How much does it cost to retile a shower that has water damage behind the existing tile?

Retiling a shower with water damage behind the existing tile is one of the more expensive bathroom repair projects because it is never just a retile — it is a full tear-out, structural assessment, repair, and rebuild. In Ottawa, expect to pay $5,000 to $15,000 or more for a complete water-damaged shower remediation and retile, depending on the extent of the damage, shower size, and your tile selections.

Here is where that cost comes from, broken down into the major phases. Demolition and tear-out of existing tile, backer board, and damaged materials runs $500 to $1,500. This is messy, labour-intensive work — the old tile comes off, the backer board behind it is removed, and the condition of the studs and framing is exposed and assessed. Mould remediation, if present, adds $500 to $3,000 depending on severity. Surface mould on studs can often be treated with antimicrobial solutions by the tile contractor, but extensive mould that has penetrated the wood framing or spread to adjacent wall cavities may require a professional mould remediation company with containment and air filtration equipment.

Structural repair — replacing rotted studs, sistering damaged framing, replacing the subfloor or shower pan base — adds $500 to $2,500. Water damage behind shower tile in Ottawa homes is rarely confined to a small area by the time it is discovered. The typical scenario is that water has been slowly migrating through failed waterproofing or deteriorated grout for months or years, softening the wood framing and creating ideal conditions for mould growth. By the time the homeowner notices soft spots, discoloured grout, or a musty smell, the damage has usually spread well beyond the visible problem area.

New substrate and waterproofing — installing cement board and a proper waterproofing membrane (Schluter Kerdi, RedGard, or equivalent) — runs $800 to $2,000. This is the single most important phase, because the original failure was almost certainly caused by inadequate or absent waterproofing. Many Ottawa showers built before 2010 used only a vapour barrier (plastic sheeting) behind cement board, which is not a true waterproofing system and allows moisture to reach the framing over time.

Tile installation on the new waterproofed substrate runs $1,500 to $5,000 depending on shower size and tile selection. A standard 3-by-5-foot shower surround with porcelain wall tile and mosaic floor tile falls in the $2,000 to $3,500 range including materials and labour.

The timeline for this type of project in Ottawa is typically 5 to 10 working days, depending on the extent of structural repair needed and drying times for waterproofing membranes and mould treatments. Winter projects may take slightly longer because adhesive curing times are affected by the cold, dry indoor air typical of Ottawa's heating season.

This is absolutely a project for a professional tile contractor with waterproofing experience. You can find experienced tile installers through the Ottawa Construction Network directory at justynrookcontracting.com/directory — look for contractors who specifically list shower waterproofing and remediation in their services.

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Looking for experienced contractors? The Ottawa Construction Network connects Ottawa homeowners with qualified professionals:

• Justyn Rook Contracting
• RenoMotion Inc.
• JMY Renovations
• Dreamwood Construction & Renovations
• Dump n Dash Hauling