Keeping warranties alive

Most of the expensive parts of a property carry a warranty: the roof, the joinery, the deck membrane, the heat pump, the paint system, the hot water cylinder, and the builder's workmanship. A warranty is a contract with conditions, and many of the conditions are about maintenance. It stays alive only while they are met, and a claim is a bad time to find out which ones were missed.

Three layers of protection

1. The Building Act. All residential building work carries implied warranties, whatever the contract says and whether or not there is a written one. Among them: the work is done in a proper and competent manner, with reasonable care and skill, to the plans and any building consent, and in line with the law, and the products used are suitable for their purpose and, unless the contract says otherwise, new. They cannot be contracted out of. You can take action on them for up to 10 years, and a later owner of the property can rely on them too. For the first 12 months after completion there is also a defect repair period: tell the builder in writing about a defect, and they must fix it within a reasonable time.

One clause matters most here. A builder is not liable for a defect to the extent it was caused by a failure to carry out normal maintenance, or by repairs not being done as soon as practicable once the problem showed. Even the strongest protection you have assumes the house was looked after.

2. The Consumer Guarantees Act. Goods you buy as a consumer, including appliances fixed into the house such as a heat pump or a cylinder, must be of acceptable quality, and that includes being as durable as a reasonable consumer would expect. Services must be carried out with reasonable care and skill. These guarantees keep applying after a manufacturer's warranty runs out, a business cannot contract you out of them, and your first stop is the business that sold you the product. The Act does not cover a whole building, and it won't help if a failure came from using the product in a way no reasonable owner would. It is also why an extended warranty sold at the counter often adds little.

3. Manufacturers' and installers' warranties. These are written promises on top of the law, and they come with conditions. A manufacturer's warranty usually covers its own product, often not the installation, the rest of the system, or the damage a failure causes. Some apply to the original purchaser only, which matters the day you sell.

What your builder must hand over

When residential building work is finished, the law requires the builder to give you:

• copies of any current insurance policies they hold for the work;
• copies of the guarantees and warranties for the materials and services used, including how to claim, whether they transfer to a new owner, and whether they must be signed and returned to be valid;
• information on how to maintain the work, where maintenance is needed to meet the Building Code's durability requirements or could affect a warranty.

A licensed building practitioner must also give you a Record of Work for any restricted building work they carried out or supervised, and an electrician must give you a Certificate of Compliance for fixed wiring work. If you never received these, ask now. They are far easier to get this month than in year seven.

What quietly voids a warranty

• Missed maintenance. Pre-painted steel roofing and cladding needs hand-washing wherever rain doesn't reach: for COLORSTEEL, every six months in a moderate environment and more often in harsher ones. Powder-coated joinery needs a regular cleaning programme. Heat pump warranties commonly put filter cleaning, a clear drain and an unobstructed outdoor unit on the owner, and some require an annual service.
• The wrong method or product. Warranties say how to clean. NZ Steel specifies water with a sponge or soft nylon brush, or a water blaster at limited pressure. Dulux warns that non-approved solvents can cause damage that takes up to a year to show. The wrong cleaner can be a breach in itself.
• A form never returned. Some warranties only count once a form is signed and returned or the product is registered. Your builder has to tell you which. Do it the week the product goes in.
• The wrong installer. Many products are warranted only when fitted by an accredited installer: Rinnai's heat pump warranty requires a Rinnai accredited installer, and Dulux's powder coat warranties require a Dulux accredited powder coater. Restricted building work must be done or supervised by a licensed building practitioner.
• Someone else's work on top. A bracket screwed through the roof, a heat pump fixed to the cladding, a deck bolted into the wall. Each can take that part outside its original warranty. Ask the manufacturer or the original installer before anyone fixes into a warranted surface.
• The wrong environment. A coastal site needs products and protection rated for it. One major heat pump warranty excludes corrosion where protection suited to the site was not specified, applied or maintained.
• No proof. A claim starts with proof of purchase and the installation date. Without an invoice there is no start date.

The paperwork to hold

1. Invoices. Supply and installation, dated, naming the product and the installer.

2. The warranty document itself. With its conditions, not just the certificate.

3. Proof of registration. Or the signed and returned form, where one is required.

4. Compliance documents. The code compliance certificate for consented work, the Record of Work, and the electrical Certificates of Compliance.

5. Photos of the installation. Especially anything later covered up.

6. A maintenance log. What the warranty required, when it was done, who did it, what they used, and the invoice if a trade did it.

The sixth answers the first question anyone asks when something fails: was it looked after?

Make the conditions a schedule

The day a warranty starts, read its maintenance conditions and turn each one into a dated job: wash the sheltered parts of the roof and cladding, wash the joinery, service the heat pump if the warranty asks for it, recoat the deck when the stain calls for it. Done and logged, each job is a line that answers a claim before anyone questions it. In your record, the warranties sit with their invoices and photos, you add their conditions to your care schedule, and each job is logged as it is done. The paint and finishes guide has the wash cycles for the common exterior finishes.

What to do when something fails

1. Photograph it before anything is moved or repaired.
2. Tell the right business in writing, promptly: the builder for building work, the seller for goods, the installer or manufacturer for a written warranty, as it directs.
3. Stop the damage spreading. A defect made worse because nobody acted on it is not the builder's to carry.
4. Send the invoice, warranty and maintenance log with the claim.

If it becomes a dispute, building.govt.nz and consumerprotection.govt.nz set out the next steps.