Why do so many Japanese buildings have external stairs?
November 7, 2017 9:43 PM   Subscribe

I’ve noticed that so many Japanese buildings have external staircases. But why? I strongly suspect that there is a policy reason for this, but I can’t prove it. This excellent album shows what I’m talking about.

External stairs seem really common in Japan, at least compared to North American cities. My best guess is that some planning law or building code incentivizes this (probably for emergency egress reasons). I really want to know whether that’s correct, and if so what the policy is. Is anyone aware of any authoritative writing on the subject (English or Japanese)?

My Japanese is passable, but sadly much too slow to go skimming through building codes myself.
posted by ripley_ to Grab Bag (6 answers total) 6 users marked this as a favorite
posted by Freedomboy at 10:45 PM on November 7, 2017 [3 favorites]

A possible reason is to save on heating costs- a stairwell is a large volume of little-used air to heat all winter. But earthquakes sounds good too.
posted by pseudostrabismus at 11:09 PM on November 7, 2017

The Japanese Wikipedia article on emergency stairs has a section on Japanese laws about the subject
posted by sacchan at 1:09 AM on November 8, 2017 [1 favorite]

Tall buildings require evacuation stairs, and really tall buildings require special evacuation stairs. Both have pretty specific requirements, here's the law about it. Maybe it's easier to meet these requirements with outside stairs, and/or special evacuation stairs need to be outside in the first place.
posted by sacchan at 1:20 AM on November 8, 2017 [2 favorites]

After some reading (very little, and I'm not a building code expert), it seems like the main reason for using external rather than internal emergency staircases is that external staircases have less onerous regulations.

For example, according to one website I looked at (Japanese-only), internal emergency-use staircases must be enclosed, with small windows, battery-powered lighting, signage, nothing that could form a hindrance (which means nothing can be placed in the stairwell or it can no longer serve as an emergency egress), all things taking up the pennies that developers would prefer to pinch.

Probably more importantly, internal stairwells take up a lot of space that developers are very keen to maximize, especially for smaller residential buildings.

Most people on Chiebukuro seem to agree that the main motivation for external stairs is the ease of implementation and the fact that they free up more space internally, since any internal staircases don't necessarily need to meet all the requirements of an emergency egress.
posted by wakannai at 1:34 AM on November 8, 2017 [7 favorites]

You can also see plenty of external stairs like that on public buildings in CA. The campus of UC Davis has several, I assumed for a mix of saving money and more easily meeting safety standards, much like what is described above.
posted by SaltySalticid at 5:33 AM on November 8, 2017

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