How do you calculate board and batten spacing?

Add the board width and the gap to get one repeating unit, then divide the wall width by that unit and round to the nearest whole number of boards. A batten covers each gap between boards, so the number of battens is one less than the number of boards for a run that starts and ends on a board.

How wide should the battens be?

The batten must be wider than the gap it covers so it laps onto the boards on each side. A batten around 40 to 65mm over a gap of about 40 to 50mm is common. Wider boards with wider gaps give a bolder look, while narrower spacing gives a busier, cottage feel.

How much extra should I allow for waste?

Add about 10 percent to the board and batten lengths for cutting, offcuts and the odd damaged length, and more if the wall has many windows and doors to cut around. Buy battens for corners and end trims separately, as this calculator counts only the battens over the gaps.

Board and Batten Calculator

This board and batten calculator works out how many vertical boards and battens you need to clad a wall, plus the total lengths to buy, so you can price up a board and batten feature wall, gable end or exterior cladding run with confidence. Board and batten is the classic look of wide boards set with a gap between them, with a narrow batten fixed over each gap to cover the join. Enter the width and height of the wall, the width of your boards, and the gap you want between them, and the calculator adds the board and the gap into a single repeating unit, divides the wall by it, and rounds to a whole number of boards for even spacing. It then counts a batten over each gap and multiplies both by the wall height to give the metres of board and batten you need. Use it to compare looks quickly: wider boards with wider gaps use fewer lengths and read bolder, while tighter spacing gives a busier cottage feel. Remember to add around 10 percent for waste and offcuts, buy extra battens for corners and trims, and adjust the count if the wall has large windows or doors to work around. Measurements are a guide for planning and ordering.

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Wall width (m)

Wall height (m)

Board width (mm)

Gap between boards (mm)

vertical boards across the wall

Battens over gaps23

Total board length64.8 m

Total batten length62.1 m

A 6 m wide wall takes about 24 boards 200 mm wide with a 50 mm gap, plus 23 battens over the gaps. That is 64.8 m of board and 62.1 m of batten at 2.7 m each.

Counts battens over the gaps only. Add about 10% for waste, plus extra battens for corners and trims, and adjust for windows and doors. Estimate only.

How it works

The board and the gap next to it form one repeating unit. Dividing the wall width by that unit and rounding to a whole number gives the number of boards that fit with even spacing. Because the run starts and ends on a board, there is one gap between each pair of boards, so the number of battens is one less than the number of boards. Multiplying each count by the wall height gives the total metres of board and of batten to order. Rounding keeps the spacing tidy, so the real gap will sit very close to the figure you entered.

Worked example

Take a wall 6.0 m wide and 2.7 m high, clad with 200 mm boards and a 50 mm gap. The repeating unit is 200 plus 50, or 250 mm. Dividing 6,000 mm by 250 gives 24 boards. With a board at each end there are 23 gaps, so you need 23 battens. Each length runs the full 2.7 m height, so the boards use 24 times 2.7, which is 64.8 m, and the battens use 23 times 2.7, which is 62.1 m. Add around 10 percent to each for waste before you order.

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