There shall be a floor or landing at the top and bottom of each stairway.
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Exception: A floor or landing is not required at the top of an interior flight of stairs, including stairs in an enclosed garage, provided a door does not swing over the stairs.
- A flight of stairs shall not have a vertical rise larger than 12 feet (3658 mm) between floor levels or landings.
- The width of each landing shall not be less than the width of the stairway served. Every landing shall have a minimum dimension of 36 inches (914 mm) measured in the direction of travel.
My interpretation, which seems to also be that of West Coast Jerry, is that the landing must be in the direction of travel, straight down the stairs, i.e., the direction in which one would most likely fall.
HOWEVER, ...
Many, many, many, many (did I say "many"?) building officials and inspector say that winders ARE allowed 'within' a straight flight of stairs.
Those same building officials and inspectors (may I say "many") also treat "the direction of travel" as being a radius from the top corner of the first riser ascending or the last riser ascending. I.e., you can have a straight flight of stairs, a semi-circular landing, then another straight flight of stairs.
*I* say you need a straight landing, THEN you can make the semi-circular landing turning to the next flight of stairs.
*Some* building officials, inspectors, architects, etc., agree with that, many, many, many more do not.
When calling that out, check with your AHJ and see what they allow, and if they are one of the ones who allow those trip and fall hazards ... try to get them to change their mind (it is extremely difficult to get them to change their mind).
Besides, if you refer to the book which many HIs provide for a Visual Interpretation of the IRC, you will find ... winders shown in a otherwise straight flight of stairs, with winders taking the place of a proper (in my opinion) landing.