Water damage is one of the most common and costly problems facing New Zealand buildings - and one of the most preventable. New Zealand's high rainfall, humidity, and temperature swings create conditions where poorly waterproofed surfaces deteriorate fast. What starts as a minor moisture issue behind a bathroom tile can become structural damage, mould, and remediation bills that dwarf the original build cost.
Getting waterproofing right the first time is straightforward if you understand what the products are actually doing, and which system suits the job.
Why NZ conditions demand quality membranes
New Zealand has some of the highest weathertightness failure rates in the developed world - a legacy of the leaky homes era that cost the country billions. The building code has tightened significantly since then, but the fundamental problem remains: water finds any gap, and once it's inside a structure it does damage slowly and invisibly.
Internal wet areas - bathrooms, shower recesses, laundries, domestic kitchens - are the highest-risk zones. These spaces see daily water exposure, steam, cleaning chemicals, and thermal cycling. A waterproofing membrane applied beneath the tile layer is your last line of defence. If it fails, the water is already inside the substrate.
What to look for in a waterproofing membrane
Not all liquid membranes are equal. For internal wet area applications, you want a product that is:
- Single-component - no mixing errors on site
- Solvent-free - safe to use in enclosed spaces
- Highly elastic - able to bridge minor substrate movement without cracking
- Compatible with your tile adhesive system - membranes and adhesives need to work together or you risk delamination
EzyMix's EM 240 Internal Waterproofing Membrane ticks all four. It's a highly elastic, single-component, solvent-free liquid membrane designed specifically for under-tile waterproofing on walls and floors in bathrooms, showers, sanitary facilities, and domestic kitchens. Critically, it holds BRANZ Appraisal No. 1299 - independent third-party verification that the product performs as specified under New Zealand conditions. That's not a marketing claim; it's a documented technical assessment.
Application: what actually matters on the job
Coverage rate for EM 240 is 1.6kg/m² per millimetre of thickness. Two coats are required, with approximately two hours drying time between coats - and the surface is ready for tile covering within 24 hours. Application temperature range is 5°C to 30°C ambient, which covers most NZ working conditions year-round.
Surface preparation matters as much as product selection. Even the best membrane won't perform on a substrate that's dusty, damp, or structurally unsound. Surfaces should be clean, dry, and free from contaminants before you start. Where substrates are porous or variable, a compatible primer - such as EzyMix EM 230 Tile Primer FG or EM 231 SpG Tile Primer - should be applied first to ensure even absorption and proper adhesion of the membrane.
Don't skip the tape. Internal and external corners, floor/wall junctions, and penetrations (drains, pipes) are where membranes are most vulnerable. Reinforcing tape pressed into the wet first coat at these points is standard practice and significantly reduces the risk of failure at the joins.
Building compliance
NZ building regulations place strict requirements on waterproofing in wet areas. Membrane thickness, application method, curing times, and system compatibility are all part of compliance - not just product selection. Using a BRANZ-appraised product like EM 240 alongside manufacturer documentation simplifies this process, because the technical data has already been independently reviewed.
Always follow the product's Technical Data Sheet and ensure your complete system - primer, membrane, tape, and tile adhesive - is compatible. EzyMix can provide technical support and product documentation for the full waterproofing system.
For more information
The full EzyMix waterproofing range - including the EM 240 IWM, tile primers, sealing tapes, and corner accessories - is available at ezymix.co.nz. Request a quote or get in touch with the team for product specifications and system guidance.
