TrimTally / Guide
Board and batten edges: two spacing formulas
Compare flush edge battens with equal end gaps using the same wall. Understand why the gap count changes and avoid a common layout mistake.
Count spaces, not just boards
Seven boards can make six, seven or eight visible spaces depending on what happens at the wall ends. This site supports two explicit conventions: a board flush at each end, or equal empty gaps at both ends. Select the convention before calculating.
Flush at both edges
Subtract all board widths from the wall width, then divide by one less than the number of boards. For a 122-inch wall with seven 2-inch boards, the calculation is (122 − 14) ÷ 6 = 18 inches. The first left edge is zero; the final board starts at 120 inches and ends at 122.
Equal gaps including the ends
Subtract the same board widths, but divide by one more than the board count. The example becomes 108 ÷ 8 = 13.5 inches. The first board starts 13.5 inches from the wall end. Each next board starts another 15.5 inches along, accounting for the gap plus the 2-inch board.
Do not mix a clear gap with a centre mark
With identical board widths, centre spacing equals the clear gap plus one board width. Neither number is the same as the left-edge location of a particular board. A labelled position list helps a second person understand your marks.
Corners need their own decision
An inside corner can make the visible width of an end board different from its physical width. Doors, skirting returns and adjacent walls can also change the useful working width. Treat those details as measured constraints; this page’s flat-wall examples do not resolve joinery or installation requirements.
Questions, answered
What about only one edge board?
That convention is not included in this version. Do not use a two-edge result and remove a board without recalculating the layout.
Will rounding each gap fit exactly?
Not always. Use the unrounded positions as your reference and verify both final edges before installation.