Architecture: snow-safe roofs in Japan

 Why the houses of snow-buried Hokkaido gave up the pointed roof @YouTube

in a city where snow piles up metres deep, stand houses with the middle of the roof sunk into a V. These are Hokkaido's snowless-roof houses. 

And the hollow is not for looks: it is there on purpose, to hold the snow so that it never falls outside. Where snow is heavy, roofs are usually built as steep triangles so the snow slides straight to the ground. But then the heap under the eaves buries the ground-floor windows and the front door, and in dense neighbourhoods it crushes the neighbour's fence and can bury a person alive. 

Houses stand almost wall to wall, and dropping snow onto someone else's land is against the law. So why not lay heating cables and melt it all? In a minus-ten-degree wind the meltwater turns into giant icicles at the eaves, and the drainpipe freezes and bursts.

Shed it and the house is buried; melt it and it freezes and bursts. What the architects of the north used to overturn that dead end is in the video.