What should I expect to pay for upgrading a bathroom subfloor from plywood to cement board in a Vancouver home?

Replacing a bathroom subfloor with cement board in Metro Vancouver typically costs $800–$2,500 for a standard bathroom, depending on the size of the space, the condition of the existing structure, and whether any rot or water damage is discovered once the old flooring is removed.

This is one of those projects where the quoted price and the final price can diverge — not because contractors are being dishonest, but because bathroom subfloors in older Vancouver homes frequently hide moisture damage, rot, or deteriorated joists that only become visible after demolition. Budget a contingency of 15–20% above your quote for this reason.

What Drives the Cost

Labour is the dominant cost factor. Removing existing flooring, inspecting the subfloor, cutting and fitting cement board panels, fastening them correctly, and taping seams typically takes a skilled installer 4–8 hours for a standard 50–80 square foot bathroom. At Metro Vancouver trade rates of $75–$120 per hour, that puts labour alone at $300–$960. Material costs for cement board (HardieBacker, Durock, or equivalent) run $1.50–$3.00 per square foot, so materials for a typical bathroom add another $75–$240.

Where costs escalate is when the subfloor beneath reveals problems. If the existing plywood is water-damaged — common in Vancouver bathrooms that have had leaking toilets, failed caulking, or inadequate waterproofing — the plywood itself needs replacing before cement board goes down. Plywood subfloor replacement adds $500–$1,500 depending on extent. If joists are damaged, you're looking at structural repairs that can push the total well past $3,000.

Metro Vancouver Context

Vancouver's persistent humidity and rainfall make subfloor moisture damage more common here than in drier parts of Canada. Homes built before 1980 in East Vancouver, Burnaby, New Westminster, and the North Shore frequently have original plywood subfloors that have absorbed decades of moisture from improperly sealed tub surrounds, condensation, and slow toilet base leaks. When a contractor pulls up the old vinyl or tile, finding soft, discoloured, or delaminated plywood is not unusual — it's almost expected in bathrooms that haven't been renovated in 20+ years.

Cement board is mandatory in wet areas — not optional. BC Building Code Section 9.29 and industry best practice both require a non-organic, dimensionally stable substrate behind any tile in a shower, tub surround, or bathroom floor. Standard plywood alone is not an acceptable tile substrate in wet areas because it swells and contracts with moisture changes, causing grout to crack and tile to loosen over time. In Vancouver's humidity, this failure happens faster than in drier climates.

Practical Tips

Cement board panels should be fastened with corrosion-resistant screws (not nails) at 6–8 inch spacing along edges and 8 inch spacing in the field — this is the manufacturer specification and what your contractor should be following. All seams and corners must be taped with alkali-resistant mesh tape and thinset before tile goes down. The cement board surface should be flat to within 3mm over 3 metres — any high spots or gaps create a weak point that telegraphs through tile over time.

If you're replacing the subfloor as part of a larger bathroom renovation (new tile floor, shower rebuild, vanity replacement), it makes sense to bundle this work rather than treat it as a standalone project. The mobilization cost is already absorbed, and the floor will be exposed anyway.

This is firmly in professional territory. Proper subfloor preparation is the foundation — literally — of a tile installation that lasts 15–25 years versus one that starts cracking and loosening within 3–5 years. A licensed tile setter or general contractor with bathroom renovation experience should handle this work.

Need help finding a bathroom renovation contractor in Metro Vancouver? Vancouver Bathrooms can match you with local professionals at no cost — browse the Vancouver Construction Network directory at vancouverconstructionnetwork.com/directory?trade=bathroom-renovations.