We got call from a gentleman regarding a 1980 ish stair that had half walls down to the floor. He wanted a more formal layout with exposed treads and hand rails.
We do not do demo anymore because of lead based paint and asbestos rules. Not that we are against rules and safety, The liability aspects just don’t appeal to me. With that, the home owner took that part of the project. We had somewhat of a clean slate when we arrived.
The scope of the rebuild was to replace all the treads and risers. The treads were red oak. The risers were poplar that we painted white. The treads on the exposed sides had mitered returns on the treads and risers. We cut a new side boards on the inside walls at the top of the stairs because the side stringers were beat up. The handrail is continuous on one side per code. The other side was ended at the wall. Continuous handrails are required on one side on this stair width.
We removed the treads and risers from the old set. We cut the riser boards 45 deg on the ends to return against the the new skirt board. I set the placement of the 3/4 inch skirt board against the studs so the skirt would be 1/4 proud of the 1/2 Sheetrock. The risers were set with a laser . You could also use string or a straight edge, after all the risers were set,we set the skirt board against them and scribed all the plumb and level cuts.
I cut my own miter returns. It can be somewhat intimidating to younger carpenters. If you can cut a straight line with the Skil saw then you can do this.I do the 45s on the ends first. I clamp them together edgeways on the bench. With the skill saw blade cut it at 45° angle. You will be adding a 1 1/4 inch bullnose to the side edges. You need to set the depth of cut to account for the 1 1/4. With them all clamped to together you have a base to to support the skill saw. If you have less than four treads it is easier to cut the miter with a very sharp hand saw. The next cut is the long crosscut to intersect the back of the angle cut on the front. I use a skill saw then finish the last part with my hand saw. Just be careful and take your time. Keep your saws square to the work. I leave the short return off until I am installing the cove under the treads.