When homeowners pick out tile for a new shower, they spend a lot of time on colour, size, and pattern. That is understandable. But the most important decision in a tile shower is not the tile. It is what goes behind it. A shower that is not properly waterproofed will fail, and it usually fails in a way that is expensive to fix.
What Happens When Waterproofing Fails ¶
Water gets through grout. It gets through tile. It gets through the smallest gaps in caulk. That is normal and expected. The waterproofing layer behind the tile is what stops that water from reaching the framing and subfloor. When the waterproofing fails, water sits in the wall cavity. Over months and years, that causes mould, rot, and structural damage. We have opened walls on renovation projects and found framing that was completely compromised because a shower was built without proper waterproofing fifteen years earlier.
The Schluter System ¶
We use the Schluter-KERDI system on all our tile shower builds. KERDI is a bonded waterproofing membrane that goes directly over cement board or drywall before tile is set. It is bonded with unmodified thinset and covers the entire shower surface including corners and transitions. Schluter also makes the KERDI-DRAIN, which integrates the drain into the waterproofing system so there is no gap at the most vulnerable point of the shower floor.
Why We Do Not Use Tar Paper or Felt ¶
Older shower builds used tar paper or felt behind tile as a moisture barrier. This approach is no longer considered best practice. These materials are not bonded to the substrate, which means water can travel behind them. They also degrade over time. We do not use them on new shower builds.
What This Means for Your Budget ¶
A properly waterproofed shower costs more than a shortcut build. The Schluter system adds material cost and installation time. But a shower that fails in five years costs far more to repair than the savings from skipping proper waterproofing. We include the Schluter system in every shower quote as standard, not as an upgrade.
If you are getting quotes from multiple contractors for a bathroom renovation, ask specifically what waterproofing system they use. The answer tells you a lot about how they build.