HardieBacker® cement board is a tile underlayment made to use on walls, with floors and countertops. Works as a tile backerboard and as an underlayment for tile, vinyl and wood flooring. .42" cement board is made of 90% Portland cement and sand, resists damage from moisture and provides excellent tile adhesion. Product formulation results in a combination of strength, uniform composition and performance. HardieBacker® cement board is easier to use, cuts with tight seam lines and less debris. HardieBacker® contains superior strength and durability delivering a solid foundation on walls, with tile, flooring and stone countertops.