What Is a Granny Flat? Full Guide for Australian Homeowners

October 27, 2025

Granny flats are no longer just for grandparents. Across Australia, they’re being built as rental units, guest accommodation, or smart add-ons for multigenerational families. Climbing property prices and limited housing supply have made granny flats an attractive option for homeowners seeking flexibility and extra income.

Before you build, there are legal and planning steps to navigate. Each state has its own council rules, and the approval process can feel overwhelming. Prestige Homes & Granny Flats provides practical guidance on paperwork, design, and construction, keeping your project organised and on track from the start.

Before you start asking what granny flats are and how to build one, remember there are legal and planning steps to navigate. Each state has its own council rules, and the approval process can feel overwhelming. Prestige Homes & Granny Flats provides practical guidance on paperwork, design, and construction, keeping your project organised and on track from the start.

What are Granny Flats?

So what is a granny flat? The answer is simple. It’s a small, self-contained home built on the same block as a main residence. Think of it as a compact version of a regular house, usually including a kitchen, bathroom, living area, and one or two bedrooms.

Most states cap their size at around 60 m², though exact limits vary. In Queensland, they’re often called “secondary dwellings,” while in Victoria, you’ll hear “dependent person’s unit.” No matter the name, the idea is the same: extra living space with independence built in.

What Are Granny Flats Called in Perth?

Across Perth and the wider WA region, granny flats are formally classified as “ancillary dwellings” under local council planning regulations. They’re permitted on most residential-zoned blocks that meet the minimum land size, with a maximum floor area of up to 70 m².

A major difference in WA is who can occupy them. Since 2015, Perth’s rules have allowed ancillary dwellings to be rented to non-family members, giving homeowners more flexibility for rental income or family use. Councils such as the City of Perth, City of Stirling, and City of Joondalup apply these state planning guidelines, though it’s always worth checking your local council’s requirements before starting.

In Perth, granny flats can take several forms. They may be built as a detached unit, joined to the main house, or created by converting existing structures like garages. This flexibility makes them an appealing way to add space, boost property value, or create rental income without leaving your current suburb.

What Is Granny Flat: Legal and Planning Rules You Need to Know

To fully understand what granny flats are, you also need to follow council regulations that vary from state to state.

Zoning and Land Use

Your block must be in the correct residential zone to allow an ancillary dwelling. Perth councils set these rules, so it’s important to confirm land use requirements before drawing up plans.

Size Limits & Design

In most parts of Australia, granny flats are limited to 60 m². In Perth and wider WA, ancillary dwellings can be up to 70 m², provided they meet council design codes for height, setbacks, and appearance.

Approval Processes

Some states require both planning and building permits, while others fast-track approval if certain criteria are met. In WA, approvals generally move faster when plans follow the Residential Design Codes (R-Codes).

Rental & Occupancy Rules

Unlike some states, Perth homeowners can lease ancillary dwellings to non-family members. Since the 2015 policy change, this flexibility has allowed granny flats to serve as either rental income properties or extra family space.

Benefits of Building a Granny Flat

When people ask what granny flats are, the answer often lies in the many advantages they bring. From extra income to more living space, they are a smart choice for modern homeowners.

Dual-income potential

A granny flat can be rented out to provide a steady income. It is a simple way to make your property work harder for you.

Flexibility for growing families or elderly parents

Families gain extra space without the cost of moving. Elderly parents or adult children can live independently while staying close.

Boosts property value

Secondary dwellings often increase a property’s resale value. Buyers see them as a smart investment with ongoing benefits.

Can serve as guest accommodation, office, or studio

Beyond family use, granny flats can double as a guest house, home office, or creative studio. Perth homeowners are also using them as quiet retreats for study or remote work.

Eco-conscious and space-efficient solutions

Smaller homes require less energy to run. They are a practical choice for reducing costs and environmental impact.

Steps to Build a Granny Flat in Perth/WA

Understanding what is a granny flat is only the first step. Building one involves more than choosing a design, as each stage ensures your project is compliant, practical, and ready for use.

Understand local council rules

Check with your council to confirm zoning and land requirements. This prevents costly delays later in the process.

Select layout and design (custom, prefab, or conversion)

Choose between a custom build, a prefabricated unit, or converting an existing space, as each option comes with different costs and timelines.

Secure planning/building approvals

Most projects need formal approvals before construction can begin. Submitting accurate plans helps speed up the process.

Engage licensed builders

Work with professional builders who specialise in granny flats. Prestige Homes & Granny Flats ensures quality construction and reliable service.

Prepare for family use or rental management

Decide how the granny flat will be used once complete. Set it up for relatives, or get rental systems in place for tenants.

Why Choose Prestige Homes & Granny Flats?

If you’ve been searching for answers to what is a granny flat and how to build one in Perth, the process comes down to understanding council rules, approvals, and design choices. This can feel overwhelming without the right guidance, which is why expert support makes all the difference.

At Prestige Homes & Granny Flats, we handle everything from design advice and council approvals to full construction with certified builders. Our team delivers practical, well-finished custom homes and granny flats that fit your property and lifestyle. Whether you’re chasing rental income, family space, or a property value boost, we can make it happen.

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