Below Ground Waterproofing and Tanking in Auckland: Systems, Standards & Solutions

“In Auckland, moisture doesn’t take a day off. Neither should your building’s waterproofing.”

— Auckland Waterproofing Experts

This guide covers tanking systems in detail. For the complete basement renovation process including costs and consent, see our comprehensive basement renovations guide

Peel and Stick Tanking Membrane

Below ground tanking involves installing durable waterproof barriers to the outside (and sometimes inside) of any part of a building that sits below ground level (like basements, cellars, or retaining walls). The goal is simple: stop water from finding its way into occupied or structural spaces, preventing leaks, mould, and long-term damage.

Why It Matters in Auckland:

Whether you’re building new or renovating, tanking is an investment in your building’s health, resale value, and liveability.

Like roofing, Auckland’s underground environments face multiple, sometimes competing, threats:

Risk Factors:

Not all tanking systems are made equal. The right product depends on site conditions, budget, expected service life, and council requirements.

Key NZ Brands:

• Viking Peel & Stick (self-adhesive)
• Nuralite Nuraply 3PT (torch-on)
• ARDEX Shelterseal WPM3000x
• Volclay Swelltite
• SIKA Blackseal

Product Comparison Table

System selection must consider: expected water pressure, substrate, temperature at install, accessibility for repairs, and compatibility with other drainage elements.

NZ Context

Council & Compliance Checklist:

• Ensure substrate readiness (clean, dry, correct surface)
• Use only approved membranes with warranty
• Maintain full product documentation & photographic installation records
• Flood test before backfill/covering
• Use only LBP (Licensed Building Practitioner)

1. Site Assessment
   • Survey water table, drainage, soil type, and ground movement risks.
   • Identify and remedy cracks or structural defects.
2. Surface Preparation
   • Excavate all relevant below-ground walls and slab edges.
   • Clean, repair, and prime surfaces.
   • Install drainage (subsoil/French drain) if not present.
3. Detailing/Joint Preparation
   • Flash all joints, penetrations, construction/service (pipe) inlets.
   • Apply corner reinforcement and bond breakers as per manufacturer.
4. Membrane Installation
   • Self-Adhesive: Apply primer; stick sheets to wall/floor, roll with pressure.
   • Torch-on: Heat-apply membrane—ensure full weld at overlaps.
   • Bentonite: Place sheet with overlaps; backfill carefully to activate.
   • Liquid Applied: Apply by brush or spray, multiple coats, cure as specified.
5. Inspection & Testing
   • Inspect for coverage gaps, wrinkles, or weak seams.
   • Document with photographs.
6. Protection & Backfilling
   • Apply protection boards/mesh to prevent membrane puncture during backfilling.
   • Reinforce protection with Polystyrene.
   • Backfill with Scoria.
7. Final Certification
   • Auckland Council Inspection.
   • LBP signoff, producer statement, manufacturer’s warranty secured.

Pro Tip: Once tanking is covered, fixing failures is extremely costly—get it right the first time.

What to watch out for: bubbling plaster, water stains, or musty odours are early red flags.

Expertise is everything—this isn’t a DIY job. Look for:

• Tanking is mission-critical below ground in Auckland’s wet environment.
• Choose proven, council-approved systems and experienced installers—don’t cut corners.
• Regular inspection and proactive maintenance guarantee dry, healthy, and saleable underground spaces.