The black diamond markings on a tape measure are used to indicate the spacing for I-beam floor joists or engineered wood joists, which are typically spaced every 19 3/16 inches. These diamonds help builders quickly locate where to place these joists in new construction, especially for flooring and roofing framing. This spacing is different from the more common 16-inch spacing used for wall studs, which is usually marked in red on the tape measure. The black diamonds thus serve as a quick reference for the layout of structural components like floor joists or roof rafters, aiding in efficient and accurate construction work. The 19 3/16-inch spacing also aligns well with standard plywood sheet sizes, making it practical for construction
. In summary:
- Black diamonds appear every 19 3/16 inches.
- They mark the typical spacing for I-beam floor joists or roof rafters.
- They are distinct from the red marks at 16 inches, which indicate wall stud spacing.
- This feature helps builders quickly measure and lay out joists without extra calculations
