Granny Flats and Home Additions

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Granny Flats WA – Home Extensions & Renovations

Granny Flats WA is a Family owned and operated residential Building company having serviced the Perth metropolitan area for over 20 years.

Granny Flats WA has long been a trusted builder for Granny Flats in Perth, Western Australia, renovations and extensions. We have many years’ experience and know-how and we care about providing you with a beautiful finished product you can be proud of and enjoy.

Most people know that we build granny flats, but did you know that we also build renovations and extensions: from a small studio or office all the way to a complete home renovation to transform your 2 bedroom, 1 bathroom home into a 5 bedroom by 3 bathroom family home with pool and al fresco.

Of course we also build granny flats: we see them as micro homes in your back yard as we build them from concrete slab to finished structure. Every home is different and every home has differing privacy, lighting and existing structure particulars. Our trained Building & Design Consultants will listen to what your needs and wants are and can make an obligation free visit to your home to advise you on what will work best for your backyard taking into account all the circumstances of your budget and existing property layout.

Some clients like to build in stages. We can build a locked up structure for you with the necessary allowances for pre-lay plumbing so that you can elect when you wish to proceed with adding a bathroom, kitchen or laundry and decorating as your budget and needs require. Our experienced design consultants will ensure the any local council approvals are organised, too.

No doubt you’ve heard all about the changes to the laws recently allowing people to derive an income from renting out granny flats in their backyards. We have seen an increase in interest from investors and have some great stories.

Whether you are someone with with overseas relatives or friends, wanting a delineated home work space, a FIFO worker – or wanting rental income from a FIFO worker, wanting your parents or children to live close by, a granny flat or home improvement from Granny Flats WA can be your solution.

We have a showroom that showcase some of the granny flat designs and renovation options we can provide. We’d love you to bring your loved ones in and take a look around. We’re sure you’ll find it a very pleasant experience.

Granny Flats WA is a Family owned and operated residential Building company having serviced the Perth metropolitan area for over 20 years. We provide a tailored personal service including:


Design Consultation & Advice




Energy Efficiency




Council Submission through both Planning Department and Building Departments as required


Pre-Start Service


Quantifying, Ordering & Scheduling





FAQs about granny flats

How much do Granny Flats cost to build in Perth?

Granny flats can be built at a variety of price points depending on the size and specifications you choose. A budget one-bed investor specification granny flat can be built from as little as $79,000 move in ready. On the other end of the spectrum a granny flat can cost more than $275,000 for a designer, very large granny flat that has carports, garages, verandas etc.

Do you need planning permission for a granny flat?

Depending on how we design your granny flat or extension and the council you are in, you may need planning approval. This is all part of our included approvals process.

How long does a granny flat take to build?

For Granny flats up to 70sqm it would take approximately 10 weeks to build from slab down to complete including painting, floorcoverings, skirting boards, blinds and air-conditioning. Granny Flats WA will take care of all council approvals as part of the pre-process which will vary the time to build depending on local council approval processes.

What requirements are there to build a granny flat?

Under the standard R Codes, granny flats can be built on a single residential property over 450sqm in Western Australia. Considerations for setback and parking need be considered and in certain councils additional restrictions will apply.

Does a granny flat add value to your house?

Yes, granny flats add value to a home. The added value will be relative to the location, design and the state of the residential property market at the time.

Can granny flats be two storey?

Yes, we can build two storey granny flats. We have a range called our Fonzie Flat range as well as custom designs. The cost of a two-storey granny flat is much greater than a single storey with a starting price of $165,000 for a 40m2 unit with double garage below.

How much space do you need for a granny flat?

The minimum total block size required for a granny flat is 350m2. Our minimum recommended size for a liveable granny flat is 20m2 or 30sqm with a separate bedroom. A granny flat of this size would require an open space of 42m2 to have a 1 metre setback from each exterior wall.

How big can a granny flat be in WA?

In residential areas, the maximum size allowable for a granny flat is 70m2 as per the Residential Design Codes. On larger blocks and more rural areas, granny flats can be built up to a maximum size of 100m2. If for any reason you would like to build a granny flat in Western Australia bigger than these limits, with good reason, there are ways to go bigger.

What considerations need to be taken into account when building a granny flat?

Firstly a granny flat design needs to suit the purpose of the build whether it be for mobility, downsizing family or rental. Also designing to complement the existing residence avoiding clashing entertainment areas and windows looking directly to the existing home. This design service is provided free of charge after a showroom visit.

What is the difference between a studio, bedsit, and a granny flat?

Granny flats act as ancillary dwellings consisting of a bedroom, kitchen, and bathroom. Granny flats can either be freestanding or attached to the existing house. Studios and Bedsitters are granny flats with a bedroom, living area and kitchen in same open living space.

Can I convert a garage to a granny flat?

Yes, we can convert garage spaces to granny flats. As a rough guide a garage conversion has a similar cost to a freestanding granny flat but will require individual quoting depending on the existing structure.

How much rent can a granny flat generate in Perth?

Some present examples we have been notified of for rental are around $250/week for a single bedroom granny flat in Quinns Rocks. Again the net rental attained will be relative to location, number of bedrooms and finish. A 70sqm granny flat is the same living area as a new home on a cottage block. So, there is no reason the value of rent from granny flats would not be similar to that of same size houses in the same suburb.

What designs are available in the Granny Flats WA range?

As a specialist builder of Granny Flats we work with our clients to design bespoke builds suitable to each client’s needs. We do have several pre-designs from which we can adjust, however all designs are individual incorporating any special needs such as considerations for mobility or open plan one, two or 3 bedroom customised granny flats.

A lot depends on how much space you have – we can then offer a custom design.  All our granny flats are designed based on your needs.

We build in ranges, from the investor rental design or standard specification, right through to our executive apartment specification as shown off in our showroom in Booragoon (also our head office). We always suggest a showroom visit to view our granny flat designs and consultation prior to visiting the home. This will give you the best information for discussion when on site.

What kind of warranty or guarantee do you provide?

Granny Flats WA provides a 15 year structural warranty on the build of our pre-design and customised granny flats. All other aspects of construction as per building commission requirements of 6 years and individual items and appliances as per manufacturer.

Book an appointment for a free consultation.

Showroom Details

Based south of the river in Booragoon this show room offers
3 indoor granny flat displays.

Phone: 08 9329 6888

Address: 92 McCoy Street Booragoon


Open: Mon – Thursday : 10am to 4pm
             Friday 10am to 2pm
             Saturday 10am to 12.30pm

All other times open by appointment.


I have been most impressed with the dealings I have had with Granny Flats WA. The service I received and process of purchasing a granny flat was easy and well informed. Mike is very personable and lovely to deal with. He went out of his way to assist and meet my various requests and I have no hesitation in recommending him for his integrity, attention to detail and friendliness.

Belinda McClelland

Excellent from start to finish. Delivered exactly what we discussed. Our site Manager was always punctual and kept in touch, a pleasure to deal with. We are thrilled with the results of both our ensuite addition and renovation as well as our Granny Flat. Even nearly a year after the fact, if we have any questions or concerns they are quick to respond and always happy to help. Would not hesitate to recommend them, and would happily show our renovations and Granny Flat to anyone who was considering using GFWA.

Scott Fry

Fantastic we are so pleased with our room extension to our house. Dealing with this company has been a pleasure with everything delivered as promised on time and on budget All the tradesman were brilliant and easy to deal with and the Site Supervisor was great to deal with. Couldn't recommend this company more highly and both my wife and I are very very pleased.

Michael Webster

Just a big Thanks to you all. It is our second renovation with your company and dealing with your workman has been a pleasure, again. It is our first bathroom reno and by having your team well organised made it all go according to schedule and on price. We are saving up for the other bathroom now. I do appreciate receiving the product and service that we agreed upon.

Tony Mathers

Booragoon Showroom

92 McCoy Street, Booragoon, WA 6154
08 9329 6888

Mailing Address

PO Box 4459
WA 6960