Hardie Backer 0.42 in. Cement Board is a cement backerboard designed for use with walls, floors and countertops. Use on walls in moisture prone areas, as a tile backerboard and as an underlayment for all tile, vinyl and wood flooring applications. Provides excellent adhesion, resists moisture and features MoldBlock Technology to protect the board against damage from mold. 0.42 in. thickness provides strength and ease of use on walls, with flooring or countertop projects in bathrooms, kitchens and laundry rooms.