Shiplap Wall Calculator
Enter your wall dimensions and shiplap board specs to calculate total area, number of courses, boards needed, and nails required for installation.
Estimate only — not professional advice. Always verify results independently before purchasing materials or beginning work. Terms of Use
What is Shiplap Wall?
A shiplap calculator estimates the material needed to cover a wall with shiplap siding or paneling. Shiplap is a type of wooden board with a rabbet (notched edge) on each side that creates an overlapping joint between adjacent boards. When installed horizontally, each board overlaps the one below it, creating the characteristic shadow line and a weather-resistant surface. This calculator accounts for the overlap to determine the true exposed width, the number of horizontal courses, the total boards, and the fasteners needed. The critical measurement is the exposed board width, which is the actual board width minus the overlap on one side. A standard 1x6 shiplap board has an actual width of 5.5 inches and a typical overlap of 0.75 inches, yielding an exposed width of 4.75 inches. This exposed width determines how many horizontal courses (rows of boards) are needed to fill the wall height. Dividing the wall height in inches by the exposed width and rounding up gives the number of courses. Board quantity depends on the number of courses and the wall length. Shiplap boards are commonly sold in 8-foot lengths. If the wall is longer than 8 feet, each course requires multiple boards with staggered end joints. The calculator divides the wall length by 8 feet and rounds up for each course, then applies the waste factor. A 10 percent waste factor is standard for a rectangular wall with no openings. Walls with windows or doors may need 15 percent or more to account for cutoffs around openings. Nailing is essential for a professional, long-lasting installation. The standard practice is to face-nail with two nails at every stud crossing. Studs are typically spaced 16 inches on center in residential framing, so the number of stud crossings per course equals the wall length in inches divided by 16, plus one for the starting stud. Two nails per intersection prevents the board from cupping or twisting over time. Use 6d or 8d stainless steel ring-shank nails for exterior applications or 15-gauge finish nails for interior accent walls. Shiplap adds texture, warmth, and visual interest to both interior and exterior surfaces. It is commonly used for accent walls, ceilings, wainscoting, exterior siding, and bathroom or kitchen feature walls. Proper material estimation ensures the project stays on budget and avoids the frustration of mismatched boards from different production lots.
How to Calculate
- Measure the wall length in feet
- Measure the wall height in feet
- Check the actual board width in inches (not the nominal size — a 1x6 is actually 5.5 inches)
- Confirm the overlap dimension from the board profile (0.75 inches is typical)
- Set the waste factor (10% for simple walls, 15% for walls with windows or doors)
- Review the number of courses, boards needed, and nail count
- Subtract area for large openings and recalculate if needed
Formula
Wall Area = Wall Length x Wall Height Exposed Board Width = Board Width - Overlap Number of Courses = ceiling(Wall Height in inches / Exposed Board Width) Boards per Course = ceiling(Wall Length / 8 ft board length) Boards Needed = ceiling(Courses x Boards per Course x (1 + Waste / 100)) Number of Studs = floor(Wall Length in inches / 16) + 1 Nails Needed = Courses x Number of Studs x 2 The ceiling function rounds up to ensure complete coverage. Two nails per stud per course is the standard face-nailing pattern for shiplap.
Example Calculation
A 12 ft wide by 8 ft tall wall with 5.5-inch shiplap boards, 0.75-inch overlap, and 10% waste: Wall Area = 12 x 8 = 96 sq ft Exposed Board Width = 5.5 - 0.75 = 4.75 in Number of Courses = ceil(96 in / 4.75 in) = ceil(20.21) = 21 courses Boards per Course = ceil(12 / 8) = 2 boards Raw Boards = 21 x 2 = 42 boards Boards Needed = ceil(42 x 1.10) = ceil(46.2) = 47 boards (8 ft each) Number of Studs = floor(144 / 16) + 1 = 9 + 1 = 10 studs Nails Needed = 21 x 10 x 2 = 420 nails
Frequently Asked Questions
What is the difference between shiplap and tongue-and-groove?
Shiplap has a rabbet (L-shaped notch) on each edge that creates an overlapping joint. Tongue-and-groove has a protruding tongue on one edge that fits into a groove on the adjacent board, creating an interlocking joint. Shiplap leaves a visible shadow line gap between boards, while tongue-and-groove can create a tighter, more seamless surface. Both are installed similarly and use comparable quantities of material.
Should I install shiplap horizontally or vertically?
Horizontal installation is the traditional and most popular orientation, creating the classic shadow-line look. Vertical installation works well for accent walls and can make low ceilings feel taller. For exterior siding, horizontal installation sheds water better. The material calculation is the same either way — just swap which dimension you use for courses versus board lengths.
Do I need to acclimate shiplap boards before installation?
Yes. Stack the boards in the room where they will be installed for at least 48 to 72 hours before nailing them up. This allows the wood to adjust to the room's temperature and humidity, reducing expansion, contraction, and gaps after installation. This is especially important for solid wood shiplap; primed MDF or engineered boards are more dimensionally stable.
How do I handle electrical outlets and switches on a shiplap wall?
Use outlet box extenders to bring the boxes flush with the new wall surface. The shiplap typically adds 3/4 inch of depth. Mark and cut the board around each box using a jigsaw or oscillating multi-tool before nailing it up. Test-fit the cut board before applying adhesive or nails. The outlet cover plate should overlap the cut edges for a clean look.
What type of nails should I use for shiplap?
For interior walls, use 15-gauge or 16-gauge finish nails, 1.5 to 2 inches long, driven with a pneumatic or cordless finish nailer. For exterior siding, use 6d or 8d stainless steel ring-shank nails to resist corrosion and pull-out. Always nail into the studs, not just the drywall, for a secure hold.