You install tile backer (also known as backer board) under tile in wet areas because tile needs a good, solid base or substrate. But not just any type of material will work as a substrate.
Cementitious vs. Organic:
What about wood or green board as a base? These materials do not work because you need a cementitious base–one that has the qualities of cement and masonry, cousins of tile.
Wood, regular drywall, and even green board have organic elements which will degrade in high-moisture environments.
Troweled On Base vs. Sheets:
Cementitious tile base is nothing new. Tile installers for thousands of years have created a thick base of mortar upon which to lay the tile.
Installing a backer board is a substitute for troweling on countless thick layers of mortar as a base. In essence, you are getting your troweled on base–except that all the work as been done for you in a factory and is delivered to you in a nice, compact, and hard form: backer board.
Types of Tile Backer Board
Manufacturer: James Hardie Industries
Composition: Unlike pure cement board, the fiber is almost invisibly integrated into the board, making for cleaner cuts. HardieBacker comes in both 3′ x 5′ and 4′ x 8′ sizes. But unless you are installing as a team, you will find the large size too heavy to handle on your own. HardieBacker is 90% Portland cement and sand, along with patented MoldBlock technology.
Details: If you expect to apply fiber cement board in areas of high water volume (tiling a bathtub, for example), you will want to install a barrier of 4 mm plastic behind the backer board.
Review: For DIY tile installers, HardieBacker reigns supreme. Available at Home Depot, HardieBacker’s 1″ x 1″ grid make measuring easy and cutting a snap (literally).
Composition: This glass mat is up to 5% continuous filament glass fiber along with gypsum–the main ingredient in drywall.
Details: DensShield is denser than even HardiBacker. Glass mat is waterproof, eliminating the need for a plastic barrier. The DensShield product also claims to be mold resistant.
Review: If you are comfortable working with drywall, this product is for you. DensShield scores and snaps with a standard utility knife.
Manufacturer: Custom Building Products
Composition: Wonderboard is a very fibrous material, its cement core heavily interlaced with long fibers designed to help hold the board together.
Details: Available in 36″ x 60″ sizes (either 7/16″ or 1/4″ thick), Wonderboard can be cut with a utility knife.
Review: I find Wonderboard difficult to work with, as it tends to crumble easily and needs to be treated gingerly. Screws do not grab very well, tending to pull straight through. On the good side, Wonderboard is cheaper than HardieBacker, so will be more cost-effective with large installations.
wedi Building Panels are so much more than a simple tile backer board and offer endless installation opportunities. Available in a wide variety of thicknesses and sizes, they are compatible with virtually any substructure. wedi Building Panels are lightweight, internally waterproof and dimensionally stable, making them fast, clean and simple to work with. The blue waterproof core is CFC-free, made from waterproof extruded polystyrene foam, reinforced with fiberglass mesh on both sides and coated with synthetic polymer resin mortar which fully embeds the mesh layer resulting in the panel’s strength and the ability to develop highest adhesion strength to virtually any type of thinset mortar. The embedded mesh eliminates the risk of delamination of installation layers.
The wedi Building Panel combines the benefits of the latest manufacturing technology and material quality with sound and traditional benefits our trades enjoy. wedi Building Panels are waterproof, lightweight, easy and clean to cut and still incredibly strong and bond friendly for use with any type of thinset mortar application. The wedi Building Panel can be tiled with all types of ceramic, glass or stone tile whether they are mosaic or large format tiles. Especially large and thin tile benefits of the durability of the wedi Building Panel and the even surface it provides.
Avaliable in these sizes:
Schluter®-KERDI-BOARD is a multifunctional tile substrate and building panel, which can also be used for creating bonded waterproofing assemblies with tile coverings. It consists of an extruded polystyrene foam panel, with a special reinforcement material on both sides and fleece webbing for effective anchoring in thin-set mortar.
With the available panel thicknesses of 3/16″, 3/8″, 1/2″, 5/8″, 3/4″, 1″, 1-1/2″, and 2″ (5, 9, 12.5, 15, 19, 25, 38, and 50 mm), KERDI-BOARD allows the installer to prepare and create a broad range of substrates and building elements for the installation of ceramic and natural stone tile that are flat, level, plumb, square, and dimensionally stable. With suitable preparation of the abutting seams and joint areas, the panel may be used for bonded waterproofing assemblies.
The boards are simply cut to size with a utility knife. The gridlines, which are printed on the surface, are helpful for neat and quick cuts and installation. Tiles can be installed directly over KERDI-BOARD using the thin-set method.