2024-25_NTCA_Reference_Manual_dig_dwnld

Backer Board Definitions

Cement Backer Board A backer board designed for use on floors, walls, and ceilings in wet or dry areas, this board is applied directly to wood or met al wall studs or over wood subfloors – referred to in ASTM and ANSI as Cementitious Backer Units (CBU). Ceramic tile can be bonded to it with dry-set cement mortar, modified dry-set ce ment mortar, organic adhesive, or epoxy by following the backer board manufacturer’s instructions and the applicable method specified. 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. Fiber-Cement Backer Board 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 sub floors – referred to in ASTM as fiber-cement interior substrate sheets. Ceramic tile can be bonded to it with modified dry-set cement mortar, improved modified dry-set cement mortar, or ganic adhesive, or epoxy by following the backer board manu facturer’s instructions and the applicable method specified. It can also be used for glass and stone installations. General in terior installation and material specifications are contained in ANSI A108.11 and ASTM C1288. Consult the manufacturer’s writ ten literature for specific application details. Gypsum Board A backer board conforming to ASTM C1396. Designed for use in dry areas, this board is applied directly to wood or metal studs and ceiling framing. Ceramic tile can be bonded to it with mod ified dry-set cement mortar, improved modified dry-set cement mortar, organic adhesive, or epoxy by following the manufac turer's instructions and the applicable method specified. It can also be used for glass and stone installations. Coated Glass Mat Water-Resistant Gypsum Panel 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 sub floors. Ceramic tile can be bonded to it with modified dry-set ce ment mortar, improved modified dry-set cement mortar, or ep oxy by following the backer board manufacturer’s instructions. It can also be used for glass and stone installations. Glass Mat Gypsum Panels A backer board conforming to ASTM C1658. Designed for use on walls and ceilings in limited water exposure and dry areas, this board is applied directly to wood or metal studs and ceiling framing. Ceramic tile can be bonded to it with dry-cement mor tar, modified dry-set cement mortar, improved modified dry set cement mortar, organic adhesive, or epoxy by following the manufacturer’s instructions and applicable methods specified. It can also be used for glass and stone installations.

Fiber-Reinforced Gypsum Panel A backer board conforming to ASTM C1278. Designed for use on floors, walls, and ceilings in dry or limited water exposure areas and is applied directly to wood or metal wall studs or over wood subfloors. Ceramic tile can be bonded to it with dry-cement mortar, modified dry-set cement mortar, improved modified dry-set cement mortar, organic adhesive, or epoxy by following the backer board manufacturer’s instructions and applicable method specified. It can also be used for glass and stone in stallations. Cementitious Coated Extruded Foam Backer Board A waterproof backer board constructed from extruded poly styrene 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 ar eas, this board is applied directly to wood or metal wall studs or over wood subfloors. Ceramic tile can be bonded to it with dry-cement mortar, modified dry-set cement mortar, improved modified dry-set cement mortar, organic adhesive, or epoxy by following the backer board manufacturer’s instructions and applicable method specified. It can also be used for glass and stone installations. Material specifications are contained in ASTM C578 and ASTM D4068. Direct Bond to Wood or Gypsum Wall Board – Caution Wood-based panels such as particle board, composite panels (veneer faces bonded to reconstituted wood cores), nonveneer panels (wafer board, oriented strand board [OSB], and other similar boards), luan plywood, and softwood plywood expand and contract with changes in moisture content and are not rec ommended 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 ac cordance with ANSI specifications for the installation of ceram ic tile (A108.12). Gypsum board, including water-resistant gypsum backing board, may not be used as a backing for direct application of tile in intermittent wet or wet areas.

Chapter 3 | Backerboards and Underlayments Source: “Backer Board Selection Guide,” in TCNA Handbook for Ceramic, Glass, and Stone Tile Installation , pp. 21-22. © 2024 Tile Council of North America. Reprinted by permission. 84

NTCA Reference Manual | 2024 / 2025