a composite fabric for use in reinforcement of cementitious boards and similar prefabricated building wall panels . the fabric includes an open mesh first component of continuously coated , high modulus of elasticity strands and a nonwoven second component fabricated from alkali resistant thermoplastic material . the high modulus strands of the first component are preferably bundled glass fibers encapsulated by alkali and water resistant thermoplastic material . the composite fabric also has suitable physical characteristics for embedment within the cement matrix of the panels or boards closely adjacent the opposed faces thereof . the reinforcement provides long - lasting , high strength tensile reinforcement and impact resistance for the panels or boards . the reinforcement also enables the boards to have smooth outer faces suitable for painting , papering , tiling or other finishing treatment . included as part of the invention are methods for making the reinforcement , cementitious boards and panels including the reinforcement , and methods for manufacturing such boards and panels .