USG's Durock Cement Board.

USG’s mold-resistant Durock Cement Board substrate, which is made from Portland cement that is sandwiched between layers of inorganic fiberglass mat, was developed to provide a water-resistant base for tiled surfaces installed in wet areas.

The product will not swell, soften, decay, delaminate, or disintegrate when exposed to water, USG says. The ½-inch-thick standard cement board panels were designed to work with bathtub and shower surrounds, walls, ceilings, and floors. The boards are also offered in 5/16-inch thickness for use with countertops. Available warranties extend for as long as 30 years and typically cover the replacement of all affected components in the installation, from the substrate to the tile and grout, as well as labor costs.