A coated glass mat comprises a glass mat substrate having non-woven glass fibers and a coating which essentially uniformly penetrates the glass mat substrate to desired fractional thickness of the coated glass mat. The coating imparts a tensile strength to the coated glass mat which on average is at least 1.33 times greater than the tensile strength of the glass mat substrate without the coating. In example embodiments, penetration of the coating into the glass mat substrate preferably extends to a depth of from twenty five percent of a thickness of the coated glass mat to seventy five percent of the thickness of the coated glass mat. Moreover, a non-coated thickness of the coated glass mat is sufficiently thick for bonding purposes with, e.g., a gypsum slurry or other core materials such as thermoplastic or thermosetting plastics. The coating has a porosity in a range of from 1.3 CFM to 5.0 CFM, e.g., the coating comprises a coating blend which provides the coated glass mat with a porosity sufficient to allow water vapor to escape from a gypsum slurry when heated. The coating is preferably a coating blend comprised of water, latex binder, inorganic pigment, and inorganic binder.