Board and Batten Siding Calculator

What board and batten siding is

Board and batten is a vertical siding style built from two parts. Wide boards, commonly 8, 10, or 12 inches nominal, hang on the wall in a row with a deliberate gap between neighbors. Narrow battens, usually 2 to 3 inches wide, then cap each gap, which keeps water out of the joint and creates the deep shadow lines the style is known for. The same pattern works on wood, fiber cement, engineered wood, and metal panels, and it reads as a modern barn look on homes and outbuildings alike.

The layout runs on on-center spacing. A 12 inch on-center layout means the centers of neighboring boards sit 12 inches apart, and the battens land on the seams between them. On a 20 foot wall, 20 x 12 = 240 inches, and 240 / 12 = 20 board positions, so 20 boards cover the run and one extra batten finishes the far edge. Counting positions this way, instead of guessing by eye, is what keeps the final course from landing on a sliver at the corner.

Boards and battens move with humidity, so the system is designed to float. Boards are fastened through their centers with a single nail line that lets the edges expand and contract, while battens bridge the joints and nail down across two boards. Respecting that movement, along with the waste factor covered below, is what separates a wall that looks flat for decades from one that cups and opens at the seams.

Measuring the wall and subtracting openings

Start with the gross area of each wall as a plain rectangle: length times height. A wall 20 feet long and 10 feet high has 20 x 10 = 200 square feet of face before any deduction. Measure each wall separately, because gable ends, bump outs, and garage walls rarely match, and a single blended average hides the walls that need the most material.

Next, subtract every opening the siding will not cover. Windows and doors are simple rectangles, so a 3 by 5 foot window removes 3 x 5 = 15 square feet. On the 200 square foot wall above, the net area becomes 200 - 15 = 185 square feet. Deduct only what the siding skips; trim, corner boards, and the battens themselves all stay in the count because they are part of the system you are buying.

Two measurement habits prevent the classic mistakes. First, record every wall with its own length and height, not a total perimeter, because the board count for a 24 foot wall differs from two 12 foot walls when corners get trim. Second, photograph each elevation before ordering. Photos let you recheck opening sizes without a second trip up the ladder, and they catch the one window the tape measure missed.

Choosing board width, batten width, and spacing

Three choices set the look and the count: board width, batten width, and on-center spacing. Common nominal board widths are 8, 10, and 12 inches, with actual dressed widths running about half an inch narrower, so an 8 inch nominal board measures close to 7.25 inches face. Battens usually run 2 to 3 inches wide, wide enough to bridge seasonal movement on both sides of the seam.

Spacing ties the three numbers together. On-center spacing equals board width plus the gap the batten will cover, so a 10 inch board under a 12 inch on-center layout opens about a 2 inch gap, which a 2.5 inch batten overlaps on both edges. Narrower spacing raises the board count and the shadow frequency; wider spacing does the opposite. Match the rhythm to the scale of the wall: a long garage wall carries 12 or 14 inch spacing comfortably, while a small dormer looks better at 8 or 10.

Counting boards, battens, and linear feet

With spacing fixed, the counts follow directly. Boards per wall equals wall length in inches divided by the on-center spacing, rounded up to the next whole board. Battens take one extra piece, because a batten caps the seam at each interior position plus the final edge, so battens equal boards plus one. Linear feet is then board count times wall height, and the same for the batten run.

On the 20 foot wall at 12 inch spacing, the count is 240 / 12 = 20 boards and 20 + 1 = 21 battens, and each piece runs the full 10 foot height. That wall needs 20 x 10 = 200 linear feet of board and 21 x 10 = 210 linear feet of batten before waste. Repeating this arithmetic wall by wall is exactly what the widget automates, including the rounding that keeps partial positions honest.

Tall walls change the material plan without changing the count logic. If the wall is 18 feet high and boards come in 12 foot lengths, each vertical run needs a scarf joint, so buy boards with the offcut pattern in mind and plan the joint over a batten line. Short offcuts are not trash: they become the filler courses at gable rakes, where the triangle eats scraps that a straight wall would not.

Worked example 1: 20 ft wall with a window

Take a single gable wall 20 feet long and 10 feet high, with one 3 by 5 foot window. Gross area is 20 x 10 = 200 square feet. The window removes 3 x 5 = 15 square feet, so net area is 200 - 15 = 185 square feet. The design calls for 10 inch boards, 2.5 inch battens, and 12 inch on-center spacing.

The board count is 20 x 12 = 240 inches of wall, and 240 / 12 = 20 board positions, so 20 boards cover the run. Battens take 20 + 1 = 21 pieces. Each board and each batten runs the full 10 foot height, so board footage is 20 x 10 = 200 linear feet and batten footage is 21 x 10 = 210 linear feet before waste. Adding the standard 10 percent for cuts and defects gives 200 x 1.10 = 220 linear feet of board and 210 x 1.10 = 231 linear feet of batten, which rounds up to 22 boards and 24 battens at the lumberyard.

The rest of the order follows the net area. House wrap covers the whole wall with overlap allowance, so 185 x 1.15 = 212.75 square feet, and a 100 square foot roll falls short of covering it, so plan on 3 rolls of 100 square feet to keep laps clean. Nails run about one ring shank nail per square foot of siding on the boards plus battens, so figure 212.75 x 2 = 425.5, which rounds up to about 430 nails, or roughly 2 pounds of 8d hot-dip galvanized ring shank.

Worked example 2: 24 ft garage wall

Now a windowless garage wall 24 feet long and 8 feet high, to be sided with 8 inch boards at 8 inch on-center spacing. Gross and net areas match because there are no openings: 24 x 8 = 192 square feet. The wall length in inches is 24 x 12 = 288, and the board positions come out as 288 / 8 = 36 runs. Battens follow with 36 + 1 = 37 runs.

Each board runs the 8 foot height, so board footage is 36 x 8 = 288 linear feet. Applying a 12 percent waste factor for the tighter spacing gives 288 x 1.12 = 322.56 linear feet, which rounds to 323 linear feet of board. The batten run is 37 x 8 = 296 linear feet, and 296 x 1.12 = 331.52, rounding to 332 linear feet. Both numbers land close to the widget output for the same inputs, which is the point of checking one wall by hand before trusting the tool on the rest of the house.

House wrap for this wall is 192 x 1.15 = 220.8 square feet, so 3 rolls of 100 square feet cover it with laps. Nails follow the same per square foot logic: 220.8 x 2 = 441.6, which rounds up to about 450 nails, roughly 2 pounds of 8d ring shank. Because there are no windows, the only flashing needed is at the bottom starter strip and at the top where the siding meets the soffit.

Waste factors, wrap, and fasteners

Waste is not optional on board and batten. Every cut end, every damaged board, and every gable angle comes out of the pile, so the standard allowance is 10 percent on simple rectangular walls and 12 to 15 percent on gables, tighter spacing, or boards with visible character grades. Dense spacing on the second worked example is why its factor was 12 percent instead of 10: more runs mean more cuts and more chances to split a board edge.

House wrap or a vapor permeable barrier goes on before the first board, and it needs overlap to do its job. A 15 percent factor over net area covers the horizontal laps and the corner wraps. Starter strip and drip cap close the bottom edge against splash and capillary water, and corner boards box both outside corners so the field never has to be mitered.

Fasteners matter as much as counts. Use 8d (2.5 inch) hot-dip galvanized or stainless ring shank nails so the boards cannot back off the wall as they move, and keep nails away from board edges by at least three-quarters of an inch. Stainless is worth the premium near the coast or on cedar, where plain galvanized can streak the finish within a few seasons.

Material choices and installation basics

The same layout math applies across materials, but each substrate changes the details. Wood is the classic choice and takes stain well, though it wants a rainscreen gap in wet climates. Fiber cement holds paint for a decade or more and resists fire and insects, at the cost of heavier boards and carbide blades. Engineered wood splits the difference with a factory primer and lighter weight, while metal panels arrive preformed with integral battens that remove the batten count from the order entirely.

Installation follows one sequence on every wall. Wrap the wall, flash openings, snap the on-center lines, hang boards plumb from the starter strip, then cap the seams with battens set to a consistent reveal. Check plumb every third board rather than at the end, because a drift of a quarter inch per board compounds into a visible lean by the last course. The WRCCA and manufacturer guides cover substrate specific details, and local building codes set the fastening schedule in high wind zones.

For references on the underlying materials, see the Western Red Cedar Lumber Association for wood siding guidance, the EPA renovation rules if the wall predates 1978, and NIST publications on moisture management in walls.