When it comes to bathroom renovations or new builds in New Zealand, waterproofing isn’t just a technical step—it’s the foundation of a long-lasting, damage-free space. Water ingress can lead to serious structural damage, rot, mold, and costly repairs, especially in timber-framed homes (which are common throughout NZ).
That’s why choosing the right undertile waterproofing membrane is one of the most important decisions you can make.
In this article, we compare several popular waterproofing systems available in New Zealand, outlining their pros, cons, and key differences — and explain why ARDEX WeldTec WPM 750 is the system we trust at Add Value Renovations.
Understanding the stakes: why waterproofing matters in NZ homes
New Zealand’s housing stock presents unique waterproofing challenges. With high rainfall in many regions, significant humidity, and predominantly timber-framed construction, water damage is a serious concern. Once water penetrates behind tiles in wet areas, it can quickly compromise structural elements, leading to extensive and expensive repairs.
At Add Value Renovations, we’ve seen the consequences of inadequate waterproofing systems firsthand during our renovation projects. That’s why we’re meticulous about the waterproofing solutions we recommend and install.
Sheet vs. liquid membranes: the fundamental choice
Before comparing specific products, it’s important to understand the two main categories of waterproofing membranes available in New Zealand:
sheet membranes
These pre-manufactured sheets are applied to surfaces and typically joined using heat-welding or adhesives.
liquid membranes
These are applied as liquids (using brushes, rollers, or sprays) and cure to form a waterproof barrier.
Each approach has inherent advantages and limitations, particularly when considering New Zealand’s building practices and conditions.
Comparison of leading waterproofing membrane products in New Zealand
| Feature | ARDEX WPM 750 WeldTec | ARDEX WPM 001 | Sika Tite Undertile | Crommelin ONE COAT Rapid | Bostik ASA Dampfix 3 |
|---|---|---|---|---|---|
| Type | Sheet membrane (fleece-lined) | Liquid membrane (one-component) | Liquid membrane (SBR latex) | Liquid membrane (heavy-duty) | Liquid membrane (two-part) |
| Application Method | Heat-welded at laps and seams | Brush, roller, or trowel | Brush or roller | Brush or roller | Brush or roller |
| Thickness | Consistent 0.5mm | Variable | Variable | Variable | Variable |
| Drying/Curing Time | Immediate (can tile after 60 mins) | 24-48 hours before tiling | 24+ hours before tiling | Faster than standard liquid | 24 hours between coats |
| BRANZ Certification | Yes (No. 1239) | Yes | Complies with AS/NZS standards | Yes | Yes |
| Suitability for Timber | Excellent | Good | Good | Good | Good |
| Flexibility | Excellent at all temperatures | Good | High (>300% extensibility) | Good | Good |
| Installation Complexity | Requires trained installers | DIY possible | DIY possible | DIY possible | Requires mixing |
| Made in NZ | Yes | No | No | No | No |
| Typical Use Cases | Residential and commercial wet areas, especially on timber structures | Internal wet areas | Internal and external wet areas | Internal wet areas | Internal wet areas, pools |
Why add value renovations chooses ARDEX Weldtec wpm 750
In most of our large renovation projects across New Zealand, we consistently specify and install ARDEX WeldTec WPM 750. Here’s why we believe it’s the superior choice for New Zealand homes:
1. Superior performance on timber structures
New Zealand homes are predominantly built with timber framing and plywood substrates. These materials naturally experience movement due to:
- Seasonal humidity changes
- Temperature fluctuations
- Structural settling over time
ARDEX WPM 750’s fleece-lined sheet membrane is specifically designed to accommodate this movement without cracking. The heat-welded seams maintain watertight integrity even when the substrate moves, providing reliable waterproofing performance in our country’s challenging conditions.
2. Consistent thickness equals consistent protection
One of the most significant issues with liquid membranes is application inconsistency. Even with skilled applicators, thickness can vary across the installation:
- ARDEX WPM 750: Guaranteed uniform 0.5mm thickness throughout
- Liquid membranes: Thickness varies based on application technique, potentially creating vulnerable points
This factory-controlled consistency eliminates on-site variables and ensures reliable waterproofing performance in every installation we complete.
3. Heat-welded seams create superior bonds
The heat-welding process used with ARDEX WPM 750 creates a molecular bond between membrane sheets. This means:
- Seams become as strong as the membrane itself
- No reliance on adhesives that can degrade over time
- Elimination of potential weak points common in liquid membrane applications
- Long-term reliability in critical wet areas
4. Dramatically faster project completion
Time is money in renovation projects. ARDEX WPM 750 offers significant time advantages:
- Can be tiled over within 60 minutes of installation
- Liquid membranes typically require 24-48 hour waiting periods before tiling
- Reduces overall project timelines
- Allows for more efficient scheduling of trades
- Minimizes disruption for homeowners during renovations
5. Made in New Zealand for New Zealand conditions
As a locally manufactured product, ARDEX WPM 750 is specifically designed for:
- New Zealand building practices
- Local climate conditions
- Compliance with NZ building codes
- Ready availability with local technical support
6. Branz certification for peace of mind
ARDEX WPM 750’s BRANZ Appraisal (No. 1239) confirms compliance with New Zealand building standards and meets the requirements of NZBC Clause E3 Internal Moisture. This provides assurance to us as installers, and to our clients as homeowners.
The liquid membrane alternative: when might they be appropriate?
While we prefer ARDEX WPM 750 for most applications, liquid membranes do have their place in certain scenarios:
Ardex wpm 001
This one-component liquid membrane offers good durability with acrylic polymers and is suitable for internal wet areas. It’s easier to apply than sheet membranes but requires multiple coats and longer drying times.
Sika tite undertile
With high extensibility (>300%) and micro fiber reinforcement, this SBR latex modified liquid membrane works well for both internal and external applications. However, it still faces the typical limitations of variable thickness and extended drying times.
Crommelin products
Crommelin’s rapid-drying formulations offer some time advantages over traditional liquid membranes, but still can’t match the immediate installation benefits of sheet membranes.
Bostik asa dampfix 3
This two-part system offers good strength and is suitable for immersed applications like pools, but requires mixing components and typically needs a 24-hour wait between coats.
Real-world performance: what we’ve observed in our projects
At Add Value Renovations, we’ve installed numerous bathroom waterproofing systems across New Zealand. Our experience has consistently shown that bathrooms waterproofed with ARDEX WPM 750 outperform those with liquid membrane applications in several key areas:
- Installation Quality: More precise, with consistent coverage
- Long-term Reliability: Fewer callbacks for water-related issues
- Project Efficiency: Faster completion times
- Client Satisfaction: Greater peace of mind about waterproofing integrity
While the initial installation requires specialized equipment and trained installers, we believe the long-term performance benefits and reduced risk of water damage make ARDEX WeldTec WPM 750 the most cost-effective choice for quality-focused projects.
The cost consideration: value vs. price
It’s important to address the cost factor. Yes, sheet membrane systems like ARDEX WPM 750 typically have a higher initial cost than some liquid membrane alternatives. However, we encourage homeowners and builders to consider:
- The cost of failure: Water damage repairs can easily run into tens of thousands of dollars
- Project timeline savings: Faster installation means lower overall labor costs
- Long-term performance: Reduced risk of expensive remediation work
- Peace of mind: The value of knowing your waterproofing is reliable
Conclusion: why we won’t compromise on waterproofing
At Add Value Renovations, we’ve built our reputation on quality workmanship and materials that stand the test of time. That’s why we choose and recommend ARDEX WeldTec WPM 750 for most of our large renovation projects.
While it may represent a slightly higher initial investment compared to some liquid membrane options, the consistent quality, superior performance on timber structures, faster project completion, and long-term reliability make it the clear choice for discerning homeowners who want their renovation done right the first time.
Water damage repairs are exponentially more expensive than proper waterproofing. By choosing ARDEX WeldTec WPM 750, we ensure our clients receive a bathroom that not only looks beautiful on completion day but continues to perform flawlessly for years to come.
Ready to Renovate? Let’s Get it Right from the Start.
At Add Value Renovations, we don’t just renovate — we build for long-term comfort, safety, and durability. Whether you’re updating a bathroom, planning a full home renovation, or just want to make sure your waterproofing is done right, we’re here to help.
Book a free consultation today and let’s talk about how we can bring quality craftsmanship and peace of mind to your next project.
👉 Contact Us | 📞 093935658 | ✉️
