A bond is created between gypsum crystals and between gypsum crystals and glass fiber reinforcement in a gypsum board during cure by incorporation of titanium or zirconium based coupling compositions incorporated in the gypsum slurry. The commercially available titanium or zirconium based coupling has a generic formula of the type [RO--}-nTi-[--OXR'Y]4-n or [RO--}-nZr-[--OXR'Y]4-n. These coupling compositions chemically bond to glass fibers by replacing the --OH groups present on the glass fibers in aqueous solutions with Ti--O or Zr--O bonds. The X functionality of the coupling composition is selected to be a phosphato or pyrophosphato group to form bond with calcium ions of the gypsum crystal. The bond created by the titanium or zirconium based coupling composition results in load transfer between gypsum crystals in the gypsum matrix and between the glass fibers and gypsum matrix, resulting in improved flexure strength and nail pullout resistance.