Tile backer board reduces the need for creating a thick bed of wet mortar under your tile. Available at most home centers, tile backer board is, in essence, a mortar bed that has been created in a factory, dried, and shipped in predictable sizes and thicknesses.
Tile Backer Board Basics
Tile needs a rock-solid base, or substrate, to last for years without cracking. Not just any type of material will work as a substrate, though. Ordinary milled wood, regular drywall, and even water-resistant drywall contain organic elements which will degrade in high-moisture environments. The only building material derived from organic elements that does work is plywood, and this is chiefly because of plywood’s cross-hatched layers which keep it dimensionally stable. A better route is to go with a cementitious tile base, one that has the qualities of cement and masonry. Tile installers have traditionally created thick beds of wet mortar as a base for tile; it is a practice that extends back to the Roman Empire. Installing a tile backer board is a substitute for troweling on these thick layers of mortar as a base. In essence, you are getting your troweled-on base, except most of the work has been done for you in a factory. Pre-formed tile backer boards not only eliminate the work and mess of wet mortar beds, they vastly speed up the process of tile installation because there is no need to wait for a thick bed of mortar to dry.
Tile Backer Board Dimensions
Tile backer board tends to come in a limited number of sizes on the consumer market. Generally, expect to find backer boards at your local home center that are 3 feet wide by 5 feet long. It is possible to find backer boards that are 4 feet wide by 8 feet long. Since these larger format backer boards can weigh in excess of 75 pounds and have sharp edges, handle only with gloves and with assistance from a partner. Since tile backer board easily seams with mesh tape and a quick swipe of thinset, most do-it-yourselfers will have little need for large backer boards. The most common thickness of tile backer board is 1/2-inch. Quarter-inch and 5/8-inch thicknesses can also be found. Use 1/4-inch backer board on curved applications or on vertical surfaces such as fireplaces. Use 5/8-inch backer board as a fire-rated material similar to Type X drywall.
Tile Backer Board Brands
HardieBacker
James Hardie Industries manufactures HardieBacker. Unlike pure cement board, HardieBacker’s fiber is almost invisibly integrated into the board, making for cleaner cuts. HardieBacker is composed of 90-percent Portland cement and sand, along with James Hardie Industries’ patented MoldBlock technology. If you expect to apply fiber cement board in areas of high water volume, such as inside of a bathtub or swimming pool, it is recommended that you install a barrier of 4 mil plastic behind the backer board. For do-it-yourself tile installers, HardieBacker is easy to use, as its 1-inch by 1-inch grid makes measuring simple.
DensShield
Georgia-Pacific makes DensShield, a cement-glass mat that is up to 5-percent continuous filament glass fiber mixed in with gypsum. DensShield is denser than HardieBacker. DensShield is waterproof, eliminating the need for a plastic barrier, plus it is mold resistant. This makes DensShield a good tile backer for those high-moisture applications: no plastic barrier necessary. If you are comfortable working with drywall, you may find DensShield to be the perfect product for you as it easily scores and snaps with a standard utility knife.
Wonderboard
Custom Building Products manufactures the tile backer board called Wonderboard. Wonderboard is a fibrous material, its cement core heavily interlaced with long fiberglass fibers designed to help hold the board together. Wonderboard can be cut with a utility knife or with a low-speed power tool such as a jigsaw. Wonderboard tends to crumble easily and should be treated gingerly. Wonderboard is often less expensive than HardieBacker, making it more cost-effective for large installations such as whole-house floor tile projects.
