All articles · 5 min read

Which direction should floorboards run?

The main rule: lay the boards along the room's longest dimension and parallel to the light from the main window — but the subfloor can override both.

The three rules, in order of priority

There is no single right answer to which way floorboards should run, but there is an order to decide it in. The construction rules first, the home as a whole second, and aesthetics last.

1. The construction: if the boards must carry load, they run across the joists or beams. That is not up for debate.
2. The home as a whole: the floor should run the same direction through connected rooms, so there is no change of direction in an open doorway.
3. Light and length: parallel to the light from the main window, and along the room's longest dimension.

Rule 1: Across the joists

If you are laying a solid wood floor on joists — boards that carry the load themselves between the supports — the boards must run perpendicular to the joists. Otherwise a board has no support beneath it, and the floor springs and creaks. Joists are typically spaced 60–80 cm apart, and each board must cross several of them.

The same rule applies if you are laying a floor directly on visible floor joists in an older house: the boards go across the joists. This is often why the floor in an old house runs "the wrong way" relative to the window — the joist layout decided it a hundred years ago.

If instead you are laying a floating click floor (laminate, click-vinyl, engineered parquet) on a flat subfloor with an underlay, the floor carries nothing. Then the direction is free, and the home as a whole and the light decide it.

Rule 2: Same direction throughout the home

If the floor runs through several rooms without a threshold — living room, hall, kitchen-diner — it should have one continuous direction. A change of direction in the middle of an open passage looks like a mistake, and needs a transition strip or a cross-laid border row to avoid fraying.

In practice this means you choose the direction based on the longest unbroken axis in the home, not the individual room. If the home has a long hallway tying the rooms together, the hallway almost always wins: lay the boards along the hallway, and carry that direction into the rooms.

This is easier to see on a floor plan than to picture. A measured plan of the whole floor — scanned with the iPhone's LiDAR or drawn by hand in HouseSense — shows straight away where the longest unbroken line runs, and which doorways are open passages rather than closed doors.

Rule 3: Parallel to the light, and along the room

The light: lay the boards so they run away from the largest window, that is, parallel to the light rays entering the room. Then the light falls along the joints rather than across them, and the thousand small cross-joints cast no shadow. Lay the boards across the light, and every single end joint draws a small shadow line in the afternoon sun — that single factor is what makes a new floor look restless.

The length: boards laid along the room's longest dimension make the room look longer and calmer, because there are fewer cross-joints per square metre. Laid across, the room looks wider — a valid choice in a very long, narrow hallway where you want to dampen the tunnel effect.

When the two rules disagree — the window sits on the long wall, so the light comes in across the room — the light generally wins in a room with plenty of daylight and large windows, and the length wins in a room with little daylight. If in doubt, lay a few loose boards on the floor both ways on a sunny day and look.

Diagonal and herringbone: when direction becomes a pattern

Diagonal laying (45° to the walls) is typically used to hide the fact that a room is out of square: when the boards are not parallel to any wall, the eye does not notice that the walls are not parallel to each other. The cost is waste — reckon on 10–15% against 5–10% for a straight lay.

Herringbone and chevron do not have a "direction" in the same way, but the pattern has an axis, and you have to choose that axis. The main rule is that the pattern's centre axis follows the room's longest dimension, or the main sightline on entering the room. Herringbone costs 15–20% waste, and the pattern must be set out from the centre of the room, not from a wall — otherwise you end up with half a fish shape in one corner.

The practical details direction affects

• Expansion gap along the walls: a floating floor typically needs 8–12 mm of clearance to any fixed building element, regardless of direction. The gap is covered by the skirting. Large rooms may need an extra movement joint — the supplier's instructions state at what room size.
• Offsetting end joints: end joints in neighbouring rows should typically be offset by at least 30–50 cm, otherwise the pattern looks restless and the joint is weak. That figure is in the laying instructions and takes precedence over the rule of thumb.
• Last row: work out beforehand how wide the last row will be. If it comes out under 5 cm, trim a little off the first row instead, so the first and last rows end up equally wide. That sum depends directly on the direction: 3.05 m ÷ 19 cm board width = 16.05 rows, meaning a last row of only 1 cm — completely unacceptable. Trim 9 cm off the first row instead, so both first and last come out at about 10 cm.
• Underfloor heating: direction has no effect on heat output, but the floor type and thickness do. Follow the supplier's instructions for maximum floor temperature and permitted thermal resistance.

In short

If the boards have to carry load, they run across the joists — that settles it. If the floor is floating, choose the direction based on the longest unbroken axis in the home and on the light from the main window, and keep the same direction through connected rooms. Diagonal laying hides out-of-square walls and costs 10–15% waste; herringbone costs 15–20% and is set out from the centre of the room. And whatever the direction: the supplier's laying instructions take precedence over every rule of thumb, here as everywhere else.