A finished skirt board on a flight of stairs is one of those tasks in finish carpentry that remains in prominent view, always open to critique. It’s critical that the workmanship is of the highest caliber.
Scribing the skirt board
To scribe skirt board over installed risers and treads, start with a straight skirt board laid on top of the points of the treads with the bottom corner against the finish or sub-floor, and the top corner above and beyond the top tread nosing. Finish nail this piece to the wall (leave the nail heads and part of the nail shank exposed for easy removal) and mark two registration lines on the wall, on the top of the skirt—one above the bottom tread and one above the top tread.
Using an oak stick for a scriber (with a slightly rounded bottom, so it contacts the treads and risers like the point of a standard scriber)…
…mark the height of the rise, or slightly more (use the highest riser if there’s a variance) and put a sharpened nail or brad through the stick with the point protruding slightly.
Next, scribe the level line of each tread (it’s important that you hold the scribe stick plumb), starting at the bottom and finishing at the upper landing tread.
Now, take the skirt board off the wall, cut the bottom scribe mark, and slide the skirt board down the wall until it rests on the floor. Make sure the top of the skirt is lined up with the registration marks you put on the wall. Finish nail the skirt to the wall again, leaving the nails proud for easy removal.
Next, change the brad point from the riser to the unit run dimension (or a little more).
Scribe from each riser face moving up the stair from the bottom. Again, it’s important to hold the scriber level as you work your way up the flight.
While using the same scribe setup, mark the projection of each stair nosing.
Next, remove the skirt from the wall and, using a sample tread block and a sharp pencil, draw the nosing, using the slight arc you previously scribed from the tip of the nosing as your reference point.
It’s time to start cutting. Start on the first riser line and cut every riser on the plumb line, working up the flight. Next, cut the treads on the level lines, starting at the top and working your way down. Remove the triangular piece as you go. Use a coping saw or jig saw to cut out the nosings.
TIP: When cutting, hold the saw at a slight angle to achieve an undercut, except for the top and bottom plumb cuts that the base will die into.
Once you’re finished cutting out for the treads and risers, slide the skirt into place and check for the “$20 fit” (a $1 bill will do, in a pinch). I like to have just enough material left above the nosing to allow some flexibility in the skirt, and also enough to receive a carpeted edge, if it’s not a finish set of stairs. Usually 1 1/4 to 1 1/2 in. is good. Depending on the rise/run and size of the original board, you may have to rip some material off the top edge.
Next, use a level to mark a plumb line on the skirt board at the top and bottom that matches the height of the flat portion of your baseboard. These lines will mark the vertical cuts for the skirt-to-baseboard transitions.
After cutting the base transitions, it’s time to nail the skirt in place. Nailing through the skirt at the nosing will draw it up tight. I also pre-drill each section of the skirt where it fits against the tread, close to the riser, and install a 4d finish nail.
Finish up by adding the base, base cap, and cove moldings. You’re done!
One advantage that I’ve found in scribing the skirt over the treads and risers is that the joint between the skirt and the finish stairs is not staring you in the face as you walk up the steps. It’s the same principle as starting the base or crown at the far end of the room and fitting to it.
The installation time is reduced with this method, since only the skirt board will need to be cut accurately. The time-consuming process of scribing and fitting each individual tread and riser is eliminated.
If it’s your first time, it might be a good idea to start with a set that will get carpeted, or with a painted skirt. It will give you the opportunity to practice before you try this method on a stained skirt board. Once you get the hang of it, you’ll get quick and accurate.
It’s not the perfect method for every installation, but for some jobs, it’s efficient and workmanlike!
(This TiC Toolbox article was adapted from Scribing Skirt Boards; Drawings by Wm. Todd Murdock)