The invention provides a board forming system comprising a forming table comprising a belt with a surface for conveying a backing layer; a mixer fitted with a mechanism capable of depositing cementitious slurry material over a top surface of the backing layer; and a slurry spreader positioned downstream of the mixer, wherein a portion of the slurry spreader comprises a plurality of apertures which are connected to a source of pressurized fluid. The slurry spreader is configured such that the pressurized fluid flows out of the slurry spreader through the apertures so as to provide a continuous film of fluid across an outer surface of the slurry spreader. The slurry spreader is positioned such that it can contact at least a portion of the cementitious slurry after the slurry exits the discharge and before the slurry is spread across the width of the backing layer such that the thickness of the slurry is approximately equal to the desired slurry thickness for board formation. The invention further provides methods for forming cementitious board comprising the use of the slurry spreader.