Board and batten spacing, inside and out
Indoors, no code, maker or trade body sets batten spacing, so the arithmetic is the whole rule. The clear gap is the wall width minus the battens' combined width, divided by the number of gaps between them. An 8 ft wall with 1x3 battens and a 12 inch target gap takes 7 battens. They have to land evenly, so the clear gap comes out at 13 1/16 inches. Outdoors the siding makers and the cedar association set the batten's width, its overlap on the boards beneath and where it has to fall.
In brief
- Inside: clear gap = (wall width minus battens × batten width) ÷ (battens minus 1). Pick a target, let the calculator even it out.
- Actual batten widths: 1x2 is 1 1/2 in, 1x3 is 2 1/2 in, 1x4 is 3 1/2 in.
- Cedar siding: 6 in boards set 1/2 in apart, battens overlapping each board edge by at least 1/2 in, one nail per bearing through the gap.
- Fiber cement panels: battens span each panel joint by at least 3/4 in on each side; the maker's batten is 3/4 by 2 1/2 in, fastened every 16 in.
- Engineered-wood panels: no-groove panel, studs at most 16 in (24 for one series), never a batten across a horizontal seam.
Inside: a formula, not a standard
No building code, siding maker or lumber association publishes a spacing for an interior board and batten accent wall. The battens carry no load and cover no joint, so the spacing is a look. The arithmetic is fixed, though, and it is where most walls go wrong. A batten sits at each end of the wall, so for n battens there are n minus 1 gaps. The clear gap is the wall width minus n times the batten width, divided by n minus 1. The batten width is the dressed size, not the nominal one. By the softwood lumber standard, a 1x2 is 1 1/2 inches, a 1x3 is 2 1/2 and a 1x4 is 3 1/2. Pick a target gap, solve for the batten count nearest it, and accept the gap that count gives.
| Wall | Batten | Target gap | Battens | Clear gap | On center |
|---|---|---|---|---|---|
| 8 ft | 1x3 | 12 in | 7 | 13 1/16 in | 15 9/16 in |
| 10 ft | 1x2 | 8 in | 13 | 8 3/8 in | 9 7/8 in |
| 12 ft | 1x4 | 16 in | 8 | 16 9/16 in | 20 1/16 in |
| 20 ft | 1x3 | 24 in | 10 | 23 7/8 in | 26 3/8 in |
The 8 ft wall shows why targets move. With 1x3 battens a true 12 inch gap would need 7.45 battens, so 7 battens give 13 1/16 and 8 give 10 7/8. Either is even. The number people argue about, "on center", is the clear gap plus one batten width. A wall described as "16 on center" with 1x4 battens has 12 1/2 inch gaps. Windows and doors change the count. Measure each run of wall between them separately, and keep one gap width across the whole room where it can be seen. Let the runs that meet trim absorb the difference. The board and batten calculator takes the wall, the batten stock and the openings. It draws the layout and counts battens, sheet or board backing, rails and nails.
Outside: the boards set the spacing
Exterior board and batten is a weather joint. The batten's job is to cover the gap between the boards under it and the fasteners. Its position is fixed by the boards, and its width by the overlap the material needs.
With cedar boards, the Western Red Cedar Lumber Association's instructions set nominal 6 inch boards 1/2 inch apart to allow for movement. Battens overlap each board edge by at least 1/2 inch, more for wider boards. Its suggested pairing is 1x3 battens over 1x10 boards, which puts a batten every 9 3/4 inches. Boards up to 6 inches get one nail per bearing through the center. The batten gets one nail per bearing driven through the gap between the boards, so that no nail pins two pieces together. That is because, in the association's words, nailing overlapping pieces together restricts movement and causes splitting. Vertical siding needs horizontal blocking or furring to nail into, at 36 inches on center face-nailed over sheathing, 32 blind-nailed, 24 with no sheathing. The nails penetrate 1 1/4 inches into framing, and the bottom of the siding stays 6 inches off the ground.
With fiber cement panels, James Hardie's product data wants a batten strip spanning each vertical panel joint by at least 3/4 inch on each side. Its own batten board is 3/4 by 2 1/2 inches in 12 ft lengths, fastened at no more than 16 inches on center. Joints fall on studs, so the structural battens land every 4 ft. Its 2013 technical guide for multifamily work describes vertical battens at typically 12 to 16 inches on center. The extras between the joints are decorative and need their own backing where they miss a stud.
With engineered wood panels, LP SmartSide's application instructions use the no-groove panel for a board and batten look. It is framed on studs at no more than 16 inches on center for most series and 24 for the 190 series. It is nailed every 6 inches around the perimeter and 12 in the field. The instructions forbid running a batten across a horizontal panel seam, which must be flashed. LP's trim instructions let trim under 3 inches wide serve as battens with one nail per width at most every 36 inches up the wall. Its pages pair 5/8 by 2 1/2 inch battens with the panel. A 16 inch wide vertical siding board puts a batten every 16 inches at minimum; panels let you choose the interval.
Counting the material
Battens are bought by the stick. The calculator rounds each wall's batten count up to full 8, 10 or 12 ft lengths and adds the waste you set. The backing, boards, plywood or primed sheet, is figured from the wall area less the openings. The top rail and baseboard, if used, are figured by the linear foot. Nails for interior work are about 2 per foot of batten plus 4, which is 20 for an 8 ft stick. The exterior fastener schedules replace that count outdoors. Before the rail, a 12 ft by 8 ft wall with eight 1x4 battens is 64 ft of batten, or eight 8 ft sticks. It also takes 160 nails and three 4 by 8 sheets of backing.
Questions about batten spacing
What is the standard spacing for board and batten?
Indoors there is none. Common design targets run 10 to 24 inches, with no published standard behind them, and the right one is whatever divides your wall evenly with a batten at each end. Outdoors the spacing follows the boards. Cedar boards about 6 to 10 inches wide put a batten over every joint. A 16 inch vertical siding board puts one every 16 inches. A fiber cement panel needs one at each 4 ft joint, with any extras between for looks.
How do I space battens evenly on a wall?
Count the battens, including one at each end, and subtract their total width from the wall width. Then divide by the number of gaps, which is one fewer than the battens. A 12 ft wall with eight 1x4 battens has 144 minus 28 = 116 inches of gap over 7 gaps, 16 9/16 inches each. Mark the first batten's edge, then each next one at the gap plus the batten width.
How wide should battens be?
For cedar siding with a 1/2 inch board gap, the batten must cover the gap plus at least 1/2 inch on each edge. That is 1 1/2 inches at the minimum, and a 1x3 at 2 1/2 inches in practice. The cedar association suggests 1x3 battens with 1x10 boards. James Hardie's batten is 3/4 by 2 1/2 inches. Inside, 1x2, 1x3 and 1x4 stock all work, and the wider the batten the fewer you need for the same look.
How many battens for a 10 ft wall?
At an 8 inch target with 1x2 battens, it takes 13 battens with a clear gap of 8 3/8 inches. At a 12 inch target with 1x3 battens, it takes 9 battens with a gap of 12 3/16 inches. At a 16 inch target with 1x4, it takes 7 battens 15 15/16 inches apart. The board and batten calculator draws the wall and counts the sticks, boards and nails.
8 source documents
- Western Red Cedar Lumber Association, Installing Board and Batten Siding: 6 in boards 1/2 in apart, battens overlapping at least 1/2 in, 1x3 battens with 1x10 boards, one nail per bearing. Read 2 November 2026.
- Western Red Cedar Lumber Association, Siding pre-installation tips: vertical siding nailed to blocking at 36, 32 or 24 in on center; 1 1/4 in nail penetration; siding 6 in off the ground. Read 2 November 2026.
- James Hardie Building Products, HardiePanel vertical siding product data, December 2019: batten strips span the vertical joint by at least 3/4 in on each side. Read 2 November 2026.
- James Hardie Building Products, HardieTrim boards product data, September 2019: batten boards 3/4 in thick, 2 1/2 in wide, 12 ft long; fasteners a maximum of 16 in on center. Read 2 November 2026.
- James Hardie Building Products, HardiePanel vertical siding technical guide, September 2013: vertical battens typically 12 to 16 in on center, multifamily guide, 2013 edition. Read 2 November 2026.
- Louisiana-Pacific, LP SmartSide panel siding application instructions, April 2026: no-groove panel for board and batten; studs at most 16 in (24 for the 190 series); 6 and 12 in nailing; no batten across a horizontal seam. Read 2 November 2026.
- Louisiana-Pacific, LP SmartSide trim and fascia application instructions: trim under 3 in wide used as battens gets one nail per width at most every 36 in. Read 2 November 2026.
- NIST and the American Lumber Standard Committee, Voluntary Product Standard PS 20-20, Table 3: nominal 1x2, 1x3 and 1x4 boards are 1 1/2, 2 1/2 and 3 1/2 in wide and 3/4 in thick dressed. Read 2 November 2026.