Cement board and Ditra are two popular underlayment options for tile installations. Both provide a durable, water-resistant surface for installing tile, but they have some key differences. Determining which is better depends on the specific project requirements.
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What is cement board?
Cement board, also known as backerboard, is a building material made of portland cement reinforced with fiberglass mesh. It is commonly used as a tile backing board for walls and floors. Some key features of cement board include:
- Waterproof and moisture-resistant
- Prevents cracks from transferring from substrate to tile
- Adds structural strength
- Made from sustainable materials
- Resists mold and mildew
Popular brands of cement board include Hardiebacker, Durock, PermaBase, and WonderBoard.
What is Ditra?
Ditra is a polyethylene underlayment that provides uncoupling and waterproofing for tile installations. It is a thin, flexible mat with square cutback cavities on the bottom that allow for thin-set mortar coverage. Key features of Ditra include:
- Uncouples tile from subfloor to prevent cracking
- Waterproofs installation
- Allows for thin-set application on floors
- Lightweight and easy to install
- Made from recycled materials
Ditra is a product manufactured by Schluter Systems.
Main Differences
Here is an overview of the main differences between cement board and Ditra:
| Feature | Cement Board | Ditra |
|---|---|---|
| Material | Fiberglass reinforced portland cement | Polyethylene |
| Thickness | 1/4″ – 1/2″ | 1/8″ |
| Waterproofing | Water-resistant only | Fully waterproofs |
| Crack isolation | Does not uncouple | Provides uncoupling |
| Installation | Cuts like wood, fastened with screws | Rolls out and adheres with thin-set |
| Floors | Not suitable for floors | Can be used for floors |
| Weight | Heavier | Lightweight |
| Cost | $$ | $$$ |
As shown, cement board is thicker, more rigid, and made of different materials than Ditra. Ditra offers more flexibility, full waterproofing, and uncoupling properties that cement board lacks. However, Ditra also comes at a higher cost than most cement boards.
When to use cement board
Here are some of the main situations where cement board would be the preferred underlayment option:
- Tile walls in dry areas
- Floor installations over plywood or OSB subfloors
- Outdoor tile installations
- Tile backsplashes
- Shower walls only (requires separate waterproofing membrane)
- Radiant heat floor systems
- Floor installations with electric wire heating
- Budget projects where cost is main concern
Cement board is a good choice when waterproofing is not needed or will be provided by a membrane. It provides a durable, rigid substrate for tile. It is also more affordable than Ditra.
Cement Board Benefits
- Lower cost material
- Rigid support for tile
- Prevents subfloor cracks from transferring
- Compatible with radiant heating systems
- Wide availability
When to use Ditra
Here are situations where Ditra would be the preferable underlayment choice:
- Tile floors in rooms with moisture exposure like bathrooms and laundries
- Tile floors over concrete slabs
- Heated tile floors (hydronic systems)
- Crack isolation needed under tile
- Wood subflooring with higher deflection
- Thin-set tile installation over vinyl
- Shower floors and walls in wet areas
- Small surfaces like countertops
- Tile over existing tile
Ditra is ideal for any installation where waterproofing and crack isolation is critical. Its thin profile and flexibility also make it suitable for many surfaces cement boards cannot accommodate.
Ditra Benefits
- Provides full waterproofing
- Uncouples to prevent tile cracks
- Allows for thinner profile
- Lightweight and easy to install
- Can be applied over many surfaces
Installation Comparison
Installing cement board vs Ditra also involves some different considerations:
Cement Board Installation
- Cut to size using carbide scoring tool or utility knife
- Fasten to substrate with cement board screws
- Tape seams with fiberglass mesh tape
- Install uncoupling membrane for waterproofing (if needed)
- Apply mortar and install tile
Cement board requires more cutting and fastening for installation. Seams, corners, and fastener locations need special attention.
Ditra Installation
- Roll out Ditra mat over floor or apply membrane to walls
- Cut with utility knife as needed
- Seal seams with Ditra tape
- Apply thin-set mortar directly over Ditra
- Set and grout tiles
Ditra installs faster with just thin-set application and does not require fasteners or special seam treatments.
Cost Comparison
On average, Ditra costs $1.00-2.00 per square foot more than cement backerboard. A typical 50 sq ft bathroom would cost:
- Cement board – $75
- Ditra – $100-$125
However, Ditra can provide longer-term value through better crack resistance and waterproofing. The cost difference is minor for a full bathroom installation.
Cement Board vs Ditra for Showers
For shower installations, Ditra often provides more advantages over cement board:
| Cement Board | Ditra | |
|---|---|---|
| Waterproofing | Requires separate membrane | Fully waterproofs |
| Installation | Harder to cut and fasten | Easier install around drains |
| Crack resistance | Rigid, transfers substrate cracks | Uncoupled system resists cracks |
| Thinset thickness | Requires thicker mortar layer | Allows thinner bond coat |
The crack isolation, waterproofing, and ease of install with prefabricated slopes give Ditra an advantage for shower floors. Ditra also excels for shower walls compared to cement board.
Cement Board vs Ditra for Bathrooms
For bathroom floors, Ditra is generally the preferred method as well. Reasons to choose Ditra include:
- Fully waterproofs floor
- Thinner profile without losing strength
- Allows for large format tiles and thinner grout lines
- Uncouples floor from subfloor
- Accommodates radiant heating systems
Cement board can work for bathrooms over wood subfloors. But Ditra provides more advantages for proper waterproofing and crack resistance.
Cement Board vs Ditra for Walls
On walls, cement board remains a viable option against Ditra. Cement board has several benefits for walls:
- Rigid substrate won’t flex
- Provides higher pullout strength for tiles
- Less expensive
- Simpler fastener installation
Ditra is still preferable for wet walls like showers. But for dry wall areas, the choice depends on the project needs and budget.
Conclusion
For most tile installations, Ditra provides advantages in waterproofing, crack isolation, and ease of installation. The cost is moderately higher than cement board but worth the investment for bathrooms, showers, and floors with higher deflection.
Cement board remains a viable option, especially for walls and dry areas. It provides a rigid, flat substrate for tile at a lower cost. Cement board is also compatible with radiant heating systems.
In summary:
- Ditra is preferable for: Shower floors and walls, bathroom floors, substrates with movement or deflection
- Cement board is preferable for: Tile walls in dry areas, tile floors over plywood/OSB, radiant heat systems, outdoor installations
The best option depends on the specific project needs. But when in doubt for bathrooms and wet areas, Ditra often provides the better performance and protection.