Staircase Reinforcement

March 3rd, 2025 - The stairs from first floor to second floor need to be repaired. The treads and risers creak, bow, and some are cracked. I began careful demolition last weekend, removing all the drywall from below the stairs. The plain 2x4s in the photo are not part of the stairs; the drywall was affixed to them. Initial plan is to remove the drywall framing, then add one or two stringers. A 2x12 stringer would be strong enough, and I think it is what building code requires, but it would be lower than the drywall ceiling I took out. A 2x10 might be the perfect fit, but after all the needed cuts, it might not be strong enough. Steel stringer? Build a rectangular brace (rough design pictured)? Use 2x12(s) anyway and replace basement stairs with slide or spiral staircase?