Guarantees and warranties a waterproofer should offer in New Zealand

Why warranties matter when hiring a waterproofer

Waterproofing is one of those jobs where a small mistake can become a very expensive problem later. A shower that is not properly membrane-lined, a deck that has not been detailed correctly, or a retaining wall that lets water through can lead to damaged linings, rot, mould, and costly repairs. In New Zealand’s damp coastal climates and during heavy winter rain, poor waterproofing often shows up faster than people expect.

That is why it is not enough to ask, “How much will it cost?” You should also ask, “What is covered if something goes wrong?” A good waterproofer should offer clear warranties and stand behind their work in writing. Just as importantly, you should know what legal rights you already have under New Zealand law, because a contractor’s warranty does not replace your rights under the Consumer Guarantees Act (CGA).

The three layers of protection you should understand

When waterproofing work is done properly, there are usually three separate protections to think about:

A trustworthy contractor will explain all three, not just hand you a vague “guarantee”.

What a workmanship guarantee should cover

A workmanship guarantee is the contractor’s promise that their installation has been carried out properly. For waterproofing, this is often the most important guarantee because many leaks are caused by poor application rather than a failed product.

A sensible workmanship guarantee should state:

• the length of the guarantee
• exactly what is covered
• what is excluded
• how to make a claim
• whether the guarantee is transferable if you sell the property
• whether the contractor will inspect and repair at no extra charge if the fault is due to their work

For a typical bathroom membrane, shower, balcony, or deck waterproofing job, the contractor may offer a workmanship warranty anywhere from 5 to 10 years, sometimes longer. The exact length is less important than the detail in the wording. A long warranty that excludes everything is less useful than a shorter one that clearly covers defects in labour and installation.

Good workmanship guarantees often cover problems such as:

• membrane applied at the wrong thickness
• missed corners, junctions, or penetrations
• poor sealing around wastes, taps, or pipe penetrations
• insufficient laps, termination details, or fall to waste
• visible blistering, lifting, or cracking caused by incorrect installation
• leaks caused by failure to follow the manufacturer’s installation instructions

What a workmanship guarantee should not try to exclude

Be cautious if a contractor tries to exclude almost everything. In practice, some exclusions are reasonable. For example, a warranty will not usually cover:

• damage caused by later alterations or drilling into the waterproofed area
• structural movement beyond normal tolerances
• maintenance neglect, such as blocked drains or failing to reseal jointing over time
• damage caused by other trades after the waterproofing is complete
• misuse, flooding, or accidental damage

But the guarantee should not be so narrow that it becomes meaningless. For example, if the waterproofer is responsible for a shower membrane and it leaks because the membrane was installed incorrectly, that should be their responsibility to fix.

Ask them to be specific about what counts as “fair wear and tear” and what counts as a defect in workmanship.

Product warranties: useful, but not the same as a guarantee of the job

Many waterproofing systems rely on products from a manufacturer: liquid membranes, sheet membranes, sealants, primers, drainage layers, tile adhesives, and flashing materials. These may come with a product warranty, but it usually only covers defects in the product itself.

That means:

• if the membrane product fails because of a manufacturing defect, the warranty may apply
• if the membrane fails because it was not installed properly, the workmanship guarantee should apply

Do not assume that a manufacturer’s warranty means the installer has done the job correctly. A product can be excellent and still fail if the substrate preparation, detailing, curing time, or application method is wrong.

Before you sign a contract, ask:

• what brand and system will be used?
• is the product warranty conditional on installation by an approved applicator?
• will you receive the warranty documents after completion?
• are there maintenance obligations to keep the warranty valid?

If the contractor is using a proprietary waterproofing system, ask for the technical data sheet and make sure the proposed use suits the location. A shower, wet area bathroom, balcony, and roof deck are not interchangeable applications.

How the Consumer Guarantees Act protects you

The Consumer Guarantees Act 1993 gives you automatic rights when you hire a tradesperson for services, including waterproofing work. These rights apply whether or not the contractor offers their own guarantee.

Under the CGA, services must be:

• carried out with reasonable care and skill
• fit for the purpose you told the contractor about
• completed within a reasonable time, if no timeframe is agreed
• supplied at a reasonable price, if no price is agreed

If a waterproofer does a poor job, the CGA may require them to fix it. If the problem is serious and cannot be fixed within a reasonable time, you may be able to seek a refund, a price reduction, or damages for reasonably foreseeable loss.

This is important because some businesses use warranty language that sounds limiting, such as “guaranteed for 5 years only” or “no liability after completion”. Those statements do not remove your CGA rights in New Zealand.

Licensing, consents, and compliance still matter

A warranty is only useful if the work was lawful and compliant in the first place. Before hiring a waterproofer, check whether the project may need other regulated trades or council approval.

Key points for NZ homeowners:

• Building work may need a building consent from your local council, especially for significant alterations, decks, balconies, bathrooms, or structural changes.
• Plumbing, gasfitting and drainlaying are restricted work and must be done by appropriately licensed practitioners under the Plumbers, Gasfitters and Drainlayers Board (PGDB) regime.
• Electrical work is regulated and must be carried out by authorised persons under the Electrical Workers Registration Board (EWRB) framework.

A waterproofer may not be the person doing the plumbing penetrations, drain connections, or electrical work around underfloor heating or bathroom fixtures. Make sure each trade involved is properly licensed for the work they are doing.

Also ask whether the waterproofing system and installation method meet the relevant New Zealand Building Code requirements, particularly for wet areas and external membranes. If your job is part of a consented renovation, keep the paperwork because it may be needed for council sign-off or future property sales.

What to ask for in writing before the job starts

Do not rely on verbal assurances. Before work starts, ask for the following in writing:

• a detailed quote describing the scope of waterproofing work
• the product/system to be used, including brand names
• the length and terms of the workmanship guarantee
• any product warranty documents and conditions
• who is responsible for substrate preparation and who is doing related trades
• confirmation of any required building consent or code compliance steps
• the expected start and finish dates
• maintenance requirements to keep warranties valid

A good quote should also note any assumptions, such as whether tiles are being removed, whether rotten substrate will be repaired, or whether additional framing or drainage work may be needed once demolition starts. In waterproofing, hidden damage is common.

If a contractor will not put warranty terms in writing, that is a red flag.

Signs the guarantee may not be worth much

Some warning signs are subtle. Be cautious if you see any of these:

• the contractor avoids discussing warranty terms
• the guarantee is unusually short for the type of work
• exclusions are so broad that most practical faults are excluded
• the quote says “no liability for leaks” or similar wording
• they will not say what brand or system they are using
• they refuse to confirm licence or insurance details where relevant
• they suggest the work is “low-risk” and does not need formal documentation

You should also be wary of extremely low prices with little detail. Waterproofing failures are expensive to repair because the finish layers often have to be removed to access the membrane. In many cases, the cheapest quote is not the best value if the warranty and documentation are weak.

What recourse you have if the work is faulty

If you discover leaks, failed membranes, or other defects, act quickly. Water damage can spread behind walls, under floors, and into framing. Delays can make the problem worse and may complicate the warranty claim.

Practical steps:

1. Document the issue with dated photos and notes.
2. Stop using the area if continued use could worsen the damage.
3. Notify the waterproofer in writing as soon as possible.
4. Ask for an inspection and a repair plan.
5. Check the paperwork for warranty terms, invoices, and product details.

If the contractor accepts responsibility, they should normally return to inspect and remedy the defect. If they dispute the cause, you may need an independent assessment from another qualified professional, especially if the issue may involve substrate failure, adjacent trades, or council compliance matters.

If the contractor refuses to fix the problem, you may be able to rely on the CGA and seek a remedy. Depending on the facts, options can include:

• requiring the contractor to put the work right
• claiming the cost of remedial work from another contractor
• seeking a price reduction
• claiming losses that were reasonably foreseeable because of the faulty work

For larger disputes, keep all communication in writing and consider getting advice from the Citizens Advice Bureau, the Disputes Tribunal, or your lawyer if the amount is significant. If the claim is within the Disputes Tribunal’s jurisdiction, that can be a practical route for many homeowners.

How to compare quotes properly

When you get multiple quotes, do not compare only the bottom line. Compare the warranty and the detail behind it.

Look at:

• length of workmanship guarantee
• whether the warranty is backed by an established business
• product brand and installation system
• whether the quote includes preparation, primers, and sealing details
• whether council consent or inspections are included where needed
• evidence of insurance and licences relevant to the broader job
• references or examples of similar NZ work, especially in wet climates or coastal areas

It is reasonable to ask each contractor the same questions so you can compare like with like. A well-documented quote and warranty package often signals a more professional approach to the job.

The bottom line for NZ homeowners

A waterproofer’s warranty should do more than sound reassuring. It should clearly separate workmanship from product defects, spell out how claims are handled, and sit alongside your rights under the Consumer Guarantees Act. In New Zealand, where damp weather and building moisture problems can quickly become expensive, good paperwork is not a bonus — it is part of good trades practice.

Before hiring, get multiple written quotes, check that the right licences are in place for any restricted or regulated work, confirm whether council consent is needed, and insist on warranty terms in writing. If the work later proves faulty, document the issue, notify the contractor promptly, and use the CGA and your written contract to seek a proper remedy.