Can you put a granny flat on a cross lease property?

The short answer

You can build a granny flat on a cross lease if your co-owners give written consent, the flat fits the exemption's size and setback rules measured against the whole cross lease site, and you update the flats plan afterwards so the title still matches what is on the ground. Council will not stop you and will not check your lease. Your neighbour can, if you skip the consent.

What a cross lease actually is

On a cross lease you own an undivided share of the whole piece of land, together with the other owners, and you lease the building you live in from all of the owners, including yourself, usually for 999 years. The lease comes with a flats plan that shows the footprint of each building and any exclusive use areas. That plan is part of your title and it is legally binding: what stands on the ground is expected to match it. Auckland Council puts the number at roughly 100,000 cross lease titles across about 40,000 schemes in the region.

The practical consequence is that you do not own your part of the section outright. You hold a lease over it, and the lease sets the rules, including when you need the other owners' agreement.

Why your neighbour's consent is the first question, not the last

Almost every cross lease includes a covenant that says you cannot make structural alterations or add new structures without the prior written consent of the other owners. A granny flat is a new structure, so the covenant applies. It applies even if the flat would be tucked in a corner the neighbours never see, because the test is in the lease, not in the effect on them.

Auckland Council is blunt about this on its own website: before any external construction on a cross lease property you need your co-owner's approval, and without it they can put a stop to your work. Council treats it as a civil matter between owners. It will issue your PIM, and in the past it has granted building consents, on the signature of one owner, because the Building Act only requires that the applicant is an owner. Council does not look at the lease. That means the paperwork from council is no protection at all if the consent from next door is missing.

Can they just say no? The 2026 Court of Appeal decision

Most leases say consent cannot be unreasonably withheld, and for thirty years the courts read that narrowly. Under a 1991 High Court case, Smallfield v Brown, a neighbour could refuse whenever the downside to them was more than trifling, which in practice gave them a veto over most change.

That changed in May 2026. In Liow v Martelli, a dispute between two Remuera owners over an extension, a pool and a deck, the Court of Appeal threw out the trifling test. The question now is whether a reasonable cross lease owner, acting jointly and weighing the interests of everyone on the title and the context of the development, could withhold consent. Genuine concerns still count: loss of light or privacy, noise, bulk, effect on value, or on the neighbour's own future plans. A blanket no does not.

For a granny flat this cuts both ways. A single storey building of 70m² or less, two metres off every boundary, with its own services, is a modest proposal, and a refusal that rests on not wanting change is now hard to defend. But a flat that blocks your neighbour's sun, sits hard against their outdoor area, or uses up the one minor dwelling the whole site is allowed is exactly the kind of thing a reasonable owner could object to. Which brings us to the planning rules.

The whole cross lease counts as one site

This is the part almost nobody knows. For planning purposes the Auckland Unitary Plan deems a cross lease to be a single site: the whole of the land under the cross lease, not your exclusive use area. The national standard that lets granny flats be built without a resource consent, the National Environmental Standards for Detached Minor Residential Units, allows one minor residential unit per site. On a two flat cross lease that is one granny flat between both of you, not one each. Whoever builds first uses it. A second one needs a resource consent under the Unitary Plan, which in the Mixed Housing zones is often still achievable, but it is a different process with a fee and a planner's assessment.

The site also sets the other numbers. Building coverage, capped at 50 percent for a permitted granny flat, is measured across the whole cross lease site with everyone's buildings counted. The two metre setbacks run from the outer boundaries of the whole site, not from the line of your exclusive use area, and the flat has to sit at least two metres from the house it belongs to. Your exclusive use boundary is a lease line, and the Unitary Plan does not see it.

One small mercy: the national standard switches off the Unitary Plan's amenity rules for a granny flat, so minimum outdoor living space, glazing and parking requirements do not apply to it. Rules about natural hazards, earthworks, infrastructure and subdivision still do.

The building consent exemption works on a cross lease, with one rule to watch

Nothing in Schedule 1A of the Building Act excludes cross lease land, so a granny flat that meets the exemption conditions can be built without a building consent on a cross lease exactly as it can on a freehold section. Council confirms the applicant is an owner, which a cross lease lessee is, and issues the PIM.

The condition that needs care is the two metre rule. The exemption requires the flat to be at least two metres from any legal boundary and from any other residential building. On a cross lease the legal boundaries are the outer boundaries of the underlying land. The other residential buildings include your neighbour's house. So the flat must be two metres from your house, two metres from theirs, and two metres from the outside edge of the whole site. On a tight two flat section that often decides where the flat can go before anything else does. The exemption also cannot be used for a building that straddles a boundary between separate allotments, which matters on the older cross leases that sit over more than one lot.

What happens to your title afterwards

A cross lease title is called defective when the flats plan no longer matches the buildings on the ground. There is no law that says you must update the plan, but banks, insurers and buyers behave as if there were. The problem usually surfaces at the worst moment: a sale, a refinance, or an insurance claim.

Whether a detached granny flat forces an update depends on the wording of your lease. Under the standard sale and purchase agreement, the trigger is a change to the exterior dimensions of the flat, which means something attached and enclosed, so a standalone building is not automatically caught. But most leases are stricter than the sale agreement, a new dwelling is a far bigger change than a shed, and a buyer's lawyer will want it on the plan. Our advice is to plan for an update from day one. It takes a surveyor to draw the new plan, a lawyer to vary the leases, the signatures of every owner and every owner's bank, and registration of the new plan and titles at Land Information New Zealand. Agree in your neighbour's consent letter who pays for it, because that argument is easier to have before the slab is poured.

Shared pipes, shared driveway

On most cross leases the driveway, the water supply and the drains are common property. Council's rule is simple: work on common property needs agreement from all the owners before it starts. A granny flat needs water, wastewater and stormwater, and on a cross lease those connections usually run through shared services. The exemption guidance, updated in October 2026, allows an existing connection to be altered to give the granny flat a secondary connection where the network operator agrees, and an existing on-site system to be used if it has the capacity. Watercare, or Veolia in Papakura, charges for new connections, not council. Get the drainage layout drawn before you ask your neighbour for consent, because the new drain crossing their side is the objection that ends most conversations.

What Auckland Council asks for, step by step

Auckland Council runs the granny flat exemption through a dedicated inbox and a project information memorandum, a PIM, rather than a building consent. On a cross lease the sequence looks like this.

1. Read your lease and get a copy of the flats plan from your lawyer or Land Information New Zealand. Note the alterations covenant and any exclusive use areas.
2. Call council's duty planner on 09 301 0101. Ask what the Unitary Plan zone allows on the whole site, whether a minor dwelling has already been built anywhere on the cross lease, and whether the land is flagged for flooding or other hazards.
3. Get the site measured: two metres from the outer boundaries, two metres from both houses, coverage across the whole site, truck access, and where water, wastewater and stormwater can connect.
4. Ask your co-owners for written consent that names the building, its position, who pays for the flats plan update, and who pays for any work on shared services. Get your bank's consent at the same time if the plan will change.
5. Apply for the PIM by email to GrannyFlatsBCExemption@aucklandcouncil.govt.nz with form 2AA, the licensed designer's form 2A, the plans, the location and external dimensions of the building, and how stormwater and wastewater will be dealt with. Put 'Schedule 1A small standalone dwelling exemption' in the subject line. The base fee is $537.
6. Expect a development contribution to be assessed through the PIM. Council charges them on granny flats. Water and wastewater connection charges come separately from Watercare.
7. Get any other approvals the PIM flags: network utility connections, a vehicle crossing if access changes, and anything that touches common property.
8. Build with licensed building practitioners doing or supervising the restricted work, and finish within two years of the PIM.
9. Within 20 working days of finishing, send council the final plans, the records of work and the electrical and gas certificates.
10. Lodge the new flats plan and varied leases through your lawyer and surveyor, then tell your insurer the new building exists.

Is it easier to convert to freehold first?

Converting a cross lease to fee simple titles is a subdivision. It needs a resource consent, a surveyor, a lawyer, every owner's agreement and usually every bank's, and it takes months. Some owners do it because it ends the consent question for good and lifts the value of both titles. It is not a precondition for a granny flat, and if the relationship with your neighbour is good, written consent and a flats plan update is the cheaper, faster path. If the relationship is poor, conversion will not be possible either, because it needs the same signatures.

What we do differently on a cross lease site

A standard SleekLiving site check already covers access, slope, hazards and services. On a cross lease we also measure the two metre rules to the outer boundaries and both houses, check the Unitary Plan zone and coverage on the whole site, and ask whether a minor dwelling already exists anywhere on the cross lease. We will not take a deposit on a cross lease job until the co-owners' written consent is in hand, because a build that has to stop halfway helps nobody. We can also point you to lawyers and surveyors who handle flats plan updates every week.

This guide is general information about Auckland, current to October 2026, not legal advice. Cross leases differ, and the wording of yours decides what consent you need. Have a property lawyer read it before you commit to anything.