What problem this solves
Plank direction is one of those decisions that look trivial on paper but affect how the room reads for years. Run the planks perpendicular to the main window and seams don’t cast shadows; run them parallel to the window and every seam throws a small shadow across the floor. Run them along the primary traffic path and feet slide over the planks smoothly; run them across and feet catch the seams. Run them along the longest wall and you minimise cuts; run them across and you may add 5% to waste.
Modern installers balance all three factors with weighted priorities: light direction first (because the eye sees it most), then traffic (because the body feels it), then room shape (because the budget sees it). The calculator applies the same priority order and tells you the winner plus why.
Who it’s for
- Flooring installers laying planks in a new build
- Homeowners DIY-ing a floor and unsure which way to run the planks
- Designers specifying direction in floor-plan drawings
- Contractors quoting a flooring job
Why the rules can conflict
In a long, narrow room with a window on the short wall and traffic running along the length, the rules align: planks along the long axis perpendicular to the window. In a square room with traffic diagonally, the rules conflict: light says parallel-to-traffic, traffic says along-its-direction, room shape says along-the-longest-wall. The priority order breaks the tie.
Limitations
- Single room only; multi-room directions need a layout plan.
- Threshold matching (same direction across multiple rooms) not modelled.
- Diagonal traffic and complex paths use simplified rules.
- Light direction assumes a single main window; rooms with multiple windows need a weighted average.
- Wide-plank floors (≥ 25 cm) hide seams; the rules matter less.
Practical rules of thumb
Most designers default to running planks along the longest wall and perpendicular to the main window. This works for most rooms. For hallways, run planks along the length (so seams don’t catch traffic). For bedrooms, run toward the window (light rule). For open-plan living/dining, choose the dominant traffic axis. Always match direction across thresholds to avoid awkward seams at the doorway.