
When is a door not a door?
A few years ago a fairly strong earthquake rocked the area I lived in. Luckily, damage was relatively limited, but it certainly was an intense few minutes. During that moment, while I was rounding up the kids into a safe part of the room, I was surprised to see that the first thing my wife did was immediately rush towards the front door and open it.
Not being nearly as experienced in earthquakes I had no idea why at the time, but after she explained that strong tremors have a tendency to warp the frames of doors, making them impossible to open and trapping the people inside. That could be a worst case scenario, but even if people were swift enough on the uptake to open their door during a quake, the warping might still leave it impossible to close and lock properly, causing a whole other set of security issues.
It’s a big problem, but one that Shin Nihon Entrance in Tokyo has developed an elegant solution for. Tasukaru Door (“Lifesaver Door”) is quite simply a door within a door.
To put it less simply, the door within a door is actually a taishin door (seismic door) which has features to make it less likely to become jammed when deformation occurs. If you look closely at the pictures and video, the inner door has more space between the edges and its frame. This means that in the event that the door bends, the frame is less likely to make contact with the edge of the door and prevent it from moving. The extra clearance between the inner door and its frame is then covered by a flat lip that runs along all sides on the outer and inner surfaces.
▼ That might be a little hard to visualize, so here’s a rough diagram

In addition, what’s the point of having an emergency escape door if you can’t enjoy it every once in a while too? That’s why Tasukaru Door has the added benefit of safely opening with a screen cover to let some fresh air in and rescue us from not only earthquake damage, but the sweltering summer heat.
▼ This could be you!

It’s a pretty solid idea all around, and as a result Shin Nihon Entrance has been receiving requests for Tasukaru Door to be installed in 290 condominiums in Saitama Prefecture alone since it was first released in February of 2021. So, everyone in condos and apartments should keep their eyes out for these double-door designs, because they may become the norm before too long, and help save a lot of lives in the process.
Source: Shin Nihon Entrance, PR Times
Top image: PR Times
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