“stairs” part 3: the big finish
Finishing the stairs starts with skirt boards. These are the trim pieces that run down each side of the stairs and to which the treads and risers abut. There are books with lots of fancy calculations for determining dimensions, which I used, but when I swung the ungainly pieces into place, they just didn’t fit exactly right. So I went back and forth to the saw a few times to trim them to fit. I then tacked them through the drywall into the studs, which I had marked earlier.

Skirt boards running down each side of the rough stairwell.
Ok, just so you don’t think I was Johnny-on-the-spot finishing things up, several months would pass before I got around to the treads and risers. The thing about finish work is, it’s what you see, so you have to think about how you want it to look. And that can take some time.
I knew I wanted oak treads. In fact, I had purchased the treads a few years back at Home Depot, when I saw them in an end-cap display, not realizing they always carry them in the aisles. They’re 1″ thick (well, really they’re 31/32″- and that makes a difference when you have eleven steps, because if you don’t account for it, you’ll be off almost 1/2″ from top to bottom), and they’re solid oak, but there’s a core of glued up oak pieces veneered with a 1/8″ oak finish. The bullnose is already cut. So I’ve had them forever, and they’ve always been in the way as I worked on other stuff, and I’ve probably moved them around the job site fifteen times, including moving them upstairs and back down again. They’re heavy.
But the risers were a different matter. White painted risers with oak treads is common, and I don’t dislike the look, so I considered it for a time. It would have been a little cheaper, because you can use a less expensive wood like poplar. At one point, I committed to that idea once and bought the poplar, but then had second thoughts and returned it. The white riser has a colonial-ish look to it, which I didn’t want. And, I guess I’m a sucker for oak.
So I went back to Home Depot and picked through the stacks of nice 1″x10″x12′ (really 3/4″ x 9 1/2″ x 12′ – remember dimensional lumber?) oak boards and found a few that were knot-free and took them home and ripped them down on the table saw.
WARNING: The following paragraph contains content that may haunt your dreams. Read at your own peril. And, of course, parental discretion is strongly advised.
One of challenges with building stairs in place (as opposed to building the unit and then setting it into place, which gives you a nice fit but wasn’t an option due to my narrow and access-restricted stairwell), something that caused great anxiety in the lead-up to tread & riser work, is… oh, I just can’t bring myself to say it yet. Let’s say, for instance, that you cut a tread and it fits snugly into place. Then you cut a riser, but it’s a tad wide. Why would it be wide? Well, the skirt board isn’t a perfect surface, and it’s attached to drywall and framing that carry their own irregularities. So things are always a little out of whack. You tap the riser into place. And it fits snugly. Maybe too snugly. Then you look at the tread you just put in and there are… gaps on the sides. Yes, I said it. Gaps. Egde gaps. Because the riser you just tapped into place shoved the skirt board out, ever so slightly. And you think, maybe I can just trim the riser a bit. But you know you only need to trim a little bit. And you wonder whether you’re good enough with the table saw to take just enough. Or should you try a block plane? Or maybe a rasp? And if you take off too much, then the tread will be fine, but the riser will have edge gaps, and you’ll have to throw it out and start over. And then you look down the long stairwell and realize the nightmare will continue, step after step, down into oblivion.
So what do you do? You read some books. And you come up with some tricks. They make special adjustable template tools that allow you to easily gauge the shape of each piece. But a little trick I learned, with two long pieces of paper and some tape, did the same thing:

Using template, but still getting Edge Gaps.
Just slide the left piece of paper against the left skirt board, and the right piece of paper against the right skirt board, then tape them together. Carry that to the lumber, trace your shape, and cut.
So did it work? Well, not really. The books, which are aimed at real finish carpenters, who have the skill, patience, and tools, tell you to use a block plane or rasp to get the right fit. I don’t have any of those, so I just got it as close as I could. Look again at the picture above. The riser just above the paper template. And the one above that. See the right-hand edge? You guessed it. Edge gaps.
I cut all the risers first. It allowed me to assembly-line things, and I could make sure I got them perfectly even with the tops of the rough treads. That way, where the treads meet the risers would be a tight fit.

Risers first.
The more I moved downwards, the less I worried about edge gaps. I decided that they were minor, and I could probably fill with something, maybe some white caulk, which would look fine since I planned to paint the skirt boards white. Caulk fixes everything.

Almost down.
At this points, it’s just a dry fit. I wanted to make sure I had everything fitting before I started connecting things together.

The dry fit - except the top threshold.
If you look closely in the above picture, you’ll notice that the top threshold is not in place. It was a tricky piece, because it had to dovetail around and under the doorjamb, and also dovetail with the first floor’s existing 55 year old oak flooring. If the following picture, you can see the edge of the first floor, and you can make out the tongue that runs along the edge – that would need to fit into a groove in the threshold piece.

edge of old upstairs floor
I took a spare tread and cut it down to the proper width, then ripped a groove in the edge on the table saw. I then cut the left and right ends to the correct pattern to fit with the doorjambs. I also had to cut a little away on one edge of the underside, since the rough wood beneath wasn’t flat. The result is pictured below:

Old meets new.
Attaching the treads and risers was easy, with no hardware showing, because I had access in a small storage area underneath the stairway. For each piece, I used a generous bead of construction adhesive to stick it in place (and prevent squeaks in the future), stacked a few boxes of ceramic floor tiles on it to hold it, went underneath and drilled holes, then screwed it in place. Six screws each. The bottom tread and riser were tricky because of lack of space, but a right-angle attachment for my drill aided in getting the screws in. The top riser had no access from below, so used a few finish nails to attach it. And, the top threshold also had no access from below, so I drilled and countersunk (sank?) five holes through it to affix it, then used oak plugs to hide the holes. In the picture above, you can see one of the plugs slightly to the right of the picture’s center.
I trimmed the skirt boards with a bit of cove molding cut from the top of a piece of the baseboard that I was using throughout the basement. The result is a cap on the skirt board that matches the rest of the baseboard.

The cap detail on the skirt board matches the cap detail on the baseboard
I also ran a 1″x4″ trim piece around the perimeter of the stairwell, seen in the following photo, to hide an overlapping piece of drywall on the right side. The edges of the new drywall in the basement and the old wallboard in the upper part of the stairwell butted perfectly on the left and far sides. But the way framing worked out, with the immovable steel I-beam running down the center of the house, the edge of the new drywall on the right didn’t butt evenly with the edge of the upper wallboard – it stood out about 1/2″. So I capped it with the 1″x4″, (actually 3/4″x3 1/2″) and continued the 1″x4″ around the stairwell as a deign element.

Whatever you do, don't look down.
In finished the stairs with three coats of semi-gloss polyurethane, letting it dry for a day then lightly sanding between each coat. All the trim is white semi-gloss acrylic, and the drywall below the 1″x4″ perimeter piece is the light gray that the rest of the walls in the basement are painted.

Three coats of polyurethane.

The view from above.

The "Monument" view.
In order to pass final inspection, I’ll have to add a handrail. It’s a shame. It looks so nice the way it is.