture," she concludes.

These dangers combined with hefty inheritance tax and rapidly updating technology has led to a building culture known as "scrap and build." Rather than renovate, remodel or re-use, the Japanese have long favored simply knocking down and starting again. It is the land of the disposable building, where a 20-year-old home is considered old.

It is no wonder that Japan now has 11 times as many architects per capita as Canada, five times as many as the UK and over seven times as many as the US. The more you build, the more architects you need and, as a new exhibition at the Barbican Art Gallery in London shows, the more groundbreaking the architecture becomes.

Exhibition features more than 40 architects

"The Japanese House: Architecture and Life after 1945" looks at extraordinary residential architecture built in postwar Japan up to the present day. More than 40 architects feature in the exhibition, including masters such as Tadao Ando, Kenzo Tange and Toyo Ito and younger talent including Sou Fujimoto and Ryue Nishizawa of SANAA.

"The roots of the exhibition are in the Second World War," explains the show's curator, Florence Ostende. "It was a crucial moment for architects to rethink the domestic house and how we live. They were facing the massive trauma of losing the war and they had to rebuild the country. Forty percent of Tokyo was bombed out."

The world's first earthquake resistant building

Tokyo was slowly rebuilt under enormous pressures of population density and a struggling economy. It set a precedent for imagination in the city, which has endured ever since.

In 1966, Takamitsu Azuma built a tower house in the city on a triangular 20-square-meter plot, with staircases acting as boundaries between the rooms instead of doors. Toyo Ito built a residence in 1984 using wooden window frames from previous projects and, in 2011, Sou Fujimoto designed a house encased in glass with no internal walls.

This crystal universe actually exists

"In Tokyo, you don't have the rule that houses have to look the same. There's no aesthetic regulation," explains Ostende. "Architects are free to invent the forms and shapes that they want to build."

Most of the homes in the exhibition demonstrate a close relationship with nature. There is a full-scale model of a teahouse in the space, made of charred timber and filled with a woody scent. There is also a full-scale replica of the Moriyama House in Tokyo, designed in 2005 by Pritzker-prize winning architect Ryue Nishizawa of SANAA.

It consists of 10 small units arranged around a garden; the outside space becomes almost a room in itself. "This interspersed quality of the inside and the outside is something that architects since the 1990s have been working with," says Ostende. "Nature, the weather, living organisms and animals all react to the house. It is not just a bunker that is isolated from the outside. It breathes with the rest of the city."

All these special houses require special clients (a film screen in the exhibition wonderfully casts Mr. Moriyama center stage); someone who is happy to live with the world peering in or with leeks growing on their roof. Thankfully, it seems there are as many experimental clients in Japan as there are pioneering architects.

"I want to make day-to-day life an art form. I think architecture is the most exciting commission-based work of art," explains Tsubasa Oyagi, a 37-year-old creative director who is currently working with SANAA on a 100 square meter house for him and his partner in Aoyama, Tokyo. What is it like to design your own home from scratch? "It's fulfilled my wish of wanting to make everyday life a work of art, with the architect realizing this with his own imagination."

Seeing a home as the ultimate consumer good -- a piece of tailor-made art instead of investment asset, as it has is in other parts of the world -- has created this unique industry. As curator Ostende says: "All these people can be empowered by the potential of making their own house."

"The Japanese House: Architecture and Life after 1945," Barbican Art Gallery, London. Until 25 June 2017.