Hydrepoxy Basement Waterproofing in Auckland

If water is weeping through your basement walls, pooling on the slab, or leaving salt bloom and musty smells on paintwork — the fix is almost never another coat of paint. It’s a properly engineered waterproofing system.

On Auckland jobs, we use ARDEX WPM 300 (HydrEpoxy) — a two-component water-based epoxy barrier coating that bonds directly to concrete and block (including damp and green surfaces), withstands hydrostatic pressure up to 250 kPa (equivalent to a 25-metre head of water), and is fully compatible with Auckland Council’s PS3 sign-off process.

What HydrEpoxy Is

• A two-component water-based epoxy barrier coating — it forms a tough physical film on the substrate surface
• Bonds directly to damp surfaces and green concrete — no need to wait for the substrate to dry before application
• Withstands up to 250 kPa of hydrostatic pressure (equivalent to a 25-metre head of water)
• Prevents rising damp and the formation of efflorescence when used as a single or double coat barrier
• Applied in two coats by roller; full cure 7 days
• Potable drinking water compliant — AS/NZS 4020:2018 and SS375-2001
• Can be overcoated with decorative or industrial finishing coatings including epoxy floor systems, paints, and tile adhesives

When It’s the Right System (and When It’s Not)

Right for:

• Leaking block or concrete basement walls below ground
• Retaining-wall interiors where excavation is impractical
• Garage pits and lift shafts
• Concrete slab dampness where moisture vapour emission exceeds 80% RH or 15 g/m²/24hrs
• Any negative-side application where substrate moisture content is high

Not ideal for:

• Flexible substrates or timber framing — use Viking Peel & Stick or ARDEX liquid-applied membranes instead
• Trafficable surfaces — HydrEpoxy is not rated as a trafficable coating
• Decks and balconies (see our [deck waterproofing guide])

Our Waterproofing Process

1. Site visit & moisture assessment — we measure, photograph and identify the water’s entry path
2. Written quote — itemised, fixed where possible, no “allowance” line items
3. Substrate prep — the concrete or blockwork must be mechanically prepared by the main contractor or a specialist grinder to remove coatings, curing compounds, oils, laitance and salt efflorescence, and to chase and repair any cracks that are wider then 2 mm as required. We can carry out minor preparation (light wire‑brushing and small efflorescence clean‑ups) as part of our works, but where significant grinding or repair is needed this will need to be completed by your builder (we can recommend trusted contractors if required)
4. HydrEpoxy application — two coats by roller at 3.0 m²/L per coat; recoat after minimum 4 hours; applied directly to the damp prepared surface
5. Cure & test — 7-day full cure; water-spray or flood test where appropriate
6. PS3 producer statement issued on completion if needed

What It Costs (Auckland, 2026)

Honest ranges — see our [full waterproofing cost guide for 2026] — every job quoted after site visit:

• Small basement room (≤ 6 m²): from $990 + GST
• Full basement tank (40–60 m² wall + slab): from $4800 + GST
• Retaining-wall interior per lineal metre: from $140 + GST

North Shore Coverage

We service the entire North Shore — pick your local board area:

• [Devonport-Takapuna Local Board Area] — Devonport, Takapuna, Milford, Belmont, Hauraki, Forrest Hill
• [Kaipātiki Local Board Area] — Northcote, Birkenhead, Glenfield, Beach Haven, Bayview
• [East Coast Bays] — Browns Bay, Mairangi Bay, Torbay, Long Bay
• [Upper Harbour] — Albany, Greenhithe, Schnapper Rock, Paremoremo

Related Reading

• Early Signs Your Basement Is About to Leak
• Why Is Water Coming Through My Concrete Floor?
• Basement Renovations Auckland — Planning Guide