Changing Stair Rise After Landing Replacement
A landing is required if the door swings outward, except for screen doors. The landing is to be the width of the door and a minimum of 36” in the direction of travel. (See ICC R311.4.3.)
The maximum rise of steps is 8”. The maximum difference between risers is 3/8” from smallest to largest. (See ICC R311.5.3.1)
The minimum tread depth is 9”. The greatest difference from smallest to largest is 3/8”. (See ICC R311.5.3.2)
A handrail is required if there are 4 or more risers. The handrail is to be installed a minimum of 34” and not to exceed 38” (See ICC R311.5.6)
Handrails are required on one side only. (See ICC 1009.15) It’s customary to have it on the right side descending, but not mandatory.
Handrails are not required if there are 3 risers or less. (See ICC 1009.15.4)
Make sure you have a minimum of 1 1/2” clearance between the handrail and wall. (See ICC 1012.7)
I think you’ll have to remove the treads and adjust the height of each so no tread is more or less than 3/8” compared to the height of any other riser.