A process for making fiber reinforced cementitious panels, comprising: using a first formula: S f 1, l P = 4 V f, l t l π 1 + X f d f for determining a projected fiber surface area fraction of a first fiber layer (30, 70) to be deposited in each settable slurry layer (46, 80) of the resulting panel; using a second formula: S f 2, l P = 4 X l V f, l t l π 1 + X f d f for determining a projected fiber surface area fraction of a second fiber layer (68, 84) to be deposited in each settable slurry layer (46, 80) of the resulting panel; providing a desired slurry volume fraction V f of a percentage of the fibers in the fiber-reinforced slurry layer; adjusting at least one of the fiber diameter d f, and a fiber-reinforced slurry layer thickness t l in the range of 1,27 to 8,89 mm (0.05-0.35 inches), and further apportioning the volume fraction V f of fibers into a proportion X f of the supply of fibers comparing the fibers in the second layer to the fibers in the first fiber layer so that the fiber surface area fraction S f 1, l P and the fiber surface area fraction S f 2, l P for each fiber layer is less than 0.65; providing a supply of loose, individual fibers according to the above-calculated fiber surface area fraction S f 1, l P; further comprising: (a) providing a moving web (14, 26); (b) depositing the first layer of loose, individual fibers (30, 70) upon the web (14, 26); (c) depositing a layer of settable slurry (46, 80) upon the first layer of individual, loose fibers (30, 70); (d) depositing the second layer of loose, individual fibers (68, 84) upon the layer of settable slurry; and (e) embedding said loose, individual fibers in said slurry so that said multiple layers of fibers are distributed throughout each said slurry layer in said panel. using a first formula: S f 1, l P = 4 V f, l t l π 1 + X f d f for determining a projected fiber surface area fraction of a first fiber layer (30, 70) to be deposited in each settable slurry layer (46, 80) of the resulting panel; using a second formula: S f 2, l P = 4 X l V f, l t l π 1 + X f d f for determining a projected fiber surface area fraction of a second fiber layer (68, 84) to be deposited in each settable slurry layer (46, 80) of the resulting panel; providing a desired slurry volume fraction V f of a percentage of the fibers in the fiber-reinforced slurry layer; adjusting at least one of the fiber diameter d f, and a fiber-reinforced slurry layer thickness t l in the range of 1,27 to 8,89 mm (0.05-0.35 inches), and further apportioning the volume fraction V f of fibers into a proportion X f of the supply of fibers comparing the fibers in the second layer to the fibers in the first fiber layer so that the fiber surface area fraction S f 1, l P and the fiber surface area fraction S f 2, l P for each fiber layer is less than 0.65; providing a supply of loose, individual fibers according to the above-calculated fiber surface area fraction S f 1, l P; further comprising: (a) providing a moving web (14, 26); (b) depositing the first layer of loose, individual fibers (30, 70) upon the web (14, 26); (c) depositing a layer of settable slurry (46, 80) upon the first layer of individual, loose fibers (30, 70); (d) depositing the second layer of loose, individual fibers (68, 84) upon the layer of settable slurry; and (e) embedding said loose, individual fibers in said slurry so that said multiple layers of fibers are distributed throughout each said slurry layer in said panel. (a) providing a moving web (14, 26); (b) depositing the first layer of loose, individual fibers (30, 70) upon the web (14, 26); (c) depositing a layer of settable slurry (46, 80) upon the first layer of individual, loose fibers (30, 70); (d) depositing the second layer of loose, individual fibers (68, 84) upon the layer of settable slurry; and (e) embedding said loose, individual fibers in said slurry so that said multiple layers of fibers are distributed throughout each said slurry layer in said panel.