Method of forming a reinforcement sheet to reinforce a cementitious board

1. A method of making a reinforcement sheet for a cementitious board comprising:

applying a hydrophilic coating material on binder coated glass fibers wherein the non-interlaced glass fibers are accumulated in random or selected orientations and are coated with a binder that adheres the glass fibers together by curing prior to applying the hydrophilic coating material on the binder coated glass fibers, the hydrophilic coating material being mobile in slurry water to dilute and disperse upon contact by surface molecules of the slurry water at a surface of a slurry of a cementitious compound to dilute and disperse, and to wet and spread the slurry on the binder coated glass fibers, and the hydrophilic coating material being volatile to dissipate by evaporation at an elevated temperature at which the cementitious compound is dried for the binder coated glass fibers to be essentially free of the hydrophilic coating material as a source of water and moisture absorption to provide a water vapor porous layer with a hydrophobic surface.

2. The method of claim 1 , comprising:

attaching the water vapor porous layer of the binder coated glass fibers to a mesh of glass fibers for imbedding in the slurry.

3. The method of claim 1 , wherein the hydrophilic coating material is nonvolatile at atmospheric temperatures and pressures.

4. The method of claim 1 , wherein the water vapor porous layer is porous to a volatile form of the hydrophilic coating material.

5. The method of claim 1 , wherein the water vapor porous layer has pores for passage of the slurry.

6. The method of claim 1 , wherein the water vapor porous layer has pores preventing passage of the slurry.

7. The method of claim 1 , wherein the glass fibers of the water vapor porous layer are wet-laid.