Tile backer board, also known as cement board or wonder board, is an essential underlayment material for any tile installation. Installing tile directly onto drywall or wood can lead to cracks, damage, and loose tiles over time as those materials flex and move. Tile backer board provides a rigid, stable substrate that won’t be affected by moisture.
When properly installed, tile backer board creates a durable, stable surface for tile installations in wet areas like bathrooms, kitchens, and laundry rooms. But all backer board is not the same. There are a few key factors to consider when choosing the right backer board for your tile project.
Types of Tile Backer Board
Cement Board
Cement board, commonly referred to by the brand name Hardibacker, is the most popular and commonly used backer board for tile installations. It is made from Portland cement sandwiched between two layers of fiberglass mesh.
Pros:
- Extremely durable and rigid
- Dimensionally stable even in moist environments
- Won’t deteriorate over time
- Fire and mold resistant
Cons:
- Heavy and more difficult to cut and install
- Needs sealing at all penetrations and seams
Cement backer board costs $8-10 per square foot on average. It can be used for wall or floor installations. Look for products made specifically to meet ANSI standards for cement board when used as a tile backer.
Fiber-Cement Board
Fiber-cement boards such as Durock and Fiberock are also cement-based backers reinforced with fiber. However, instead of fiberglass mesh, they use wood pulp or synthetic fibers.
Pros:
- Lightweight yet strong and rigid
- Dimensionally stable
- Easy to score and snap cut
- Mold and moisture resistant
Cons:
- More expensive than cement board
- Not quite as rugged and abuse-resistant
Fiber-cement boards cost $9-12 per square foot on average. They can be used on walls or floors in dry and wet areas.
Wood-Plastic Composite Board
Composite tile backer boards like Schluter Ditra and Wedi provide a lightweight alternative to cement boards. They feature a waterproof plastic core laminated between fiberglass or cement board facers.
Pros:
- Extremely lightweight and easy to install
- Naturally waterproof and vapor retardant
- Doesn’t require seam sealing or membrane
Cons:
- More expensive
- Not as durable or rigid as cement options
- For wall applications only, not floors
At $15-20 per square foot, composite boards are the priciest backer board option. But the ease of installation and inherent waterproofing may justify the cost for some.
Where to Use Tile Backer Board
Tile backer board is required as a substrate anywhere you are installing tile in a wet area:
- Showers
- Bathroom walls and floors
- Kitchen backsplashes
- Laundry and utility rooms
- Entryways and mudrooms
- Patio and balcony tile
- Pool tile
- Anywhere moisture is present
Backer board is also recommended in dry areas like:
- Living rooms
- Bedrooms
- Dining rooms
- Media rooms
Anywhere you might install tile on walls or floors inside your home, backer board is the best practice to create a stable, long-lasting tile foundation.
Wood and drywall are not suitable substrates for tile. Backer board prevents cracks, loose tiles, and other failures over time.
How to Install Tile Backer Board
Installing tile backer board takes a little more time and effort than drywall but it’s a straightforward process. Be sure to wear proper safety gear like gloves, eye protection, and a dust mask when cutting and installing backer board.
Prep the Surface
The substrate must be clean, dry, and structurally sound. Remove any existing flooring, screw down subfloors to avoid squeaking, and address any water damage or mold issues prior to installation.
For wall installations, make sure framing is properly spaced at 16″ on center and plumb.
Cutting Backer Board
The cementitious boards can be scored and snapped using a utility knife and straightedge. Cut through the mesh just into the cement layer on both sides, then snap the board backwards to break the cut.
Composite boards require a circular saw with a fine-toothed fiber-cement blade. Cut boards to size allowing a 1/4″ gap between board edges.
Cutouts for plumbing, drains, and other penetrations can be made using the score and snap method or an oscillating multi-tool.
Fastening
Use galvanized or ceramic coated screws to fasten the backer board to wall studs or floor joists. Max spacing is 8″ on center. Countersink all screws approx. 1/8″ with a drill.
All board seams and corners must be supported by framing or back-buttered with mortar when tiling. Leave a 1/8″ gap between board edges.
Sealing and Waterproofing
Any penetrations in cement board must be coated with a waterproof sealant designed for cement board. Mesh tape embedded in sealant should be used at all seams and corners.
Composite boards like Ditra are waterproof so no additional sealing is needed. Simply install according to manufacturer instructions.
Some codes require a waterproofing membrane over the entire substrate before tiling. Check local regulations.
Once the backer board is properly fastened, sealed, and waterproofed, it’s ready for tile installation. Refer to the manufacturer instructions for detailed steps.
FAQs
Is backer board necessary for tile installation?
Yes, backer board is essential anywhere you are installing tile in a wet area. It prevents loose tiles, cracks, and damage over time caused by substrate movement. Tile requires a rigid, dimensionally stable foundation.
Can you use drywall as a tile backer?
No, drywall should never be used as a backer board for tile. It will deteriorate quickly under the weight and moisture exposure.
Can I install tile backer board over drywall or plaster?
Yes, in dry areas only. The backer board must be fastened securely to wall studs, not just glued onto the drywall.
Can I tile onto plywood floors?
Plywood is not a suitable substrate for floor tile. An underlayment like cement backer board must be installed over the plywood before tiling.
Is cement board waterproof?
Cement backer boards are water resistant but not completely waterproof. Seams, corners, and penetrations must be sealed with a waterproof coating.
Should backer board go under or over wall tile in a shower?
Cement backer board should go behind both the wall tile and shower pan tile up to the ceiling. This prevents moisture from seeping through grout lines and tiles.
How thick should backer board be for floor tile?
Use 1/2″ thick cement backer board for floor tile installations. It provides the durability and strength needed for high-traffic floor applications.
Can I install radiant heat under backer board?
Yes, follow manufacturer instructions for proper installation of electric or hydronic radiant heating systems under cement backer boards.
How do you cut holes in backer board?
Use a carbide grit hole saw or oscillating tool to cut clean circular holes. Score and snap method can also be used to cut square or rectangular openings.
Conclusion
Choosing the right tile backer board and properly preparing the substrate is a crucial first step for a successful tile installation. Cement board, fiber-cement board, and composite boards each offer different benefits depending on your specific needs.
Be sure to follow all manufacturer instructions carefully throughout the installation process. With sturdy, well-installed backer board behind your tiles, you can enjoy a beautiful, lasting finish that stands the test of time and moisture. Investing in the proper backer board provides peace of mind that your tile won’t crack, loosen, or deteriorate over the years.
