Posted By RichC on February 1, 2020
I’ve used tape measures for decades both when working in construction (summer job) and for hundreds of home improvement projects .. YET never really knew why the 19.2" on center diamond mark was on tapes.
Most building codes mandate that studs be spaced 16 inches apart, so the tape will help you stay on the right side of the law as you construct (as well as making sure your wall can safely bear the load it needs to).
Joists on the other hand should be 19.2 inches apart. Since plywood often comes in 8-feet sections, you’re in luck. Divide 8 feet (or 96 inches) by 19.2 and you get 5.