Will My Home Insurance Cover a Failed Waterproofing Job?

The short answer is: it depends. Most New Zealand home insurance policies cover sudden and accidental damage, but they typically exclude damage caused by poor workmanship, lack of maintenance, or gradual deterioration — which is exactly how most waterproofing failures are classified. Understanding the difference is crucial before you make a claim or commission waterproofing work.

How NZ Home Insurance Generally Works

New Zealand home insurance policies are broadly split into two types:

• Defined events policies — only cover specific listed events (storm, fire, flood, etc.)
• Accidental damage / full replacement policies — broader cover, but still with exclusions

Regardless of policy type, almost all insurers include exclusions for:

• Gradual damage (water ingress that has occurred slowly over time)
• Faulty workmanship or materials
• Lack of maintenance
• Pre-existing defects

If your waterproofing membrane on a deck, wet area, or basement fails and water has been slowly tracking in over months or years, your insurer is very likely to decline the claim on the grounds of gradual damage or maintenance failure. Always read your Product Disclosure Statement (PDS) carefully and speak directly with your insurer if you are unsure.

What Might Be Covered?

There are scenarios where insurance could respond:

The key distinction insurers make is sudden vs. gradual. A one-off event that causes immediate, visible damage stands a better chance of being covered than a slow failure.

The Contractor's Liability Angle

If a licensed or professional waterproofer did the work and it failed due to their error, you may have a claim against their public liability insurance rather than your own home insurance. This is why it is so important to:

• Always use a reputable, experienced waterproofing contractor
• Get a written quote and scope of work before any job starts
• Ask for proof of public liability insurance (adequate public liability cover is standard practice — confirm the level with your contractor and insurer)
• Obtain a written warranty on both materials and workmanship

If the contractor is a Licensed Building Practitioner (LBP), they are bound by a code of conduct and you have a formal complaints pathway through the LBP scheme. This matters a great deal when waterproofing is part of restricted building work — for example, waterproofing associated with a weathertight envelope on a multi-storey building.

NZ Building Code and Waterproofing Standards

Waterproofing in New Zealand must comply with the NZ Building Code, particularly:

• Clause E3 (Internal Moisture) — covering wet areas like showers, bathrooms, and laundries
• Clause E2 (External Moisture) — covering decks, balconies, and the building envelope

MBIE Building Performance publishes Acceptable Solutions and Verification Methods for these clauses. Work that does not meet these standards may not only void your insurance claim but could also create issues when you sell your home, as non-compliant work can affect a LIM report.

For wet area waterproofing, the relevant standard is NZS 4858 (Wet Area Membranes). Insurers and assessors may reference this when investigating a claim. BRANZ also provides technical guidance on waterproofing systems and is a useful resource for understanding best practice.

Protecting Yourself Before and After Waterproofing Work

The best way to protect your insurance position is to get the job done right in the first place:

• Use a qualified tradesperson — find experienced waterproofing contractors on tradedirectory.co.nz
• Check if a building consent is required — some waterproofing work (particularly on decks and balconies) may require consent; always confirm with your local council
• Keep all documentation — invoices, warranties, product data sheets, and photos of completed work
• Notify your insurer of significant building work — some policies require this
• Inspect regularly — check membranes, flashings, and sealants annually and after major storms

Using quality, proven products also matters. Reputable waterproofing systems from suppliers such as Ardex, Mapei, and Sika come with technical data sheets and application guidelines that, when followed correctly, provide a defensible record of compliant installation.

When to Call a Professional

Waterproofing failures can cause serious structural damage and mould issues that affect your family's health — a concern also reflected in the Healthy Homes Standards for rental properties. If you notice:

• Damp patches, staining, or bubbling paint on walls or ceilings
• Musty smells in bathrooms, under decks, or in basements
• Cracked or lifting tiles in wet areas
• Water pooling on a deck or balcony

…call a qualified waterproofing professional promptly. Delaying will almost certainly worsen the damage and reduce your chances of a successful insurance claim. You can find trusted local waterproofing contractors on tradedirectory.co.nz.

If you are unsure whether your situation is covered, contact your insurer first, then get an independent assessment from a waterproofing specialist or a building surveyor before undertaking any repairs.

Sources & Further Reading

• MBIE Building Performance — NZ Building Code
• BRANZ — Building Research
• Licensed Building Practitioners (LBP)
• Ardex NZ — Waterproofing Systems
• Sika NZ — Waterproofing Products
• Consumer NZ — Insurance Guidance