Dentoh-Isan Preservation of Traditional Building Methods in Japan

by Karl Bareis (adapted from The Wooden Post, vol 11, June 2018).

Building Methods Being Redefined in Japan

When the nation of Japan viewed the devastation and clean-up efforts after the Great East Japan Earthquake of 2011, many people came to recognize the necessity to reduce non-recyclable content in construction. Nearly 100% of new construction materials could NOT be recycled. Whereas the traditional buildings, with tatami, wood and tile, could be quickly cleaned-up without environmental costs, the plastic and chemical remains of the modern construction needed to be carefully filtered and sequestered to protect the environment from becoming polluted with complex chemical residues which mix together producing unknown future effects. The cost of the clean-up after disasters like Earthquakes has become part of the conversation in Japan centering around how to bring about healthy sustainable environments.

Conversely, carpentry everywhere is under pressure to conform with new norms, energy efficiency and adherence to a uniform code of compliance. By insulating us from exterior environment and by introducing manufactured lumber that is covered in layers of finishes we’re changing our fundamental relationships with Nature. Recently Jon Stollenmeyer wrote a note describing how modern Japan has joined the International Building Code (IBC), incorporating universal methods of construction.

…”Japan’s political leaders are under pressure to make building codes more and more ‘energy efficient’ which has also been a move by prefabricated home builders to marginalize the traditional builders even further (in my opinion). The typical relationship to the outside world and therefore architectures’ relationship to that has been far different than the HVAC culture in the US and yet in recent years movement to wards ‘super-insulated’ homes has pushed building codes and threatens to make it impossible to build a traditional wooden framed, bamboo latticed, earthen plaster walled building in a country that is founded on over 1500 years of this architecture (and for good reason).”

In the words of Dentoh-Isan:

“Building a sustainable society with traditional building materials is not only some reconstruction of the past, but rather a formula for “environmental architecture” that suggests “the future of Architecture.” Traditional construction is a technology that uses natural materials that involves trees and soils, and produces less energy and make it possible to build a long-lived home. These natural materials can even be dismantled and reused if necessary”. “Modern buildings are filled with chemicals and it is not possible to dispose of the harmful gas even if it is burned as fuel. Environmental architecture is defined by materials that naturally decompose quickly back into soil. While modern products like linoleum, even if it is set in a wooden frame, is difficult to separate out and therefore likely to become prohibitively costly to recycle and ends up producing only a large volume of garbage for local landfills. “In the case of house-building using the traditional construction methods, because the pieces are produced by cultivation as with the tree and the soil, a lot of material is produced naturally, and a reuse circulation comes about: the trees in the nearby mountain can be produced and reproduced in a natural cycle. After the great East Japan earthquake… more and more people are hoping to live in a small and harmonious environment.”

The Dentoh-Isan movement in Japan has grown in recent years. Disasters and wasteful use of resources have brought the focus back to traditional construction methods that utilize locally harvested forest products and concentrate on structural longevity over convenience. The DentohIsan movement is educating people to recognize that the true cost and value of a home should be considered more carefully. Consideration of the interior environment, free from gases and chemicals, makes a difference to the health of the occupants. Seeing the great swaths of polluted debris that floated out into the oceans and remained in huge piles on the shorelines after the earthquake and tsunami forced the government and politicians to re-evaluate the modern construction industry, thinking of ways to re-invent a “healthy house”, using the knowledge of the past along with materials which can be re-used.

In addition to the philosophy of building healthy homes, the movement has also tackled unreasonable building codes that require substantial re-working of the structure of old buildings in order to comply with current building codes. Japan’s building codes are reflective of the international trend that establishes the principal of rigidness as primary method for code compliance. Within Japan the movement has focused along with UNESCO to assure that traditional methods take precedence, and repairs of historic buildings can follow methods proven locally to be the best for each region.

The Dentoh-Isan movement in Japan seems at first glance to be bucking the trends of architects and builders, pointing out the disturbing facts of indoor pollution, and difficulty for modern society to cast off waste without accounting for long term effect to the environment. They have big ideas, and even bigger dreams, of somehow getting the public to drive the building trades away from careless building practices. By joining the environmental movement to clean building practices, they’ve also begun to breathe new life into the traditional craft of construction. While mainly aspirational in terms of the whole economy, they have gained powerful allies in the trades and with architects….see the recent decision of the Tokyo Olympic Committee to choose a home-grown architect, who promptly announced he would build the stadium using locally-grown trees.

The Movement has many facets, and does have a corollary in our own country, although more and more construction here is designed to be carbon neutral. Certainly as designers we can provide prototypes that are inspired by the concepts of DentohIsan — cleaner, safer, locally-designed to match the climate.

We should find ways to communicate to fellow craftsmen the possibilities presented by Dentoh-Isan, and link up wherever possible to this movement with so many common bonds and aspirations.


Above is the link to the Dento-Isan website (in Japanese only). There are some interesting links to woodcraft, including a lecture by Kuma sensei, the designer of the 2020 Olympic Stadium.