The Tokyo Metropolitan Government is considering introducing regulations that would relax floor-space ratios when redeveloping old apartment buildings in the city. This would allow for the additional space to be sold by a real estate developer, which would help to cover the costs of redevelopment.
The target of the revision is condo-style apartment buildings that were built to the old earthquake codes (kyu-taishin). The major change to earthquake codes occurred in May 1981, with buildings built after this date meeting the current codes. Due to the time period from construction to completion, there are some buildings from 1982 that may have been built to the old ‘kyu-taishin’ codes.
The current revision under consideration by the Tokyo government would provide a specified increase to the maximum allowable building size for a block of land. E.g. an existing floor area ratio of 300% may be relaxed to 400% if certain requirements are met. The revision could be introduced this year. The city and local wards will designate districts where the revision can be applied, which means some neighbourhoods may be excluded.
Condominiums have a number of owners, making it difficult to reach agreement on redevelopment. Of the small number of successful redevelopment projects, they have all been in good locations and have been replaced with larger buildings, with the extra floor space sold by the developer of the project. Redevelopment stalls when the existing building is already at its maximum size for the land, when owners are elderly and prefer to continue to live in their current apartments, when there is not enough money saved up in the building repair reserve fund to cover construction costs, and where the building is in an inconvenient location.
There are as many as 12,000 condo-style apartment buildings built to the older kyu-taishin earthquake codes in the Tokyo metropolitan area, representing a little over 20% of the 53,000 condominiums in the city. Kyu-taishin buildings are designed to withstand and not collapse in an earthquake producing a shindo-scale intensity of up to upper 5 (note: the Japanese shindo scale represents seismic intensity levels and is different to earthquake magnitude), but pose a risk of damage or collapse in earthquakes with shindo-scales of 6 and above. The 2011 Tohoku earthquake produced a shindo-scale of upper 5 for Tokyo and lower-to-upper 6 for Sendai City, while simulations for a Tokai earthquake predict a shindo-scale of upper 5 for Tokyo. In the 1995 Great Hanshin earthquake, 8.4% of kyu-taishin buildings and 0.3% of shin-taishin buildings suffered serious damage.
In 2013, a new rule requires that owners of pre-1981 buildings for public use, such as department stores and hotels, over a certain size are obligated to carry out earthquake resistant building inspections, with the results publicised on local government websites.
Areas with the highest number of kyu-taishin condominiums:
 Setagaya-ku: 976 buildings
 Minato-ku: 845 buildings
 Shibuya-ku: 786 buildings
 Shinjuku-ku: 759 buildings
 Ota-ku: 666 buildings
Source: The Nikkei Shimbun, April 26, 2017.