Layout model and usable dimensions
A shiplap profile overlaps, so its exposed coverage is narrower than its overall board width. This tool uses the true exposed width to count horizontal rows and divides each row into stock lengths before adding spare boards. It intentionally does not transfer offcuts from one row to another, giving a conservative source-board estimate you can compare with an optimized cut list. It also reports the final row height so you can consider balancing the top and bottom cuts. Openings, joint staggering, stud locations, fastening, and profile direction still belong in the actual layout.
Fit, direction and offcut constraints
- The no-reuse source count may exceed an optimized cutting schedule substantially.
- Stock joints may require support and specific staggering; the arithmetic does not design fastening.
- For vertical shiplap, swap wall directions and interpret rows as columns.
Layout arithmetic and example
A worked example
An 8 ft wall requires 18 rows at 5.5 inches coverage. A 14 ft run plus trim uses two 12 ft source boards per row; two extras bring the conservative estimate to 38.
Measure and compare a layout
- Measure the wall in the intended board direction.
- Use actual exposed coverage after overlap.
- Review source boards per row and improve the offcut plan where permitted.
Frequently asked questions
Should I use nominal shiplap width?
No. Use the exposed coverage after the overlapping profile.
How many 5.5 inch rows cover an 8 ft wall?
96 ÷ 5.5 rounds to 18 rows, leaving a 2.5-inch final exposed row when the first row stays full width.
Does it reuse shiplap cutoffs?
No. Each row is budgeted separately; a planned cut list can improve yield.
Calculation method: JICWH methodology. Examples are planning assumptions, not product recommendations.