A drier for drying a board, the board having two principal surfaces that are opposed to each other, the drier comprising: rollers (30a, 30b) for conveying the board along a longitudinal direction of the drier, the rollers further being for supporting the board in a support plane containing the longitudinal direction of the drier; air inflow means for directing airflow towards the principal surfaces of the board, the air inflow means comprising a lower conduit and a upper conduit, the lower and upper conduits each having a substantially rectangular cross-section and a planar face facing towards the support plane and each extending transversely to the longitudinal direction of the drier, the lower conduit having a plurality of apertures (36, 38) for directing airflow towards an underside of the board and the upper conduit having a plurality of apertures (42,44) for directing airflow towards an upper side of the board; wherein the combined cross-sectional area of the upper and lower conduits at their respective airflow inlets is at least 40% of the unit area of the drier, the unit area being a quadrilateral having: one side equal to the distance between the axis of the roller immediately preceding the lower conduit, in the direction of travel of the board, and the axis of the roller immediately following the lower conduit, in the direction of travel of the board; and another side equal to the distance between the uppermost portion of the upper conduit and the lowermost portion of the lower conduit; and further wherein the width of the lower conduit in the longitudinal direction of the drier is less than the width of the upper conduit in the longitudinal direction of the drier. rollers (30a, 30b) for conveying the board along a longitudinal direction of the drier, the rollers further being for supporting the board in a support plane containing the longitudinal direction of the drier; air inflow means for directing airflow towards the principal surfaces of the board, the air inflow means comprising a lower conduit and a upper conduit, the lower and upper conduits each having a substantially rectangular cross-section and a planar face facing towards the support plane and each extending transversely to the longitudinal direction of the drier, the lower conduit having a plurality of apertures (36, 38) for directing airflow towards an underside of the board and the upper conduit having a plurality of apertures (42,44) for directing airflow towards an upper side of the board; wherein the combined cross-sectional area of the upper and lower conduits at their respective airflow inlets is at least 40% of the unit area of the drier, the unit area being a quadrilateral having: one side equal to the distance between the axis of the roller immediately preceding the lower conduit, in the direction of travel of the board, and the axis of the roller immediately following the lower conduit, in the direction of travel of the board; and another side equal to the distance between the uppermost portion of the upper conduit and the lowermost portion of the lower conduit; and further wherein the width of the lower conduit in the longitudinal direction of the drier is less than the width of the upper conduit in the longitudinal direction of the drier. one side equal to the distance between the axis of the roller immediately preceding the lower conduit, in the direction of travel of the board, and the axis of the roller immediately following the lower conduit, in the direction of travel of the board; and another side equal to the distance between the uppermost portion of the upper conduit and the lowermost portion of the lower conduit; and further wherein the width of the lower conduit in the longitudinal direction of the drier is less than the width of the upper conduit in the longitudinal direction of the drier.