Abstract: New and useful cementitious-based products, such as mortar, grout, backerboard and stucco, are all comprised of Portland cement as a common ingredient combined with optional fillers and additives with the addition of an effective antimicrobial agent. In a humid, warm and a poorly circulating air environment, mildew from a fungus, as well as the growth of other microbes will flourish. With the addition of Copper-8-quinolinolate as a fungicide to the cementitious-based mix, a zone of antibiosis is created to inhibit the growth of these organisms for the duration of the products use.