Board and Batten Calculator

A board and batten wall is a pattern, and the pattern almost never divides the wall evenly. This calculator takes the wall and two choices — how wide the boards are and how wide the gap behind each batten is — and turns them into a shopping list: how many boards, how many battens, how many rows of furring strip, and how much of each material to bring home.

It is meant for the person who is about to buy the timber: an accent wall in a hallway, a half-height panel behind a sofa, a garage wall or a garden-room wall. You can use it to build the order yourself, to check a builder’s takeoff, or to answer the question that comes before the order — will the pattern even fit?

Two details make it more useful than a single division. First, you can start from whichever measurement you already have: give the wall width and height, or give a wall area plus one dimension and the other one is worked out for you. Second, doors and windows are treated as an allowance rather than ignored, so the totals stay sensible when the wall is not a plain rectangle.

Five steps describe the job. Everything else on the page follows from them.

A wall you can check by hand

A 3 m wide, 5 m high wall, sided with 5 cm boards and 8 cm gaps, with no openings. The pitch is $5 + 8 = 13\ \mathrm{cm}$. Entered in centimetres, the wall width is 300, and the extra gap in the numerator puts a board at each end:

That fraction is the honest answer: 23 whole boards plus a sliver. The page reports 24 boards, because a sliver is still a board you have to buy and rip, and it reports 23 battens for the 23 seams between them.

The furring rows follow the height at one row every two feet, plus the row at the base:

That is 9.2 rows, which the page shows as 9. The strip total, though, uses whole rows, because you cannot buy four-fifths of a row: 10 rows of a 3 m wall is 30 m of strip. Board and batten material are the whole pieces times the height, so this wall needs 120 m of board and 115 m of batten, plus 6 m of trim for the two 3 m rails.

Reading the results

Every relationship below runs both ways where it sensibly can: give a wall area together with one dimension and the other dimension is solved. The counts and material totals are results, so they follow your inputs rather than being typed into.

The board count

With $n$ boards there are $n - 1$ gaps, so a wall of width $W$ built from boards of width $b$ and gaps of $s$ satisfies $W = n\,b + (n-1)\,s$. Solving for the count gives the formula the page uses:

The extra spacing in the numerator is what puts a board, rather than a gap, at each end of the wall. It is also why the result is rarely a whole number: the pattern simply does not have to divide the wall evenly.

Battens

One batten covers one internal seam, and the count rounds the boards up first so a batten exists for the seam next to the ripped board:

Furring strip

The rows are horizontal supports fixed to the wall behind the boards, one every 2 ft (0.6096 m) of height plus the row at the base, and each row runs the full wall width:

If you would rather work to a fixed number of rows, typing that number works back to the height it implies, $H = 0.6096\,(R - 1)$. That is useful when you want a row at a particular height, and confusing if you only meant to change the count.

Material totals and the opening allowance

Board and batten material are lengths, not areas: every board and every batten runs the full height, so the totals are the whole pieces times the height. Doors and windows then take their own allowance off that run:

The same arithmetic gives the batten total with $\left\lceil N_{\mathrm{battens}} \right\rceil$ in place of the board count. The run is worked in feet because the allowance is quoted in square feet, then shown in the length unit you selected. The allowance is subtracted as an area, which is a simplifying convention rather than a board-by-board cut list: a standard 7 ft by 5 ft door removes 35 ft² of allowance from the run. Treat the material totals as a purchasing allowance, and plan the actual cuts around each opening on the wall.

Trim

Rounding, and where it can surprise you

• The board and batten counts are shown as whole numbers, and their material totals use the next whole piece. When the exact board count rounds down — say 23.3, shown as 23 — the material total still pays for 24 boards, because the pattern needs that sliver.
• The row count is shown to the nearest whole row, while the strip total uses the next whole row. A 9.2-row wall reads as 9 rows and 30 m of strip, not 27 m.
• Material totals are rounded to whole units of the length unit you chose, and trim to one decimal place, so a total can differ from a hand calculation by less than one unit.

Units

Lengths accept centimetres, metres, inches, feet and yards, and the wall area accepts the matching square units. Whatever mix you enter is converted before the arithmetic, so a width in feet, a board width in centimetres and a height in metres all combine correctly.

Two situations that behave differently from the plain wall above: one where the pattern has to fit around openings, and one where you start from an area instead of a width.