Below Ground Tanking in Auckland: Systems, Standards & Solutions

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

— Auckland Waterproofing Experts

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.