Worked layout
Horizontal shiplap coverage
Example measurements
- Wall
- 120 × 96 in
- Actual board face
- 6 in
- Installed coverage
- 5½ in
- Starting edge
- Bottom
Layout result
- Orientation
- horizontal
- Courses
- 18
- Final visible face
- 2 1/2 in
Measure board width and installed repeat separately
Dimensions are in inches. On a small screen, scroll the drawing to inspect each endpoint.
Compare on the same wall
Only the named layout setting changes. Wall measurements stay the same.
horizontal courses
5 1/2 in installed coverage · 18 pieces on Wall A
Try this variation →vertical courses
5 1/2 in installed coverage · 22 pieces on Wall A
Try this variation →Measure what joined boards add to the wall
Lay several boards together using the engagement and any gap specified for the exact product. Mark the same profile edge on successive boards, such as the same shoulder, then measure across several repeats. Divide that distance by the number of intervals between the marked edges. Counting the boards instead of the intervals would give the wrong installed module.
Compare the result with the manufacturer’s published coverage. A loose board includes the lap or tongue that may be hidden after assembly. Measuring just a decorative flat face can miss part of the repeat in the other direction. The quantity you need is the advance of the joined pattern, including a specified gap only when it belongs in that installed module.
A profile name does not supply a coverage dimension
Nickel-gap, tongue and groove, and shiplap identify kinds of profiles or appearances; they do not guarantee interchangeable dimensions. Record the exact product, physical width, installed repeat, thickness, and stock length. Use a sample of the intended profile and finish if the product sheet leaves any of those unclear. The table distinguishes what must be measured from what the calculator can infer.
| Profile label | Required measured installed face | Engine behavior | The engine does not infer |
|---|---|---|---|
| Shiplap | Advance after the specified lap engages | Uses the entered installed face | Hidden lap geometry |
| Tongue & Groove | Repeat after the specified tongue engagement | Uses the entered installed face | Tongue seating or movement clearance |
| Beadboard | Repeat of the selected board or sheet product | Uses the measured face | Bead pitch as a substitute for coverage |
| Nickel-gap | Repeat with the product’s built-in or specified gap | Uses installed-face coverage | A universal coin-sized spacer |
| Custom | Equivalent-edge repeat of the actual assembly | Uses the measured face | Unspecified overlap or joint detail |
Keep coverage and stock length in separate fields
Coverage determines how many courses or columns cross the wall and how much of the final one is visible. Stock length determines whether the required runs fit the boards you buy. Look at both in the worked example. A longer board cannot fix an incorrect coverage measurement; entering the loose board width as coverage can change every repeated position.
The linked Metrie prefinished-shiplap page provides that product’s dimensions, coverage, and starting-board guidance. Use it for that product. If you choose another board, use its own current documentation for engagement, fastening, and orientation. A shared shiplap label is not enough to transfer the installation details.
Decide where the partial face should finish
Find the final visible strip in the drawing. A small remainder beside prominent window casing is a different design choice from a strip largely concealed beneath crown or above baseboard. Compare starting with a full face against a planned offset that changes the two exposed edges. Judge their locations on the wall, not only the size of the remainder.
A partial face still has to be cut from a suitable physical blank. Check which joining edge must remain, and whether the proposed rip preserves the profile’s engagement and permitted fastening area. The coverage outline locates the strip; the selected product’s detail determines how that edge can be made.
Check repeated positions from a fixed start line
Mark several checkpoints as distances from the same starting line. Compare the joined sample with those positions before covering a large area, then use them to check progress. Stepping a rounded displayed width from one board to the next can accumulate an error even if each individual step looks close.
If the sample’s repeat disagrees with the product sheet, check the product variant, joint engagement, and the edges used for measurement. Resolve the difference before calculating the order. Substituting a convenient nominal width would leave the disagreement hidden until an opening or finishing edge exposes it.
Questions about this layout
Is nominal 1×6 the installed coverage?
Not necessarily. Check the stated coverage for the exact product and compare it with the joined repeat. The loose board can include a lap or tongue that disappears in the installed assembly.
Should I add a gap to the coverage field?
Include a specified gap only when it belongs in the installed repeat and has not already been counted. Follow the product’s joint detail; the name nickel-gap does not supply a universal spacer dimension.
Does a narrower final face mean I can buy a narrower last board?
Only if a compatible piece can supply the required shape and joining edge. Otherwise retain a suitable full blank to cut down. A small visible strip is not evidence that a smaller purchased board will fit the assembly.
Sources and assumptions
- Metrie: Prefinished Matte ShiplapProduct-specific dimensions, coverage, starting-board alignment, opening cuts, and orientation guidance. Apply the instructions for the product you actually buy.
- TrimLayout Calculation MethodsDefinitions of clear gaps, measurement references, finished pieces, and material allowances used in these examples.
- NIST: SI Units — LengthUnit relationships for converting measured lengths; this source does not prescribe decorative proportions.