🏡 Granny Flats: Your Guide to Building Without Consent

✔️ When You Can Build a Granny Flat Without a Building Consent

The granny flat building consent exemption allows you to build a standalone dwelling up to 70m² without applying for a building consent as long as all of the following are true:

You must:

• Use a Licensed Building Practitioner (LBP) to supervise design and construction. (This is non-negotiable; DIY doesn’t qualify.)

• Meet all Building Code requirements, even without council sign-off.

• Follow all district plan rules, including:

- Site coverage

- Height limits

- Boundary setbacks

- Private outdoor space

- Parking requirements (varies by council)

• Have connections for potable water and wastewater sorted legally (existing capacity OR new connection consented separately).

  
  

You can use it when:

• It’s a standalone, single-storey, self-contained dwelling.

• It’s less than 70m².

• It sits on the same property as an existing home.

• And the building materials are simple, such as timber and steel.

  
  

You can’t use the exemption for:

• Two-storey builds.

• Multi-unit developments (e.g., three 70m² units in a row).

• Major slope builds where retaining wall consents are required.

• Heritage zones, Character overlays, coastal hazard areas, or flood risk sites (may trigger extra consents).

• Turning it into a separate title; subdivision has its own rules.

  
  

💰 The Hidden Costs Nobody Talks About

Yes, you may skip the building consent fee… But that doesn’t mean your granny flat is “cheap.” Here are the big cost surprises owners are running into:

1. Development Contributions

Even without a building consent, councils can still charge development contributions (DCs). Expect this when your granny flat:

• Adds an additional household unit.

• Requires new water/sewer connection capacity.

• Increases demand on council infrastructure.

  
  

Typical DC ranges: $10,000 – $45,000+, depending on council. This is the cost most buyers are not planning for.

2. Infrastructure & Service Connections

Many sites need:

• New sewer line or pump system.

• Stormwater upgrades.

• Water main extensions.

• Additional capacity sign-off.

  
  

Expect $5,000 – $40,000+, particularly if you’re far from existing lines.

3. Planning & Checking Fees

Even without a building consent, councils can charge:

• Pre-application advice.

• PIM/LIM updates.

• Engineering review (if required).

  
  

Budget $1,000 – $4,000.

4. Driveway, Parking & Access

District plan rules may require:

• Additional off-street parking.

• Fire or service vehicle access.

• Vehicle crossing upgrades.

  
  

Budget $3,000 – $15,000.

5. Geotech, Drainage, or Retaining

If you’re on:

• Clay soils,

• Sloped sites,

• Flood-prone land.

  
  

You may still need:

• Geotechnical report.

• Drainage design.

• Engineered retaining wall.

  
  

These can easily add $5,000 – $50,000+.

6. Avoiding Consent = Higher Builder Standards

LBPs signing off their own work means:

• No “she’ll be right” shortcuts.

• More design documentation than most people expect.

  
  

✔️ Tips Before You Start

1. Check your zoning rules — overlays can kill projects early.

2. Do a service capacity check — water/sewer is the #1 budget blowout.

3. Budget for DCs even if you hope to avoid paying them.

4. Get multiple quotes; site prep varies wildly.

5. Talk to a planner early (not after you buy a prefab).

6. Think future-proofing: wider doors, flat access, flexible layouts.

   
   

🏁 Final Word

Granny flats may:

• Add value.

• Create options for family.

• Boost rental income.

• Help ageing parents stay close.

  
  

But “no consent” doesn’t mean “no rules” or “no costs.”

If you’re thinking about adding a second dwelling, talk early with:

✔︎ A planner

✔︎ A Licensed Building Practitioner

✔︎ Your council (for services + DC fees)

✔︎ Your real estate agent, especially if value uplift or resale is part of the plan.

🌟 Why Choose a Granny Flat?

Granny flats are more than just extra space. They can be a smart investment. Imagine having a space for guests, a home office, or even a rental unit. The possibilities are endless!

Flexibility and Functionality

Granny flats offer flexibility. They can adapt to your changing needs. Whether you want a place for family or a quiet retreat, they fit the bill.

Potential for Rental Income

With the housing market booming, a granny flat can provide rental income. This can help offset your mortgage. It’s a win-win situation!

Quick to Build

Granny flats can be built relatively quickly. This means you can start enjoying your new space sooner.

Conclusion

In summary, granny flats are a fantastic option for many homeowners. They provide additional space, potential income, and can increase your property’s value. Just remember to do your homework and plan accordingly. Happy building!