Manufacturers of underlayment for ceramic tile include Durock, WonderBoard, HardieBacker, Fiberock and DensShield. Durock and WonderBoard make concrete backerboard underlayment, while HardieBacker and Fiberock make underlayment out of fiber cement. DensShield makes underlayment out of water-resistant gypsum.
HOMETIME considers concrete backerboard the standard material for ceramic tile underlayment. Concrete backerboard features a solid concrete core bound on both sides by fiberglass, forming a watertight seal that is ideal for kitchens and bathrooms. Cutting backerboard underlayments is similar to cutting drywall, except that the reinforced underlayment material is denser and harder than drywall.
In order to install an underlayment for ceramic tiles, homeowners must use the same type of thinset mortar used to set the tiles, and then reinforce the sheets with galvanized nails or backerboard screws securing the backerboard to the floor. Professional contractors often put down a bed of mortar that consists of a layer of roofing felt, a layer of wire mesh and a layer of thinset mortar to ensure optimal results and water resistance. HOMETIME, however, suggests that a properly installed underlayment provides reasonable performance; the site even claims that a stable concrete slab can be a great ceramic tile underlayment if the floor beneath it is completely flat.