Layout: batten, board, batten
Board and batten alternates wide boards with narrow battens covering the seams. The layout math: <strong>each board plus its batten plus one gap forms a repeating unit</strong> across the wall. The calculator finds how many units fit your wall and adjusts gaps so the pattern lands evenly at both ends.
Wood moves — plan the gap
Wide boards shrink and swell across the grain with humidity; a 12-inch pine board can move a quarter inch seasonally. Battens are nailed to only one board so the assembly can slide, and the gap left today closes tomorrow. Acclimate the boards to the wall's climate for a week before installation.