A comprehensive educational community devoted to trim carpentry, finish carpentry and architectural millwork. Hosted by nationally recognized author and finish carpentry specialist Gary M. Katz.
  Wainscoting Layout  
I used to scratch my head a lot whenever I laid out wainscoting panels. I’d figure out the panel size and start measuring across the wall, but I’d always end up off by an inch or more, so I’d start over and circle the new marks, so I wouldn’t confuse them with the old ones. I’d get a little closer on the second try but still be off by a 1/2 inch or more. The third time I’d get even closer. The fourth time…you get the picture? On long walls, I’d end up with marks inside circles, stars, squares, octagons, pentagrams--everything imaginable. Sometimes I’d have to spray the wall out with fast-drying white primer and start over. But I don’t scratch my head anymore over wainscoting layout because I now use a calculator.

Simplify the Math

To calculate the layout of the panel spacing, always begin with an estimate of the panel size--that’s the easiest way to determine the number of panels. Once the number of panels has been determined, the exact size of each panel is easy to figure out. But remember one important rule: There is always one more stile than there are panels—if there are seven panels, then there must be eight stiles (unless the wall you’re working on never meets another corner).

The wall in the above illustration measures 96 in. [Figure A], so the first thing to do is subtract that extra stile--3 in.

{96"-3"= 93"}

For this example, we’ll plan on panels that are 10 in. wide, with 3-in.-wide stiles. So divide the length of the wall by 13 in. (that’s the combined width of the panel AND the stile--the math is a lot easier if you combine the two measurements into a single unit). The result is 7 1/8.

{93"*13"= 7.15}

But you can’t use that number because it’s uneven--you must have an even number of panels. So round that result up or down to get an even number. In this case, it’s a lot closer to 7 panels than it is to 8.

Now you’re ready to get the EXACT size of the panels. Divide the length of the room (minus the last stile) once more, this time by 7--the number of panels. The result is 13 5/16. Since the stiles are 3 in. wide, that means the panel width is exactly 10 5/16 in.

{96"-3"= 93"}{93"*7= 13 5/16"- 3"= 10 5/16"}

To locate the beginning of each stile/panel unit, you could just add that dimension (10 5/16 in.) to itself as you measure across the wall, but notice what happens if you do (See Figure A). The last mark comes out pretty close to 3 in. away from the wall--almost enough room for a full stile, but it’s not PERFECT.

{13 5/16" + 13 5/16"( x7)......= 93" 3/16}

Using a Construction Master Pro Calculator

Pretty Close isn’t good enough for many of the jobs I work on, and besides, if I’m using a calculator, the layout should be precise, after all, the reason I invest in new tools is to speed productivity and ensure accuracy.

The steps for using a Construction Master Pro Calculator are exactly the same BUT, once you’ve divided the length of the wall by the number of panels and the result shows in the LED display (93 / 7= 13 5/16 in.) STOP!!

With the result--13 5/16--still showing on the display, simply press the “+” button and then the “=” button. But STOP THERE! The second layout position is now in the LED display. Notice the difference? The position is 26 9/16 in., NOT 26 5/8 in.!

The reason for the difference is simple: The calculator REMEMBERS and adds the exact amount of the result (93/7= 13.28), not the rounded number that appears on the calculator screen (13 9/16).


Just press the “=” button again and that exact quotient will be used to arrive at the PRECISE location of each succeeding stile—and the differences are dramatic for any caring carpenter: 39 7/8 in.; 53 1/8 in; 66 7/16 in.; 79 11/16 in.; and 93 in. EXACTLY!



  Supported by corporations who care about education in the construction industry.  
  Andersen Windows  
  Mastering FInish Carpentry DVDs