I have an old cape cod "montgomery ward kit house" erected in 1946. The stairs are EXTREMELY STEEP and narrow. Run is 7 1/2" and rise is 7". How easy of a job to remove existing treads/stringers and install new with stringer/treads to make stairs safer?
I'd like to do this now before I button up the basement which currently exposes the stairs to the second floor as well as basement.
The toughest part is getting the layout right. Current code requires a 10" minimum run, measured horizontally from the nose (not the riser) of one tread to the plane of the nose below. When going from really old 7-1/2" runs, the location of the bottom landing is going to change 2-1/2" for every tread you have. That is a lot, especially if you have 10 or 12 treads.
Another thing to really consider is headroom. Moving the plane of the stairs outward will greatly reduce headroom if there are any obstructions over the stairs.
My only suggestion is DRAW A PICTURE. A section view of the stairs perpindicular to the risers will allow you to do the math, and verify that you're cutting it right. Never rely only on a calculator to do it...Double check the math against the home's dimensions.