Why do so many Japanese homes have bars over the windows?

Photo of Paul McMahon

Paul McMahon

Founder of TokyoDev
A house with bars over the windows Image: Paul McMahon

If you wander around any residential neighbourhood in Japan, you’ll notice many home windows with bars over them. This seems incongruous with the country’s reputation for safety, and so I sought to answer the question as to why.

“Crime prevention” is the obvious answer. But drilling deeper, why are they popular here in Japan compared to other places like my hometown of Vancouver, which has a far higher rate of residential burglaries than Japan?

My research on the topic identified three factors that may have contributed to their prevalence: window location, the Japanese fire code, and traditional architecture.

Window location

In Japan, bars are most commonly placed over windows in the laundry/washing room, the room containing the actual bath, toilet rooms, and the kitchen. These rooms are often found at the back of the house, and the majority of home break ins occur through such windows. Meanwhile, those windows are mostly used for ventilation, so they’re often left ajar. Furthermore, for privacy reasons, these windows are often translucent. Because of this, bars over such windows aren’t obscuring a view for the homeowner, and provide some measure of security at a minor cosmetic cost.

Fire code

Japan’s fire code makes it relatively easy to have bars on windows. For a residential home, a single floor needs to only have one window that is effective for evacuation or fire fighting. This means a bedroom window could have bars over it, as long as another one on the same floor didn’t.

Furthermore, it is not illegal to have no such windows; in order to make up for the lack of them,he building only needs to meet stricter standards with regards to fire-fighting functions, such as indoor fire hydrants and sprinklers

Traditional architecture

Window bars have been a part of traditional Japanese architecture, taking two main forms: koushi-mado and renji-mado.

Koushi-mado (lattice windows) are windows with some kind of lattice. The traditional lattice is often a vertical one made of wooden slats, but modern versions can be horizontal or various kinds of grids.

Koushi-mado (photo: Paul McMahon)

Renji-mado are windows with vertical slats lined up in regular intervals, and also used to be known as musha-mado (warrior windows).

Renji-mado (photo: タケル)

These styles of windows originated in temple architecture, which was introduced to Japan from China in the Asuka period (538 to 710 CE). There, they had some spiritual significance, and the “renji-mado” originally meant “windows to confine spirits.”

From temples, they became more widely used in other buildings, such as castles and general residences, as a way of preventing intruders and maintaining privacy while still offering good ventilation.

You can still see these traditional styles of windows used in temples, shrines, castles, and tea houses, and occasionally for decorative purposes in more modern buildings.

Is an end to these window security bars in sight?

The prevalence of window bars has been on the decline, with an average of 2 windows per house having them in 2006–2010, 1.5 windows per house in 2011–2015, and 1.2 windows per house from 2016–2020. One reason may be a trend of using tall and narrow windows which reduce the risk of burglaries without using bars and are also more effective in sealing homes for better insulation.

But another reason may be that burglaries themselves are decreasing in Japan. Residential burglaries in Japan peaked in 2003 with 190,473 cases. They’ve been falling ever since, and in 2022, there were only 15,692 cases. With the risk of being burgled being so low, people may feel they’re no longer necessary.

More about the author

Photo of Paul McMahon

Paul McMahon

Founder of TokyoDev

Paul is a Canadian software developer who has been living in Japan since 2006. Since 2011 he’s been helping other developers start and grow their careers in Japan through TokyoDev.

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