Skirt Boards Traditionally, a straight run of stairs gets a skirt board on both sides. The wall skirt runs on the same plane as the flooring baseboard and gets finished out with the same base cap. On the open side, the face skirt acts as an apron running below the treads, and also gets finished out with base — except here the cap is run upside down. Wall skirt. I’ve seen old-timers scribe and notch the wall skirt around each tread. I’ve tried it once or twice, and it’s come out okay. But it’s tricky, and if it doesn’t come out right the first time, you can end up chasing an elusive good fit forever when you try to tune it up. I don’t think it’s worth it. Instead, I always leave a gap between my rough stair and the wall by installing a 2x4 between the bottom edge of my first rough stringer and the wall studs. This leaves room for the drywall to be slipped down first, followed by a 1x10 wall skirt. To mark the cuts for the wall skirt, I temporarily tack the uncut board along the corners of the rough treads (Figure 4).

Figure 4: To notch the wall skirt around the landing framing, the author tacks the wall skirt along the nosings of the rough treads and marks a level line one standard rise above the landing floor.

I then set a compass to the distance of one rise and scribe level cuts at the main floor and the landing floor. This scribe technique allows the cut wall skirt to slide down flush to the floor so that its bottom edge will be hidden behind the finish treads and risers. I use a level to mark a plumb cut line at the top where the skirt hits the landing. This plumb cut line intersects the landing level cut line and together they mark a notch that fits around the landing where it’s attached to the wall (the landing is not spaced away from the wall the way the stringers are). If you’re tying into baseboard that is thinner than 3/4 inch, I recommend you plumb-cut the wall skirt at the top and bottom to simply catch the baseboard. But, if you’re using two-piece or 3/4-inch baseboard, you’ll want your baseboard to continue down the stairs as your wall skirt. Decide on the height of the baseboard first, then set the skirt board so the top edges will meet in a smooth transition. Instead of making a plumb joint, which exposes end grain on the skirt board, I prefer to make a miter cut. If you know the theoretical angle, you can simply halve it. If not, you can use a simple compass technique to manually bisect the angle ().

Face skirt.

The face skirt has level cuts at all tread overhangs and vertical miter cuts that will tie into the risers (Figure 6).

Figure 6: To scribe the face skirt, the author uses a level to mark true plumb and level cuts for each sub-riser and sub-tread.

When installing the face skirt, I nail only along the bottom edge, so the top is "flapping in the wind." That way, later on, I can move the top of the board to align it with the miters on the risers. Don’t forget to glue the ends of the face skirt to the newel posts. To cut the face skirt to length, first make a plumb cut where the skirt meets the bottom newel. I usually cut this to the theoretical plumb cut for the stair — 36.9 degrees in this case. Then, I hold it in place and mark the top plumb cut where it meets the landing newel. At this point, I can’t assume that my newel posts are perfectly parallel, so I cut the skirt slightly long, then scribe it to fit with a sharp block plane. After fitting the face skirt to length, I tack it over the ends of the rough stair, holding it a little high to allow for the top corners of the finish risers, which are going to be 3/4 inch proud of the rough riser. I then use a level to mark the cuts for each rise and run. Because the framing may be slightly out of square, I center the bubble for each line I mark. Then I pull the board off, and using the same level, I transfer the lines back where the cut needs to be made. These lines are on the inside of the skirt board. The plumb cuts, which will miter into the risers, will be cut on a 45-degree bevel, and the horizontal cuts will be square. I start by cutting the miters. This is a right-hand stair (when you look up the stair, the handrail is on the right-hand side), so I can cut the miters with a circular saw, which usually has the blade set to the right. On a left-hand stair, I would need to use a saw with the blade set on the left side, like most worm drives. Cutting from the backside of the face skirt, where the marks are, you can overcut the miters a little in the corners, because the kerf won’t show through on the face. This makes it possible to remove the triangles entirely when making the level cuts.