Is cement board or foam board better as a tile backer in a wet area?

Both cement board and foam board (such as Schluter Kerdi-Board or Wedi) are code-compliant tile backer options for wet areas in Ontario, but they represent fundamentally different approaches — and your choice depends on the specific bathroom project, budget, and installation expertise. Each system has clear advantages that make it better suited to certain situations in GTA bathroom renovations.

Cement board — products like Durock, Wonderboard, and HardieBacker — is the traditional standard for wet-area tile backing in GTA bathrooms. It's a rigid panel made of Portland cement and fibreglass mesh that does not deteriorate when exposed to water. However, cement board itself is not waterproof — water passes through it freely. It must be used in combination with a separate waterproof membrane (RedGard liquid membrane, Schluter Kerdi sheet membrane, or similar) applied over the cement board surface before tile installation. The cement board provides the rigid, stable substrate; the membrane provides the waterproofing.

Foam board systems — most notably Schluter Kerdi-Board and Wedi board — are rigid extruded polystyrene panels with a factory-applied waterproof fleece facing. These panels serve as both the tile backer and the waterproof membrane in a single product. The waterproofing is built into the board itself, eliminating the need for a separate membrane application step. The seams and fastener penetrations are sealed with matching waterproof accessories (Kerdi-Band for Schluter, or Wedi joint sealant).

Comparing the Two Systems

Cost is the most significant difference for most GTA homeowners. Cement board runs $12–$18 per 3x5 sheet plus the cost of a waterproof membrane ($80–$150 per pail of liquid membrane, or $2–$4 per square foot for sheet membrane). Foam backer board costs $40–$90 per panel depending on thickness and brand, but you skip the separate membrane step. For a standard shower surround, the total material cost is often comparable — cement board plus membrane versus foam board alone — but the labour savings with foam board can be significant since you're eliminating the membrane application step entirely.

Weight matters in certain GTA renovation scenarios. Cement board is heavy — a half-inch 3x5 sheet weighs about 36–45 pounds. Foam backer board is dramatically lighter at roughly 3–5 pounds for an equivalent panel. In condo bathroom renovations where materials must be transported via elevator and through hallways, the weight difference is a practical consideration. It also matters for wall-mounted applications where substrate framing may be lighter-gauge steel studs (common in condos) rather than wood framing.

Ease of cutting and installation favours foam board. Cement board requires scoring and snapping or cutting with a carbide-tipped blade, generating significant dust. Foam board cuts easily with a utility knife. For complex layouts with niches, angles, and curved walls, foam board is considerably more workable.

Durability and track record favours cement board. It has been the standard wet-area backer in North American construction for decades. When combined with a properly installed waterproof membrane, cement board assemblies have a proven long-term performance record. Foam board systems are newer — Schluter and Wedi have excellent reputations, but the systems rely on correct seam sealing for waterproof integrity. A missed seam or improperly sealed penetration in a foam board system compromises the entire waterproof envelope.

The Recommendation for GTA Bathrooms

For most GTA bathroom renovations, cement board with a liquid-applied or sheet membrane remains the most common professional choice — it's what the majority of Toronto-area tile installers are trained on and comfortable with. If you're hiring a contractor, ask what system they prefer and have the most experience installing. A properly executed cement board and membrane system is extremely reliable.

Foam board systems are excellent for condo renovations (lighter weight, less dust, faster installation in tight spaces), DIY-friendly tub surrounds (simpler waterproofing integration), and projects where reducing installation steps saves meaningful time and cost.

Whichever system you choose, the Ontario Building Code requires a continuous waterproof barrier in all shower and tub surround wet areas. This is not optional, and it is the single most critical layer in preventing long-term water damage. Both systems satisfy this requirement when installed according to manufacturer specifications.