Depending on the circumstances, there are times when a stair builder needs to carefully fit treads and risers between to fixed skirt-boards. I've seen installers fuss, fight, and fidget, carefully cutting treads and risers so they fit really really tight to the skirt board(s).

But few installers consider installing the treads and risers first, and then scribing the skirt-board to the finished set of stairs. And who could blame them ... after all, it'd be foolish to think that you could make so many intricate cuts and expect to end up with a flawless fit.

The truth is that scribing a skirt-board is really quite simple,and it can be done without ever touching a tape measure ... really.

The photos and descriptions that follow are based on a stair skirt I scribed about 20 years ago. The process is pretty straightforward, and the captions associated with the photos pretty much tell the story. I've included additional comments and observations at the end of the article.

And a big thanks goes out to Gary Katz - the photos I took 20 years ago were in slide format, and pretty beat up. Gary went through them, and did a beautiful job cleaning them up ... his efforts resulted in some nice, clean images.

I start by tacking the rough skirt board on top of the treads:

You'll notice that the lower edge of the skirt doesn't touch the edge of each tread:

It's been my observation that no matter how fussy you are with the riser/tread layout and installation, there will always be some minor discrepancies along the flight. That's why this scribing technique works so well - it accommodates any irregularities found in the final positioning of the treads and risers.

I start the scribing process by transferring the top height of the tread onto a 3/8 X 3/4 oak scribe stick that's a couple of inches longer the the tread depth:

Then I carefully drill a pilot hole slightly smaller then the diameter of the brad, and drive a brad through the stick. I like to sharpen the brad point for a near razor like scribe line:

Then I scribe the level lines onto the skirt board, starting on the finish floor, and working my way up the flight of stairs. It's important to keep the stick plumb, and I typically make one light pass to "set" the initial line, and then follow up with a couple more passes to really engrave the line in the skirt board:

Making a thin deep scribe line goes a long way towards preventing tear out when you start making the cuts. I darkened the scribes lines using a pencil to make them more visible in the photos.

It's important to note that in the photos above, the line that extends from the top of the tread onto the skirt board is referencing the tread below the line. The scribe line has no relationship to the tread it extends from. The scribe line I'm working on is referencing the finish floor (not the first tread).

After I've marked all the level (tread) scribe lines, I mark a reference line along the top edge of the skirt so I can reposition the skirt accurately when it's time to scribe the risers:

After pulling the skirt off the wall, I cut the bottom of the skirt at the lowest scribe line:

And tack it back up on the wall, using the reference line to position the skirt at the original angle.

Next, I remove the brad from my scribe stick, and transfer the nosing length of the tread onto the scribe stick:

Then drill another pilot hole at the mark, drive the brad through the stick at the new location, and start scribing the nosing edge:

And then the riser faces onto the skirt board:

After I've scribed the risers and nosings, I pull the skirt off the wall, set it on horses, and using a scrap piece of tread material, connect the dots between the riser, nosing, and tread for the entire flight of stairs:

When all the steps are marked out, I break out the saw, and carefully cut just to the scribe lines:

When the scribe lines are cut sharp and deep, and you're careful not to cross the scribe line with the saw, there's virtually no tear-out. I use a slight back-cut angle of about 4 to 5 degrees - this helps ensure a really tight fit when the skirt is driven into place. While the skirt is on the horses, I also cut the ends to match the baseboard at top and bottom.

I set the skirt in place a few inches shy of its final position and slide the skirt as far as I can into final position to confirm all looks right.

When I'm satisfied that it's a good fit, I use a block to drive the skirt home:

For the final fit:

I was fortunate to attend Williamson Trade School (a three year post-high school program) when Don Zepp was the carpentry instructor. He was flat out the best instructor I've ever been fortunate enough to have learned from. His background was in production stairs (and he was a wizard when it came to stairs), but he knew more about carpentry then any individual I've ever met.

Don also taught me how to use a framing square, and I still have my notebook that explains how to cut hips, valleys, and cripple jacks for unequally pitched hip roofs.

Don passed away a few years ago, but there are hundreds of carpenters out there who not only learned from him, but hold him in the same esteem that I do.

"This Is Carpentry" (Gary Katz's site) published a very similar article by Norm Yeager, who also attended Williamson. That article inspired me to dig out the old photos above ... you can view Norm's take on the process at:

Scribing Skirt Boards

We're never too old to learn, and I hope what I've posted above puts one more tool in your toolbox.

Carl Hagstrom
Systems Administrator at WOODWEB