What Size Backer Board for Installing Tile Around a Tub?

Type of Tub

• The type of bathtub you are tiling around will help determine what kind of backer board you use for the tile installation. A pre-set tub where the tile installation runs up to and terminates at the edge of the tub has a different set of requirements than a top-mounted tub that actually rests on top of the tile installation around its perimeter. Concrete and fiber boards can withstand the weight drywall boards cannot, but drywall boards can be used for pre-set tubs.

Cement Boards

• Cement boards come in two different thicknesses. While quarter-inch material is the standard for most floors and half-inch is the standard for walls, you can use quarter-inch material over the entire surface of the tub deck if there is already a layer of plywood down. Bare studs, on the other hand, require the half-inch-thick material to make up for the lack of support behind the board.

Waterproof Drywall

• Waterproof drywalls are a half-inch thick and can be installed in any type of tub setting where the tub is pre-set and already installed onto the frame. It installs exactly like drywall and can be cut with a utility knife. After the board is installed, you cover all of the screw holes with silicone as well as fill in the inside corners and the area around the tub so that any eventual water spillage over the lip of the tub won’t damage the wood frame.

Fiber Boards

• Like cement boards, fiber boards can be used in any tub setting, regardless if it is a top-set or pre-set tub. Quarter-inch-thick material is the standard for fiber boards, and they can be installed across the entire surface of the tub frame so long as there is already an existing plywood covering. They cannot be used without some form of plywood underneath them, as they lack the strength to work as an actual substrate and backer.