Cementitious exterior sheathing products are provided which include a rigid support member affixed to a cementitious layer. The rigid support member includes at least one nailing flange disposed along one of its lateral sides for allowing the sheathing product to be affixed to an exterior wall of a building. Preferred mechanical and adhesive bonding techniques are suggested for combining the cementitious layer and rigid support member together to form an integrated product. Such products are lighter in weight and are more crack resistant than currently available fiber cement trim boards.