The importance of waterproofing in tiled areas: Protect your space before it's too late
“Waterproofing Is the unsung hero behind every great tiling job.”
Why waterproofing is the unsung hero behind every great tiling job
When people admire a beautiful tiled bathroom or a luxurious kitchen splashback, they usually focus on the tiles—their color, the layout, the design. Rarely does anyone think about what’s hidden underneath. But behind every flawless tiled surface lies something even more critical: proper waterproofing.
Without it, even the most expensive tiles can turn into a nightmare of leaks, mold, structural damage, and costly repairs. In fact, waterproofing is one of the most important steps when preparing wet areas for tiling—and getting it wrong can lead to problems that are much bigger (and much more expensive) than a cracked tile or dirty grout line.
Let’s dive into why waterproofing matters so much—and why you should never skip or skimp on this vital step.
What is waterproofing in tiling?
Waterproofing in tiled areas refers to the application of specialized membranes or coatings that create a watertight barrier beneath and around tiled surfaces. This barrier stops water from penetrating into the underlying structure (such as walls, floors, and subfloors) where it could otherwise cause hidden damage over time.
Important:
Tiles and grout are water-resistant, not fully waterproof. They can slow water penetration but cannot stop it entirely—especially over time or with heavy use.
Where is waterproofing required?
According to New Zealand Building Code (NZBC Clause E3 Internal Moisture) and tiling standards like AS 3740:2021 (Waterproofing of domestic wet areas), waterproofing is mandatory in:
Showers (floors and walls)
Bathrooms and toilets
Laundries
Kitchens (especially behind sinks and splashbacks)
Balconies and terraces
Areas with underfloor heating (as moisture can seep through micro-cracks)
Why is waterproofing so important in tiled Areas?
1. Prevents water damage
Without waterproofing, moisture easily seeps through grout lines, cracks, or tile edges, saturating the substrate. Over time, this leads to:
Rotten timber framing
Damaged insulation
Swollen cabinetry
Crumbling concrete
Once water gets trapped behind tiles, it’s incredibly expensive to repair—and often means complete demolition and retiling.
2. Stops mold and mildew growth
Moist environments are perfect breeding grounds for mold and mildew. Mold not only looks ugly but also causes health problems like allergies and respiratory issues. Proper waterproofing cuts off the moisture supply mold needs to thrive.
3. Protects structural integrity
Continuous water exposure can weaken structural components like concrete slabs, screeds, and framing, compromising the strength of your entire building. Waterproofing preserves the integrity of these hidden but critical elements.
4. Extends the life of your tiling investment
Tiles, adhesives, and grout last much longer when protected from water damage. A small upfront investment in waterproofing saves thousands in future retiling or renovation costs.
5. Required for warranty and compliance
Most tile manufacturers, builders, and insurance companies require waterproofing compliance for warranties to be valid. Non-compliant waterproofing can void insurance claims in case of leaks or water damage.
Common Waterproofing Mistakes to Avoid
🚫 Skipping waterproofing because "tiles are enough"
(Tiles slow moisture but don’t stop it.)
🚫 Poor surface preparation
(Dust, oil, and contaminants must be removed for waterproofing to bond properly.)
🚫 Incorrect membrane thickness
(Applying too thin a layer won’t provide a continuous barrier.)
🚫 Not waterproofing critical junctions
(Corners, pipe penetrations, drains, and floor-to-wall transitions must be fully sealed.)
What makes a good waterproofing job?
✅ Surface properly primed before waterproofing
✅ Multiple coats applied, as per manufacturer’s specifications
✅ Correct membrane thickness (usually around 1mm dry film thickness minimum)
✅ No pinholes, bubbles, or missed spots
✅ Corners reinforced with bond breakers or waterproofing tape
✅ Water testing before tiling in critical wet areas (e.g., shower bases)
The bottom line
Waterproofing is the silent protector behind every lasting tiled surface. It guards against hidden damage, mold, structural weakening, and massive repair bills—all while keeping your bathroom, laundry, or balcony looking beautiful for decades.
Whether you’re renovating a small ensuite or tiling a luxury commercial bathroom, investing in professional waterproofing is non-negotiable for quality, durability, and peace of mind.
At Cozy Tiling, we pride ourselves on proper waterproofing and expert tiling installation with Producer Statement Authors (who can issue COUNCIL’S PS3). We don’t just make your space look good—we make sure it stays safe and strong for years to come. Contact us today to discuss your project!
