I am designing a set of spiral stairs for the brownstone green show house in Brooklyn. I want it to be as close to the corner where the wood meets the metal walkway so that it takes up as little as possible of the opening.

The head room is much better if the stairs spin under the metal walkway. But my main concern is that the stairs are as tight in the corner as possible so that they don’t take up space in the opening. What is the best way? The normal way is to make a landing but this eats into the space and it makes no sense to make a landing since the metal floor itself is a landing since it is so thin at 4″ (i.e. lots of head room going down.)

The distance from the floor to below the metal is 9’2″. The metal is 4″ so the distance from floor to floor is 9’6″.