
While working on some stuff around the house this weekend, the question arose of what those little black diamonds were every 19-3/16." The question was brought to work today and answered by the greatness that is Wikipedia.
So under a normal 8-ft piece of plywood, if there are 5 spaces, there will be 6 different supports. And you don't even have to figure out the correct spacing to be exact. How sweet is that? I for one, can't wait to build a roof in the near future, because it will be soooo much more efficient."One little-known feature on most tape measures is
a small black diamond that appears every 19.2 inches, known as the 'black truss'
markings. This is used to mark out an equal five trusses per standard eight-foot
sheet of building material. (8 feet, or 96 inches, divided by 5 is 19.2
inches.)"