It is the first question almost everyone asks, and the honest answer is that the headline rate matters far less than what sits underneath it. Two 60m² granny flats on two Auckland sections can differ by tens of thousands of dollars without a single difference in the building itself.

Here is what actually moves the number, so you can read a quote properly rather than comparing two figures that were never measuring the same thing.

The build itself is the predictable part

A self-contained minor dwelling is a small house. It needs a kitchen, a bathroom, a laundry, insulation, glazing, cladding, a roof and a full set of services — and most of those cost close to what they would cost in a large house. That is why the per-square-metre rate on a small dwelling looks high next to a full home build: the expensive rooms make up a much larger share of the floor area.

As a rough guide, a well-specified granny flat in Auckland generally lands somewhere in the $2,800 to $4,200 per square metre range for the building work, depending on specification and access. Treat that as a starting point for a conversation, not a quote — the site is what decides where you sit in that band, and sometimes whether the band applies at all.

The site is where quotes really differ

The cost of getting services to the building, and getting machinery to the site, is the single biggest source of variation we see.

• Distance to services. Power, water and wastewater have to reach the new dwelling. A flat ten metres from the existing connections is a very different job from one at the back of a long section.
• Access. If a digger and a concrete truck can get to the pad, groundwork is straightforward. If everything has to come through a side gate by wheelbarrow, the labour cost climbs quickly.
• Ground conditions. Sloping sites, fill, clay and high water tables all mean more foundation. Auckland has plenty of all four.
• Wastewater capacity. An existing connection may need upgrading to take a second dwelling, and that is a line item people rarely see coming.
• Trees and retaining. Protected trees, retaining walls and level changes each add cost and sometimes add consent.

Does the 70m² exemption make it cheaper?

Partly, and not in the way most people expect. The standalone dwelling pathway can remove the building consent step for a single-storey granny flat up to 70m², which saves consent fees and the time that goes with them. What it does not remove is the Building Code. The dwelling still has to be built to standard, by the right people, with the records to prove it.

It also does not override your local planning rules. Whether your site can take a second dwelling at all — and where it can sit, how tall it can be, how much of the section it can cover — is a separate question from building consent, and it is the one worth answering first. We check that before anyone spends money on plans.

The costs people forget to budget

• Site works, excavation and spoil removal
• Service connections and any wastewater upgrade
• Development contributions, where they apply
• Driveway, path and parking for the new dwelling
• Landscaping and reinstatement once the build is finished
• Fencing or screening for privacy between the two dwellings

None of these are optional extras. They are simply the parts that do not appear in a per-square-metre rate, which is exactly why a rate on its own is a poor way to compare builders.

What to ask for in a quote

Ask for a fixed scope in writing, with the site works itemised separately from the building. Ask what is excluded. Ask who carries the risk if the ground turns out to be worse than expected, and ask what the process is for a variation. A quote that is a single number with no breakdown is not cheaper — it is just less clear about where the extras will come from later.

If you are weighing up a minor dwelling on your section, we will assess the site, tell you which consent pathway applies and give you a fixed-scope quote before you commit to anything.

Most people choose a tradesperson under pressure. Something is leaking, a tenant is complaining, or a settlement date is closing in, and the decision gets made on whoever can come first. That is understandable, and it is also how the expensive mistakes happen.

A little structure at the start saves a great deal later. Here is what is worth checking.

Check the licence, not just the logo

Restricted building work in New Zealand has to be carried out or supervised by a Licensed Building Practitioner. That covers most structural work, weathertightness and anything that touches the building envelope. You can search the public LBP register yourself, and it takes about a minute.

Trade association membership — Master Builders, New Zealand Certified Builders, the Association of Professional Builders — is a useful signal on top of that, because those bodies have standards to maintain and a complaints process behind them. It is not a substitute for the licence, though.

Read the quote, not the number

The most common reason a job costs more than expected is that the cheap quote never included the whole job. Before comparing prices, check that both quotes describe the same work.

• Is the scope written down, item by item?
• What is explicitly excluded?
• Who pays for disposal of the old material?
• Is scaffolding or access gear included?
• What happens if something is found once the wall is opened up?
• Is it a fixed price or an estimate, and does it say so plainly?

A quote that is longer and more specific is usually the cheaper one by the end.

Ask how variations are handled

On repair and maintenance work, surprises are normal. Rot behind cladding, a failed membrane under tiles, a waste pipe that was never connected properly — none of it is visible when the quote is written.

What matters is the process. A good contractor stops, shows you the problem, prices the extra work and gets your agreement in writing before continuing. If someone tells you variations “just get sorted at the end”, that is the single clearest warning sign in this trade.

Understand what the guarantee actually covers

Ask three questions: what is guaranteed, for how long, and who honours it if the company is not around. Workmanship guarantees and product warranties are different things, and the product warranty is often void if it was not installed to the manufacturer’s specification.

For residential building work, the Building Act implied warranties apply whether or not anyone writes them down, and the Consumer Guarantees Act sits alongside them. A contractor who is comfortable talking about all of this is telling you something useful.

One point of contact beats five

On anything that touches more than one trade, the coordination is most of the job. If you are managing the plumber, the electrician, the tiler and the painter yourself, you are the project manager — and you are the one absorbing the cost every time one of them turns up to find the previous trade has not finished.

A single contract with one point of contact costs a little more on paper and usually less in practice, because the gaps between trades are somebody else’s problem.

The questions worth asking

• Who will actually be on site, and are they employed or subcontracted?
• Can I see two recent jobs like mine?
• What is the payment schedule, and what is the deposit for?
• What are your health and safety arrangements on an occupied property?
• How do you protect the rest of the house while you work?
• What does the site look like at the end of each day?

None of these are difficult questions for a competent contractor, and the way they are answered tells you most of what you need to know.

If you would like a written, itemised quote for maintenance or repair work anywhere in Auckland, we are happy to provide one at no cost.

Almost every expensive repair we are called to in July started as something small and cheap in March. Water is patient — it finds the one unsealed joint, the one blocked outlet, the one lifted tile, and it works on it all winter while nobody is looking.

None of the following takes long. All of them are cheaper than what happens if they are skipped.

1. Clear the gutters and downpipes

A blocked gutter overflows behind the fascia rather than in front of it, which means the damage happens to the timber you cannot see. Clear the leaves, flush the downpipes, and check the water actually gets to the ground.

2. Check the roof for lifted or cracked material

You are looking for slipped tiles, lifted sheet edges, rusted fixings and anything sitting proud of the line. From the ground with binoculars is fine — nobody needs to be on a wet roof to spot the obvious.

3. Look at the flashings

Most roof leaks start at a junction, not in the middle of a sheet. Chimneys, skylights, vents, valleys and the joint where a roof meets a wall are where to look first.

4. Treat moss and lichen

Moss holds water against the roof surface and slowly lifts tiles as it grows. Treating it is inexpensive and adds years to the roof; leaving it does the opposite.

5. Reseal the shower

Silicone around a shower tray has a life of a few years, and grout cracks as a building moves. Both are a morning’s work. A shower leaking into the floor for a winter is a bathroom rebuild.

6. Check the extractor fans actually vent outside

A fan venting into the roof space is worse than no fan at all — it moves the moisture from a room you use into a cavity you never see. For rental properties, venting outdoors is a Healthy Homes requirement, not a nice-to-have.

7. Clear the subfloor vents

Garden beds, stacked firewood and new paths block subfloor ventilation surprisingly often. A damp subfloor shows up as cold floors, musty smells and, eventually, borer and rot.

8. Walk the drainage

Find where the stormwater goes. Check the gully traps are clear and above ground level, look for pooling against the foundation, and make sure a new deck or driveway has not redirected water towards the house.

9. Check exterior joinery and seals

Perished seals around windows and doors let in both water and heat. Run a finger along the rubber, look for gaps at the head flashing, and check that the drainage slots at the bottom of aluminium joinery are not painted over or blocked.

10. Look at the deck and the fence before the wind does

Push the handrail. Check the posts at ground level where rot starts. A loose baluster in March is a repair; the same baluster in a August storm is a liability.

If you would rather not go up the ladder

All of the above is work we do every week across Auckland, usually as one visit rather than ten separate call-outs. We will give you a written condition report with photographs, tell you what genuinely needs doing now, and be honest about what can wait another year.