From Carl Hagstrom, Systems Administrator at WOODWEB
Stairs come in hundreds of different styles, and the construction methods vary significantly. For each method, taking care of the final details typically requires approaches that are unique to the style of stair.
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 than the tread depth:
Then I carefully drill a pilot hole slightly smaller than 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.
We're never too old to learn, and I hope what I've posted above puts one more tool in your toolbox.
Forum Responses
(Architectural Woodworking Forum)
From Contributor O:
Thanks for posting that Carl. I love the fact that the complex is made simple with a sharpened brad and a stick. I have made plenty of stairs, but never had to do a skirt like that and wondered how it was done. Apparently the method has the additional benefit of being timeless - a trait I am unable to claim.
I'm not sure I agree with the "never" part, and I doubt Don Zepp would either. He ran a production stair company before becoming an instructor at the school, and I remember him saying his company installed over 10,000 sets of stairs. I emphasize the "production" aspect of his experience. There's little doubt in my mind that the scribe technique was intentional, and part of the plan, not a fix-it strategy. And I'd also wager that his approach was in place because it was the fastest and least expensive way to install a set of good quality stairs that were acceptable for the development type houses he worked on, which reminds me of a story he told.
He wasn't long out of trade school (he attended Williamson as well), and had started his stair business, and hired an old German stair guy named John. First day on the job in the development, he gave John instructions to take care of the railings on house 28 (I'm making up the numbers, and guessing at the time frames mentioned below), and then do the railings on number 32. Don said that it typically took him four to six hours to install the railing on this style house, and as he was finishing up the first house he started on, John came in, sat down, opened his lunch pail, and starting eating a snack. Don asked him if he was done the first house, and John said yes. So he said to go on to the next house, and do that railing. John said he had done that one too. Then Don said to me "I wasn't the smartest person around at that time, but I was smart enough to know to leave him alone."
He also talked about how it took years before John started showing him the tricks he knew. Don said at that time, production stair folks made real good money compared to the other carpenters, and they didn't divulge tips readily. He also said if John was working, and someone would come up and start watching, he'd go grab a snack and start back up when they left. Finally, Don said when John got really old, they'd carry all his tools in for him, and help him up to the different levels where the work needed done. Again, Don worked almost solely in a production environment. Maybe the stairs were far below "custom standard", but there is elegance to efficiency that to this day I still enjoy admiring in all the trades.
There are basically two kinds of "production work". The first involves shop or factory units and the second are job-site built stairs. These are really apples and oranges and probably the source of any differences of opinion we may have. A finished stair built in the field, usually involves complete or partial over-layment of a rough stair. This is where we might expect to scribe skirt or otherwise jump through carpentry hoops. Scribing and cutting skirtboard though, is at best, a finicky and frightening operation for any finish carpenter (hence your great TIC article).
Scribing skirt is generally not part of any factory production process and that's were real production takes place. In the production planning, no one would plan to do something difficult or time consuming. No site-built units can honestly compete with finished factory stairs. It seems the only reasons we continue to built job-site stairs at all is that in most cases, a functioning stair is required to pass first-floor framing inspection. The framed stair is also part of approved plans and built by licensed contractors, whereas purchased (out-of-state) units raise questions. Therefore rough, local carpenters continue to bash boards together (to the everlasting and expletive frustrations of finish carpenters). Well enough of that.
As for the actual production methods of scribing and cutting skirt board along the wall, the first thing is to notch the nosing and any cove moldings off the tread entirely and to the face of the riser. (There's no way I'm going to take time to meticulously cope the skirt around all of this). This is typically accomplished with a reversible trim saw held firmly against the upper skirt board or scrap. With a few careful strokes and chisel cut, the nosing is off. After that the scribing is just a straight-edge set against the face of the riser and a line drawn parallel from the top of the tread with a scrap of wood. Any minor gap between the cut notch and skirt is shimmed tight. The skirt cutting is then all straight forward without coping around any nosing details. The method also accommodates the occasional treads which are skewed or angled from the wall. I do believe Mr. Zepp would agree with all of this although he undoubtedly would still do it his own way (like you and me). Anyway this is one of my old "stair secrets."
This made portability somewhat difficult and is the reason a seasoned a stair man from company A could make the move to company B and be considered a genius (as in Carl's tale of the old German guy), or an idiot, doing everything wrong and using crazy methods no one had seen before. Add in the cultural heritage differences (old German guy) and those variations grow even wider. For the solo guy out in the field, tasked with who knows what, these variations would be even broader, as he worked alone and never had anyone to show him this technique or that method. While we witness a varied range of opinions in the trades today, just think of those lunch time discussions way back when, where Nationalism, heritage, training, experience and who knows what else all played a part in determining what was considered better or superior, and no resolution ever in sight.
As long as the MC of the material is appropriate, skirts scribed in this manner do not "leave huge gaps between the perfectly scribed stringers and the risers/treads". I'll include what I mentioned earlier: "It's also worth noting that when you fasten the skirtboard, keep the fasteners nearer to the inboard edge, and away from the outboard edge. That will help mitigate any seasonal shrinkage/expansion of the skirt by greasing the outboard end and allowing it to move while the inboard side is fastened." For sure, to each his own. My take is a scribed skirt (vs. cut and butt) turns the line of sight 90 degrees, and is way more visually forgiving of any movement at the wall stair carriage interface.
