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I’m after my first set of winders. The detail originally showed a landing for a short third side, but the three steps to the landing created a head height issue, in the center of the landing. This landing was 4’7″ wide. Layout for a normal switchback staircase put the upper landing nosing right under the door to the stairwell from above. I established the upper landing nosing as per UBC, off the future bearing hallway wall on the floor above. From this point, I set the center wall to create the shortest code clearance possible from end of the center wall to the short leg of the U. (width of the stairs). I am trying to get enough winders in to pull the nosing of the first step at the bottom inside of the center wall.

The stairs are 3′ wide. A 36″ upper landing, and 36″ clr. around the end of the center wall. I laid out five winder sections, which left my bottom nosing 2″ in from end of wall. All seems fine, except the code as written has me somewhat confused. Shortest section of the winder no less than 6″. At a point 12″ out from short end of winder, tread depth no less than 10″. Ok, but this must mean that the tread depth rule at 12″ supercedes the 6″ min width at the narrowest, as you wind around the end of the wall. A circular set of stairs would have very narrow sections at the post the turn on, but would still conform to the minimum going rule at 12″

Any reason this principle cannot apply to a 3 1/2″ wall as well, with quite narrow going at the narrowest point?

If a winder could be wrapped around an ideal width of center wall, for asthetics and finish, what would the width of that wall be? I laid it out for a 2×8 wall, and a nosing took off from each corner, one in the center of the handrail wall, and on each side conforming to the 6″ rule of run to the next nosing. Any better than a tighter turn with smaller short sections?

Last, this problem is somehow related to 180 degrees of a circle. Is this divided in the layout of the winders?

Ok, more. There is a piece of mechanical that is 44″ off the slab, in the right corner as you go up the stairs and turning left. What is the approach to frame? Framing for winders that stacks on one base landing, like a normal mid-span landing seems like a waste of useable access space to the sump. Headers with a 1’kick that are set into the end of the center wall, and pocket into the exterior sounds like a puzzler, but opens up the space below as much as possible.

Will buy