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Tile Backer Boards: Cement backer, Drywall, Greenboard, Glass-mat Gypsum
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InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.
Tile backers: cement board, green board, other products: this article discusses the types and installation details for backer boards used below ceramic tiles for countertops and splashboards, including cement backerboard, drywall, greenboard, and glass-mat gypsum backerboards. We address the installation details for each of these material types. Also see flooring basics at Floor Designs: Kitchen & Bathroom and see Floor Tile, Ceramic for K & B.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
Cement Backerboard for Use Under Ceramic Tile: Installation Specifications
This article series discusses current best design practices for kitchens and bathrooms, including layout, clearances, work space, and accessible kitchen and bathroom layout, clearances, turning space, grab bars, controls, etc. We include advice on choosing and installing kitchen countertops, cabinets, and kitchen or bathroom flooring, sinks, and other plumbing fixtures and fixture controls such as faucets. A list of kitchen and bath product manufactures and sources is included. This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.
Developed specifically for use
under ceramic tile, cementitious backer units (CBUs) are
made of sand and cement and are reinforced by fiberglass
facings or chopped fibers within the material itself. Cement
backerboard is impervious to moisture, but may let
moisture pass through, so it should always be backed by
a waterproof barrier, such as polyethylene sheeting or
asphalt-impregnated felt.
[Click any image or table to see an enlarged version with additional detail, commentary & source citation.]
Because the material has little
inherent strength, it relies on the structure beneath for stiffness
when used on floors and other applications subject to
significant loads. A variation on cement backerboard,
Hardibacker (James Hardie Building Products), is made of
fiber-cement. Because it is only 1/4 inch thick, it is usually
installed over 1/4 -inch plywood, both for stiffness and to
bring it flush with the surrounding drywall.
Cement backerboard should be installed with special
backerboard screws (not drywall nails) that have an anti corrosive
coating and oversized heads with ridges underneath
designed to self-countersink and pull tight. Roofing
nails are also acceptable with most backerboards.
Closely follow manufacturers instructions, which vary a
little from product to product. Typical installations include:
- Backerboard on walls: CBUs can go directly over
studs at 16 inches on-center or over drywall, and it is
fastened with 1 1/2 -inch galvanized roofing nails or
special self-countersinking galvanized screws at 6
to 8 inches on-center.
- Backerboard on floors and countertops: CBUs are
bonded to the plywood with a layer of latex- or
acrylic-modified thinset (Figure 6-34 above and Figure 6-35 below).
Apply the thinset with the flat side of a 1/4 -inch notched
trowel, then rake with the notched side to provide a
continuous level setting bed. Seat the backerboard
evenly with a beating block, then secure with roofing
nails or special backerboard screws. Because CBUs
provide little added stiffness, it is best to upgrade to
a 23/32-inch subfloor.
- Joint details for Cement Backerboard Under Tile: Leave a 1/8 - to 3/16-inch gap between
adjoining sheets of backerboard and at edges. Just
before tiling, fill the joints with thinset and cover
with 2-inch-wide fiber mesh tape (unless the adhesive
manufacturer recommends otherwise). Then embed
the tape in a thin skim coat of thinset. Reinforce inside
and outside corners with three pieces of 2-inch tape or
one piece of 4-inch tape.
- Obstruction Clearances at Concrete Backerboards: Leave a minimum 1/4 -inch gap where the
CBU meets a tub lip, plumbing fixture, pipe, or any
restraining surface and fill the joint with a flexible,
waterproof sealant.
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Installation Guide for Drywall Substrate Below Tile
Regular 1/2-inch drywall over 2x4 framing or
steel studs 16 inches on-center is a suitable substrate for
dry installations. Using 5/8-inch drywall or a second layer of 1/2-inch will provide a stiffer wall. Joints should be taped
and one coat of joint compound applied to joints and nails.
If tiles will be set in thinset mortar, use thinset with mesh
tape at the drywall joints.
Using "Greenboard" Moisture-Resistant Drywall Under Tile
 Commonly called
“greenboard,” this offers moderate protection in moist conditions,
but it is not recommended in wet areas, such as tub
surrounds, unless protected by a waterproof membrane.
In our photo the greenboard has been coated with joint compound and sanded - those surfaces were being prepared for painting rather than for tile installation.
Coated Glass-Mat Gypsum Backerboard Use Under Tile
Competing
with cement backerboard, gypsum products such as
Georgia Pacific’s Dens-Shield® are designed as tile substrates
for damp areas. The gypsum core is treated with silicone
to make it water-resistant, and the fiberglass and
acrylic facing acts as a surface vapor barrier.
While not as
strong as cement backerboard, gypsum-based backerboard
installs faster since it cuts and installs like drywall. Installation
is with roofing nails or galvanized bugle-head drywall
screws, which should be driven flush with the surface
but should not break the waterproof skin.
Panels are butted
tightly and the joints are taped and embedded with latex
Portland cement mortar, also used to set the tile.
In use since 1987, Dens-Shield® is well-suited to tub
surrounds and other light-duty wall applications, but it is
not suitable for saunas, steam rooms, or other applications
facing extreme heat and humidity. As with other tile substrates,
follow manufacturer’s instructions closely regarding
framing, installation, and tile application.
Ceramic Tile Backerboard Producers
Custom Building Products
www.custombuildingproducts.com
Wonderboard cement backerboard, Easyboard cement and
polystyrene lightweight backerboard, and Rhinoboard
fiber-cement backerboard
Georgia-Pacific Gypsum
www.gp.com/build
Denshield gypboard backer with glass-matt facing
James Hardie Building Products
www.jameshardie.com
Fiber-cement backerboard
National Gypsum
www.nationalgypsum.com
Permabase lightweight cement and polystyrene
backerboard
Schluter Systems
www.schluter.com
Kerdi tile membrane goes directly over drywall or other
substrates
T. Clear Corp./Fin Pan Inc.
www.finpan.com
Util-A-Crete lightweight concrete backerboard
U.S. Gypsum
www.usg.com
Durock cement backerboard
W. R. Bonsal
www.bonsal.com
Extruded polystyrene backerboard with fiberglassreinforced
cement facing
-- Adapted with permission from Best Practices Guide to Residential Construction.
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
 The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.
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- The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.
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- "The Elimination of Unsafe Guardrails, a Progress Report," Elliott O. Stephenson, Building Standards, March-April 1993
- "Are Functional Handrails Within Our Grasp" Jake Pauls, Building Standards, January-February 1991
- Access Ramp building codes:
- UBC 1003.3.4.3
- BOCA 1016.3
- ADA 4.8.2
- IBC 1010.2
- Access Ramp Standards:
- ADA (Americans with Disabilities Act), Public Law 101-336. 7/26/90 is very often cited by other sources for good design of stairs and ramps etc. even where disabled individuals are not the design target.
- ANSI A117.4 Accessible and Usable buildings and Facilities (earlier version was incorporated into the ADA)
- ASTM F 1637, Standard Practice for Safe Walking Surfaces, (Similar to the above standards)
- America's Favorite Homes, mail-order catalogues as a guide to popular early 20th-century houses, Robert Schweitzer, Michael W.R. Davis, 1990, Wayne State University Press ISBN 0814320066 (may be available from Wayne State University Press)
- American Plywood Association, APA, "Portland Manufacturing Company, No. 1, a series of monographs on the history of plywood manufacturing",Plywood Pioneers Association, 31 March, 1967, www.apawood.org
- ASHRAE resource on dew point and wall condensation - see the ASHRAE Fundamentals Handbook, available in many libraries. The following three ASHRAE Handbooks are also available at the InspectAPedia bookstore in the third page of our Insulate-Ventilate section:
- 2005 ASHRAE Handbook : Fundamentals : Inch-Pound Edition (2005 ASHRAE HANDBOOK : Fundamentals : I-P Edition) (Hardcover), Thomas H. Kuehn (Contributor), R. J. Couvillion (Contributor), John W. Coleman (Contributor), Narasipur Suryanarayana (Contributor), Zahid Ayub (Contributor), Robert Parsons (Author), ISBN-10: 1931862702 or ISBN-13: 978-1931862707
- 2004 ASHRAE Handbook : Heating, Ventilating, and Air-Conditioning: Systems and Equipment : Inch-Pound Edition (2004 ASHRAE Handbook : HVAC Systems and Equipment : I-P Edition) (Hardcover)
by American Society of Heating, ISBN-10: 1931862478 or ISBN-13: 978-1931862479
"2004 ASHRAE Handbook - HVAC Systems and Equipment The 2004 ASHRAE HandbookHVAC Systems and Equipment discusses various common systems and the equipment (components or assemblies) that comprise them, and describes features and differences. This information helps system designers and operators in selecting and using equipment. Major sections include Air-Conditioning and Heating Systems (chapters on system analysis and selection, air distribution, in-room terminal systems, centralized and decentralized systems, heat pumps, panel heating and cooling, cogeneration and engine-driven systems, heat recovery, steam and hydronic systems, district systems, small forced-air systems, infrared radiant heating, and water heating); Air-Handling Equipment (chapters on duct construction, air distribution, fans, coils, evaporative air-coolers, humidifiers, mechanical and desiccant dehumidification, air cleaners, industrial gas cleaning and air pollution control); Heating Equipment (chapters on automatic fuel-burning equipment, boilers, furnaces, in-space heaters, chimneys and flue vent systems, unit heaters, makeup air units, radiators, and solar equipment); General Components (chapters on compressors, condensers, cooling towers, liquid coolers, liquid-chilling systems, centrifugal pumps, motors and drives, pipes and fittings, valves, heat exchangers, and energy recovery equipment); and Unitary Equipment (chapters on air conditioners and heat pumps, room air conditioners and packaged terminal equipment, and a new chapter on mechanical dehumidifiers and heat pipes)."
- 1996 Ashrae Handbook Heating, Ventilating, and Air-Conditioning Systems and Equipment: Inch-Pound Edition (Hardcover), ISBN-10: 1883413346 or ISBN-13: 978-1883413347 ,
"The 1996 HVAC Systems and Equipment Handbook is the result of ASHRAE's continuing effort to update, expand and reorganize the Handbook Series. Over a third of the book has been revised and augmented with new chapters on hydronic heating and cooling systems design; fans; unit ventilator; unit heaters; and makeup air units. Extensive changes have been added to chapters on panel heating and cooling; cogeneration systems and engine and turbine drives; applied heat pump and heat recovery systems; humidifiers; desiccant dehumidification and pressure drying equipment, air-heating coils; chimney, gas vent, fireplace systems; cooling towers; centrifugal pumps; and air-to-air energy recovery. Separate I-P and SI editions."
- Principles of Heating, Ventilating, And Air Conditioning: A textbook with Design Data Based on 2005 AShrae Handbook - Fundamentals (Hardcover), Harry J., Jr. Sauer (Author), Ronald H. Howell, ISBN-10: 1931862923 or ISBN-13: 978-1931862929
- Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Amazon.com and also Wiley.com. See our book review of this publication.
- Building Research Council, BRC, nee Small Homes Council, SHC, School of Architecture, University of Illinois at Urbana-Champaign, brc.arch.uiuc.edu. "The Small Homes Council (our original name) was organized in 1944 during the war at the request of the President of the University of Illinois to consider the role of the university in meeting the demand for housing in the United States. Soldiers would be coming home after the war and would be needing good low-cost housing. ... In 1993, the Council became part of the School of Architecture, and since then has been known as the School of Architecture-Building Research Council. ... The Council's researchers answered many critical questions that would affect the quality of the nation's housing stock.
- How could homes be designed and built more efficiently?
- What kinds of construction and production techniques worked well and which did not?
- How did people use different kinds of spaces in their homes?
- What roles did community planning, zoning, and interior design play in how neighborhoods worked
- The Circular Staircase, Mary Roberts Rinehart
- Energy Savers: Whole House Systems Approach to Energy Efficient Home Design [copy on file as /interiors/Whole_House_Energy_Efficiency_DOE.pdf ] - U.S. Department of Energy
- "Energy Savers: Whole-House Supply Ventilation Systems [copy on file as /interiors/Energy_Savers_Whole-House_Supply_Vent.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11880?print
- "Energy Savers: Whole-House Exhaust Ventilation Systems [copy on file as /interiors/Energy_Savers_Whole-House_Exhaust.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11870
- "Energy Savers: Ventilation [copy on file as /interiors/Energy_Savers_Ventilation.pdf ] - ", U.S. Department of Energy
- "Energy Savers: Natural Ventilation [copy on file as /interiors/Energy_Savers_Natural_Ventilation.pdf ] - ", U.S. Department of Energy
- "Energy Savers: Energy Recovery Ventilation Systems [copy on file as /interiors/Energy_Savers_Energy_Recovery_Venting.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11900
- "Energy Savers: Detecting Air Leaks [copy on file as /interiors/Energy_Savers_Detect_Air_Leaks.pdf ] - ", U.S. Department of Energy
- "Energy Savers: Air Sealing [copy on file as /interiors/Energy_Savers_Air_Sealing_1.pdf ] - ", U.S. Department of Energy
- Gypsum Construction Guide, National Gypsum Corporation
- Gypsum
Construction Handbook [purchase at Amazon.com] H17, Technical
Folder SA920 and PM2, PM3 and PM4, United States Gypsum Company, 125 South Franklin ST., PO Box 806278, Chicago, IL 60680-4124,
- Humidity: What indoor humidity should we maintain in order to avoid a mold problem?
- Ice Dam Leaks in building attics and roof cavities, how to inspect for evidence of leaks, identify causes, and
- What Style Is It?: A Guide to American Architecture, Rev., John C. Poppeliers, S. Allen Chambers, Wiley; Rev Sub edition (October 6, 2003), ISBN-10: 0471250368, ISBN-13: 978-0471250364
- ...
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