Wood floors with single-face (not multi-strip) plank widths of 155mm (6") or more are considered to be wide plank.

Today’s heating and cooling systems, when combined with seasonal fluctuations, subject wood floors to quite extreme temperature and humidity changes. When subjected to these changes, wide plank, non-engineered solid wood floors tend to show deficiencies: they can gap between the planks, cup across their width and warp along their length.
In certain cases where the solid wood has moved too much, the floor will fail, i.e. lift away from the sub-floor. To overcome these tendencies wide plank wood floors must be uncompromisingly engineered.

Exceptionally engineered wide plank wood floors
The wood engineering technique used in the construction of an Element 7 wide plank sets a
world-class standard. Planks are available up to phenomenal 340mm widths and 5m lengths.