A backer board designed for use on floors, walls, and ceilings in wet or dry areas, this board is applied directly to wood or metal wall studs or over wood subfloors—referred to in ANSI as Cementitious Backer Units (CBU). Ceramic tile can be bonded to it with dry-set, latex/polymer modified portland cement mortar, or epoxy by following the backer board manufacturer’s instructions. It can also be used for glass and stone installations. Complete interior installation and material specifications are contained in ANSI A108.11 and ANSI A118.9 or ASTM C1325.

A backer board conforming to ASTM C1178. Designed for use on floors, walls, and ceilings in wet or dry areas, this board is applied directly to wood or metal wall studs or over wood subfloors. Ceramic tile can be bonded to it with latex/polymer modified portland cement mortar or epoxy by following the backer board manufacturer’s instructions. It can also be used for glass and stone installations.

A backer board conforming to ASTM C1658. Designed for use on walls and ceilings in dry areas. This board is applied directly to wood or metal studs and ceiling framing. Ceramic tile can be bonded to it with dry-set, latex/polymer modified portland cement mortar, organic adhesive, or epoxy by following the manufacturer’s instructions. It can also be used for glass and stone installations.

A dispersed fiber-reinforced cement backer board designed for use on floors, walls, and ceilings in wet or dry areas, this board is applied directly to wood or metal wall studs or over wood subfloors. Ceramic tile can be bonded to it with latex/polymer modified portland cement mortar, organic adhesive, or epoxy by following the backer board manufacturer’s instructions. It can also be used for glass and stone installations. General interior installation and material specifications are contained in ANSI A108.11 and ASTM C1288. Consult the manufacturer’s written literature for specific application details.

A waterproof backer board constructed from extruded polystyrene and coated with a cementitious coating, designed as a substrate for ceramic tile and stone in wet and dry areas. Designed for use on floors, walls, and ceilings in dry or wet areas, this board is applied directly to wood or metal wall studs or over wood subfloors. Ceramic tile can be bonded to it with dryset, latex/polymer modified portland cement mortar, or epoxy by following the backer board manufacturer’s instructions. It can also be used for glass and stone installations. Material specifications are contained in ASTM C578 and ASTM D4068.

Wood-based panels such as particle board, composite panels (veneer faces bonded to reconstituted wood cores), nonveneer panels (wafer board, oriented strand board, and other similar boards), lauan plywood, and softwood plywood expand and contract with changes in moisture content and are not recommended as backing materials for direct bonding of ceramic tile. Plywood manufactured with fully waterproof adhesive and with an exposure durability rating of Exposure 1 or Exterior may be used on residential horizontal surfaces when installed in accordance with ANSI Specifications for the Installation of Ceramic Tile (A108.01-3.4).

Gypsum wall board (Dry Wall), including water-resistant gypsum backing board, may not be used as a backing for direct application of tile in intermittent wet or wet areas.