The Granny Flat Boom: What the New 70m² Rules Really Mean for Your Property

Granny Flats Under 70m² in NZ: What Kitchens, Bathrooms, and Real Build Costs Look Like.

The new granny flat rules in New Zealand have opened the door to some exciting opportunities. They make it easier and faster to add a small, self-contained dwelling to your property, whether that’s for family, extra income, or long-term flexibility.

But with that excitement has come a bit of confusion.
Many people now assume a granny flat is a “quick, cheap” solution. In reality, it’s better described as a smart, streamlined way to build a proper small home.

The rules reduce red tape, not responsibility.
You still get a high-quality dwelling that’s safe, compliant, insurable, and built to last.

This is great news for people who want to do things properly.

The facts 

Size & Form

• Single-storey, standalone dwelling, max 70 m² floor area.
• Maximum height around 4 m with floor level ≤1 m above ground

Design & Construction Requirements

• Must have a simple design that fully complies with the NZ Building Code (H1 energy/thermal performance still mandatory).
• Construction & design must be by Licensed Building Practitioners (LBPs), architects or equivalent certified professionals. 

Council Notification

• Builders/homeowners must notify their local council before starting and after completion of the build.
• A Project Information Memorandum (PIM) is still required to trigger the exemption and infrastructure check

Site & Planning Rules Still Apply - Even with consent exemptions, district plan standards must be met

• Setbacks, boundary distances (often ~2 m), site coverage, recessions, and zoning.
• Natural hazard overlays, heritage or landscape restrictions may still trigger a resource consent.

Infrastructure Contributions (water, wastewater, roads, etc.) can still apply and are typically collected via the PIM process.

Insurance & Finance:

• Even without formal consents, proof of compliance may be needed for lending or insurance.'

Renter & Tenancy Law:

• Granny flats built under the exemption still must comply with the Residential Tenancies Act and Healthy Homes standards if rented.

What Is a Granny Flat Under 70m²?

A granny flat under 70m² is a self-contained residential dwelling.
It’s not a sleepout or a minor add-on. It functions exactly like a small home.

That means it includes:

• A kitchen
• A bathroom
• Legal plumbing and drainage
• Electrical compliance
• Ventilation
• Insulation and thermal performance
• Connection to water and wastewater systems

The building consent exemption simply removes one layer of process.
It does not change the quality or compliance standard.

Bathroom Rules (Made Simple)

Bathrooms in granny flats follow the same principles as any residential home.

At a minimum, you need:

• A toilet
• A hand basin
• Hot and cold water supply
• Connection to approved wastewater systems

If you add a shower or bath:

• Waterproofing must meet NZ Building Code standards
• Mechanical ventilation is required
• Flooring must be moisture and slip-resistant
• Drainage must be professionally installed

Other important points:

• Plumbing must be completed by a certifying plumber/drainlayer
• Hot water systems must meet safety regulations
• Moisture control is essential for durability and insurance

Think of it as building a normal bathroom, just in a smaller footprint.

Kitchen Rules (Made Simple)

A self-contained granny flat must have a functioning kitchen.

At minimum:

• A sink with potable water
• Wastewater connection
• Space for cooking appliances

If you include:

• Cooktops or ovens → mechanical extraction is required
• Electrical appliances → electrician's sign-off is required
• Gas appliances → certified gasfitter and safety certification required

Additional considerations:

• Backflow prevention devices may be required
• All plumbing must comply with G12 and G13 of the Building Code

Again, this is normal residential kitchen infrastructure, just scaled down.

What Still Applies Even Without Building Consent

This is where clarity matters most.

Even under the 70m² exemption:

• Council must still be notified before construction
• Council must still be notified after completion
• Councils still check:
  • Water supply capacity
  • Wastewater capacity
  • Stormwater impact
• Development contributions may still apply
• District Plan rules still apply:
  • Setbacks
  • Height limits
  • Site coverage
  • Zoning and overlays

The system is simpler, but it’s still structured and accountable.

A Realistic View on Cost

Granny flats are popular because they offer:

• Faster approvals
• Lower professional fees
• A smaller overall build than a full home

But they are still:

• Proper residential builds
• Using licensed trades
• Built to national standards

This makes them a strong long-term investment rather than a short-term shortcut.

Where Sheds Fit In (And Where They Don’t)

Steel buildings are brilliant for:

• Storage
• Workshops
• Garages
• Utility buildings

But turning one into a compliant dwelling means:

• Full insulation upgrades
• Plumbing infrastructure
• Waterproofing systems
• Ventilation compliance
• Fire and moisture separation
• Council notification
• Trade certification

At that point, you are no longer building “just a shed.”
You are building a house inside a steel structure.

That changes the cost and complexity.

Why Doing It Properly Pays Off

A compliant granny flat gives you:

• Easier insurance approval
• Better lending options
• Legal rental capability
• Strong resale value
• Peace of mind long-term

It protects your asset and future-proofs your investment.

The Takeaway

The new granny flat rules make building easier.
They make planning faster.
They make small dwellings more accessible.

What they don’t do is remove the need for:

• Budgeting
• Professional trades
• Council engagement
• Compliance

That’s a good thing.
It ensures every granny flat built is safe, durable, and commercially sound.