Professional Bathroom Renovations in Toronto

Why Schluter Kerdi Waterproofing Is Non-Negotiable

Before systems like Schluter Kerdi existed, showers were waterproofed using PVC or CPE liners — thin plastic sheets laid beneath the mortar bed on the shower floor. This method was standard through the 1970s, 80s, and into the 90s. The problem is that these liners sit below the tile and mortar, creating a gap where moisture gets trapped. Over time, that trapped water breaks down the mortar bed from beneath, weakens the bond between the tile and substrate, and eventually finds its way through seams, corners, and drain connections.

The result is a slow, hidden leak that rots the subfloor, damages joists, and often goes undetected until the shower floor feels spongy underfoot or water appears on the ceiling below. At that point, the entire shower base — tile, mortar, liner, and often the subfloor — needs to be torn out and rebuilt. We've seen this exact failure in dozens of Toronto homes, especially in century homes and older builds across Roncesvalles, The Annex, and The Beaches.

Schluter Kerdi eliminates this problem entirely. Instead of a buried liner, Kerdi is a bonded polyethylene membrane applied directly to the wall and floor substrate — above the waterproofing layer, not below it. Tile is set directly onto the membrane with thin-set mortar, creating a continuous, vapor-tight barrier with no gaps for moisture to accumulate. No trapped water. No mortar breakdown. No hidden rot.