Bolt Stair (Structural-Bolt Staircase)
Apparently floating staircase with bolted treads.
In a bolt stair (structural-bolt staircase) the treads are connected to each other and to the wall via bolts. There are versions with an external stringer and stringerless variants where the treads are connected solely through vertical or horizontal bolts and to the wall. The handrail with posts and spindles assumes a structural role. Bolt stairs appear light and modern, allowing light to pass through the open construction.