1. There are a variety of backer board options available for tile installation, including traditional fiberglass-reinforced cement boards and innovative products that incorporate recycled materials. 2. Backer boards come in different thicknesses and dimensions to provide a stable surface for tile in floors, walls, and countertops. They also offer options for wet or dry areas. 3. Newer backer boards have lightweight foam cores with fiberglass mesh and cement coatings, making them easier to handle while maintaining strength and affordability. Proper board selection depends on the application.

1. Backer Board Unit Choices
CERAMIC TILE INSTITUTE OF AMERICA, INC.
12061 Jefferson Blvd., Culver City, CA 90230-6219
CTC Graduate Field Report
Subject: Backer Board Unit Choices – General Product Information
By
Richard Jacobs CTC
Introduction
Technology is changing everything, even backer boards. Manufacturers are offering a
wide variety of products, from the traditional fiberglass-covered cement boards to
products that incorporate innovative, recycled materials and green building concepts.
Choosing the right backer board for the right job is critical. Backer boards are available
in ¼”, ½” and 5/8” thickness and come in many different dimensions. Because not all
surfaces are perfectly flat, these products can provide a more stable surface for the
application of tile and stone products. Whether one is installing backer board for floors,
walls or counter tops, the craftsman has many product application decisions to
consider. There are a number of different products available for application in wet or
dry areas in relation to a water-resistant or waterproof backer board.
The introduction of light-weight backer boards with a foam core that is covered in
fiberglass mesh and cement coating have created new options since the original solid
cement core products. Light-weight backer boards are less cumbersome and have
greatly reduced weight loads for easy handling in the field. Backer boards have an
advantage in that they have low mass, are quick to install and relatively inexpensive,
while providing a good base for stone and tile areas that transition with existing floor
and wall covers.
Industry Trade Association and Recommendations

2. The format for this report is based on the categories within the 2005 TCA handbook
and the1999 American National Standards Institute, a publication for the compilation
of voluntary standards for the installation of ceramic tile.
The Tile Council of North America (TCA) handbook/conference acknowledged other
backer units that are on the market for use as a backing and underlayment with ceramic
tile. However, the conferees felt there was insufficient experience and test data
available to consider specific comment as to their use. In these cases, follow the
manufacturer’s recommendations.
Products and Trade Applications
ANSI A108.11- A118.9-1999 Interior installation of cementitious backer units and
American national standards for test methods and specifications for cementitious
backer units.
ANSI A108.11 / ANSI A-4.8 These voluntary standards define the interior installation,
test methods and physical properties of cementitious backer units (CBU’s) as a
substrate for the installation of ceramic tile. They are intended to serve as a guide to the
general public, manufacturer’s, architects, installing mechanics, testing laboratories,
and other businesses and professionals in producing, specifying, installing and testing
cementitious backer units.
ANSI A118.9 / L-2.1 Cementitious backer unit (CBU) – A nailable/screwable backer
board or underlayment panel which is composed of stable Portland cement, aggregates,
and reinforcements that have a significant ability to remain unaffected by prolonged
exposure to moisture.
Cementitious Backer Unit (CBU)
1. TCA Reference
A backing and underlayment designed for use on floors, walls, and ceilings in
wet and dry areas, this board is applied directly to wood or metal wall studs or
over wood subfloors. Ceramic tiles can be bonded to it with dry-set,
latex/polymer modified Portland cement mortar, or epoxy by following the
manufacturer’s instructions. Complete interior installation and material
specifications are contained in ANSI A108.11 and A118.9 or ASTM C1325.
2. General Product Description
The name cement is derived from the Latin word caementum meaning rough
stone. Cement manufacturing involves a mix of raw materials, typically about
85% limestone or similar rocks like marble or marl, with the rest mainly clay or
shale. This mixture is heated until it nearly melts and is then ground into a
powder. When cement is mixed with water, it creates a paste. When the paste is
mixed with aggregates, the paste binds them all together because a chemical
reaction occurs, called hydration. The crystals radiate outward from the cement
grains and mesh with other adjacent crystals or adhere to the aggregates,
creating the finished product.

3. 3. TCA detailed drawings for this product can be referenced as follows, B412-05,
B415-05, C315-05, C513-05, F144-05, RH135-05, RW800-05, SR614-05,
TR420-05, and W244-05.
Coated Glass Mat Water-Resistant Gypsum BackerBoard:
1. TCA Reference
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 dry-
set, latex/polymer modified Portland cement mortar, organic adhesive, or
epoxy.
2. General Product Description
The mineral name gypsum is derived from the Greek word gypsos, which
means plaster. Originally it referred to the type of gypsum which was heated to
a high temperature to drive off water, the water in its crystal structure; this is
called calcined gypsum. Gypsum belongs to a group of minerals called sulfates,
and is the most common of the approximately 150 sulfate minerals. Sulfates are
compounds of one or more metals with oxygen and sulfur. The oxygen and
sulfur join together to form the sulfate ion, gypsum. Only a 2 rating on the
Moh’s hardness scale, gypsum is a very soft mineral.
3. TCA detailed drawings for this product can be referenced as follows: B419-05,
B420-05, C311-05, C315-05, C513-05, F146-05, RH135-05, and W245-05.
Fiber-Cement Underlayments
1. TCA Reference
A dispersed fiber-reinforced cement backer and underlayment 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. General
interior installation and material specifications are contained in ANSI A108.11
and ASTM C 1288.
2. General Product Description
Fiber-reinforced cement backer board is a product produced by composite
materials consisting of Portland cement, fine aggregates, water, alkali-resistant
glass fibers and additives which, when mixed in exact proportions, achieve
construction–grade physical properties that allow it to be used for numerous
applications, especially those where weight is a significant factor in design.
3. TCA detailed drawings for this product can be referenced as follows: B412-05,
B415-05, C513-05, F144-05, RH135-05, RW800-05, TR420-05, W223-05, and
W244-05.
Fiber-Reinforced Water-Resistant Gypsum Backer Board/Underlayment:

4. 1. TCA Reference
A backer board/underlayment conforming to ASTM. Designed for use on
floors, walls, and ceilings in dry or limited water exposure 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.
2. General Product Description
Because gypsum was discussed in the preceding category and that reference
can be used for the core of this product, this paragraph will be dedicated to the
minerals of glass and fiberglass properties. Once again we find that fiber
additives incorporated into these backer board products originate from natural
minerals.
a. Soda Ash is anhydrous sodium carbonate. It is made by the processing of the
minerals Trona and Nahcolite with sodium carbonate-rich waters, called brines.
b. Feldspar is the mineral distinguished by the presence of aluminum and the
silica ion in their chemistry. This group includes aluminum silicates of soda,
potassium and lime.
Industrial sand, gravel, soda ash and feldspar are mixed together, incorporated
in the proper manufacturing process and create glass fibers. Most, if not all
backer boards use a glass mat or fiber mesh.
3. TCA detailed drawings for this product can be referenced as follows: B430-
05, C315-05, C513-05, F170-05, RH135-05, RW800-05, W223-05, W247-05.
Cementitious Coated Foam Boards
1. TCA Reference
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 dry-set, latex/polymer modified
Portland cement mortar, or epoxy by following the manufacturer’s instructions.
Material specifications are contained in ASTM C578, Minimum TypeV1 and
ASTM D4068-01 (Annex2).
2. General Product Description
Extruded polystyrene is closed-cell foam. The production of extruded foam
starts with solid resin pellets. The pellets are fed into an extruder where they are
melted and mixed with other materials. Then, a blowing agent is injected to
make the mixture foamable. Under controlled heat and pressure conditions, the
foamable mixture is forced through a die, at which time a shaping occurs and a

5. finished foam product is produced. Foam densities can vary depending on the
amount of pressure provided during the manufacturing process. The continuous
extrusion process produces a uniform, closed-cell structure that makes extruded
polystyrene highly resistant to moisture intrusion and yields reliable
compressive strength durability. Polystyrene is a thermoplastic material which
means it is recyclable.
3. TCA detailed drawings for this product can be referenced as follows, B425-05,
B426-05, C315-05, F175-05, and W246-05.
Conclusion
The building products incorporated in this report originate from earth minerals and
have low impact on our ecological environment or are sustained within the recycled
manufacturing process. New technologies and by-product applications are producing
many new materials that qualify for green building concepts. The new technologies are
greatly improving the backer board industry. The choice of products and their specific
applications will require the responsibility of the craftsman to maintain current product
knowledge and up to-date application techniques. It has become very obvious in
today’s world that every product application is unique and must be researched from all
governing code authorities and manufacturers’ suggested installation procedure.
Reference Materials:
ANSI, For the installation of Ceramic Tile 1999
TCA, Handbook for Ceramic Tile 2005
PCA, Portland Cement Association
Mineral Information Institute
Extruded Polystyrene Foam Association
The preceding article was researched and written by Richard Jacobs, CTC, a graduate
of the CTIOA Inc.
Ceramic Tile Consultant Course. The report was reviewed and approved by the CTIOA
Inc. Technical Committee.