A bond is created between a gypsum matrix formed from an aqueous acidic gypsum slurry comprising a monomer mixture. The monomer mixture is composed of a monomer having acidic functionality and a monomer having hydroxyl or amine functionality. A silane-based sizing composition is coated onto glass fibers causing a cross-linking network of silane and monomer mixture to form during curing of the gypsum board. Hydrophilic water extraction at the gypsum matrix-sizing interface reduces void formation and promotes bonding with the crosslinked monomer mixture and growth of smaller gypsum crystals within larger crystals in microstructurally identifiable regions adjacent to the glass fiber. A bond is created between a gypsum matrix formed from an aqueous acidic gypsum slurry comprising a monomer mixture. The monomer mixture is composed of a monomer having acidic functionality and a monomer having hydroxyl or amine functionality. A silane-based sizing composition is coated onto glass fibers causing a cross-linking network of silane and monomer mixture to form during curing of the gypsum board. Hydrophilic water extraction at the gypsum matrix-sizing interface reduces void formation and promotes bonding with the crosslinked monomer mixture and growth of smaller gypsum crystals within larger crystals in microstructurally identifiable regions adjacent to the glass fiber. Alternatively, the silane based sizing composition has branched chains that diffuse into a wet gypsum mix containing the monomer mixture. During gypsum cure, the diffusion and crosslinking of monomer mixture triggers formation of interpenetrating pseudo polymeric networks within a microstructurally identifiable region adjacent to the glass fiber. Bonds formed between the gypsum matrix and the silane based sizing composition increase the strength, flexure resistance and nail pull out resistance of the gypsum board.