An article in Shukan Gendai states that according to the real estate industry about one-fifth of all condominiums throughout Japan “probably” violate current local building codes. The vast majority of these violations are time specific, meaning that they didn’t violate codes when they were built. Laws were changed after they were constructed, and while there is no requirement that the condos have to be rebuilt to adhere to the new codes, the situation is still bothersome for those who live in them. Basically, it makes it even more difficult for the current owners to ever sell them.

Most of the violations have to do with so-called capacity rates. In the sixties, when mid-rise (10-15 stories) condos first became popular in major cities, there were no laws about the right to sunlight, but as more and more of these buildings were constructed, neighbors complained about having views blocked. Capacity rate laws were later enacted that limited the height of a building in comparison to the land on which it’s built and the subsequent floor area of each story. Consequently, a lot of older condos, especially those in the centers of cities, where property values are still high, basically violate these new laws. One non-profit housing organization estimates that approximately 90 percent of all condos built before 1981 in major cities are in violation of local laws.

Condo owners pay monthly fees for the repairs to the overall building, and it is assumed that this money may someday go to rebuilding the entire condo, but in the case of buildings that violate capacity rate laws, these buildings could only be built smaller, meaning some owners would have to leave or everyone would have to agree to smaller units. Consequently, little if any real improvements to old buildings is being done, unless a developer decides to get involved. One housing research group says that only 130 condo complexes have ever been rebuilt in Japan. The end result are “slum mansions”–derelict condos that the owners have abandoned because they can’t get the price they prefer. According to Gendai, there are even slum mansions in high-rent areas like Tokyo’s Minato Ward.