Should I get an attached or detached granny flat?

An attached granny flat and a detached granny flat can both be good for different circumstances. Attached granny flats are linked to the structure of the main home, meaning they save space and let you keep your loved ones closer. Detached granny flats are free standing, which means they provide greater privacy for potential occupants. While the approval requirements are similar between the two options, their designs do noticeably vary.

What is an attached granny flat?

An attached granny flat is built onto the structure of an existing property. Attached granny flats share at least one wall with a house, much like home extensions. This makes it possible to convert existing rooms into attached granny flats. Garages are a popular choice for such conversions since they tend to be spacious and easy to repurpose. If you don’t have a suitable room, granny flats can attach to the edge of your house and use the space in your backyard.

In practice, attached granny flats function much like duplexes. They are linked to the main house but function as entirely independent dwellings. However, unlike a duplex, a granny flat can not be sold separately from the main house.

What are the benefits of a house with an attached granny flat?

A house with an attached granny flat has several important benefits. Opting for an attached granny flat makes better use of the space on the lot. This is incredibly valuable when you’re building on a smaller block of land. The space you save can be utilised to make the granny flat larger or add other features to your property.

Attached granny flats are uniquely suited to being residences for elderly parents. They allow homeowners to be closer to their loved ones and put them in a better position to provide support. Incorporating accessible granny flat design takes this a step further to accommodate elderly occupants.

What is a detached granny flat?

Detached granny flats are built on a property but not directly connected to the main residence. For this reason, they are also known as free standing granny flats or stand alone granny flats. Their independent building structure gives them greater separation, making them feel like their own small houses. This is reflected in their building process, which uses similar steps to a house build. While room conversions are possible for detached granny flats, it’s not common for suitable structures to be available. More often, they are built from scratch in a house’s backyard. 

What are the benefits of a house with a detached granny flat?

Houses with detached granny flats bring various benefits for homeowners. Detached granny flats are separated from the main house, offering greater privacy to both homeowners and potential tenants. This makes them more desirable as rental properties. The added privacy also makes them better for repurposing as offices or hobby rooms. Since these rooms are used for specific tasks, the greater seclusion makes concentration easier. If your detached granny flat is on the smaller side, it may work well as an office pod.

Counterintuitively, detached granny flats are often cheaper to build than attached granny flats. This is because attached granny flats must seamlessly fit into their corresponding house. As a result, structural changes are required to ensure proper insulation and minimal leakage. These can quickly rack up the overall building costs. Detached granny flats are usually built from the ground up and avoid this issue.

Wooden veranda on the outside of a yellow granny flat

Attached vs detached granny flat requirements

Attached and detached granny flats have similar requirements for getting their designs approved. Either option will require the appropriate building approvals. When it comes to size requirements, attached granny flats conform more easily. Being linked to the house saves space that detached granny flats need to use for setbacks. On the flipside, attached granny flats must seamlessly blend their exteriors into the primary residence. Detached granny flats still need to match the house’s style, but may have a more distinct appearance.

Granny flats must have features that allow them to be self-sufficient. Utilities such as water and electricity must have their own sources. This is to ensure that occupants aren’t reliant on the primary residence. Similarly, attached granny flats must have separate entrances to the primary residence. Passing through the main house should not be necessary to access the dwelling.

Attached vs detached granny flat design

Attached and detached granny flat designs have different considerations to keep in mind. The influence of the primary residence, the need for privacy and the aesthetic choices are all important factors.

The primary residence

Both attached and detached granny flat designs must be congruent with the main house. The requirements are more stringent for attached granny flats, since they share a structure with the main home. This is mainly a concern for the outside of the granny flat, which is readily visible. Interior décor isn’t subject to these restrictions.

The primary residence also affects how easily attached granny flats can be incorporated. Certain features, such as skillion roofs, are much more suitable for integrating a granny flat. Because of this, designs will fit more easily with certain houses.


The occupants of a granny flat are entitled to a certain level of privacy. Detached granny flats are better for this, due to their separation. However, there are other aspects to take into account. Orientation makes a significant difference. Facing a granny flat and its windows away from prying eyes lets residents feel secure and safe. Landscaping may be utilised to a similar end. Shrubs and bushes are good at mitigating lines of sight that could negatively affect the privacy of tenants.


Aesthetic considerations for granny flats are primarily a matter of preference. You may incorporate features that appeal to you or that appeal to prospective renters. For the interior, you are able to choose between open plan and closed plan layouts, the number of bedrooms and materials you want. These give the granny flat personality and make it feel unique.

For the exterior, there are many potential additions that spruce up your yard. Patios, decks and verandas are all great additions to a granny flat. They have the added benefit of having separate size limits. This means they won’t cut into the size limits of the interior. Attached granny flats tend to have more room for exterior additions.

Both attached and detached granny flats are excellent choices when you’re looking to add another dwelling to your property. Whatever you choose, you want it to be built to a high standard by a trusted builder. Granny Flats WA has over 20 years experience helping people build the granny flats that suit them best. Contact us now to request a quote or have a chat.