Lifting a building to add a floor - GIF

Lifting a building to add a floor.

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Previously:

Group wall lifting fail - GIF
Lifting a Lexus yacht out of the water - GIF
Lifting giant rocks in China - GIFs
Many Amish men lifting and moving a large barn by hand - GIF
Roof lifting posts - GIF

That scares me and I'm fearless...

At least that one guy looks skeptical.

Why not add a floor on top? That looks extremely risky, for both workers and building itself.