How Long Does It Take To Build A Granny Flat? (with timeline)

Building a granny flat doesn’t take anywhere near as long as it takes to take to build a house. But it certainly does take some time, and if you’re in the market for a granny flat you are going to want to know exactly how long that is.

In general, it takes between 10 to 12 weeks to build a granny flat from scratch. This is just the build. And it doesn’t allow time for building sites that are slightly more complicated or require significant changes before the building work can even begin. It also doesn’t account for any delays due to weather or material shortages. Or the fact that you could spend many weeks or months planning and getting council approval before you can actually start.

The time spent on building a granny flat can be minimised if you plan appropriately. It would be wrong to assume that all granny flat builds will be straight forward. Some building situations are much more complicated than others and the various stages can vary significantly in duration. Keep reading to find out what those essential stages are!

Assess the site

Before jumping straight into the exciting idea of building your very own granny flat, it is important to first assess your land. Is your land in the state that will make it easy or even possible to build a granny flat?

The building and approval process could be made much more expensive and just difficult in general due to things such as:

  • Land incline or sloping.
  • Size and location of land.
  • Placement of sewage.
  • Stormwater drainage.
  • Current electrical work.
  • Existence of planning overlays.
  • Title restrictions.
  • Impact on surrounding neighbours.

When building a granny flat it is usually a good idea to consult a professional right from the assessment stage. It is hard for a layman to understand certain property limitations or regulations that may make the project much more expensive and difficult.

If you go ahead with the planning stage before first making the assessment, then you could be in for a rude shock. The cost of a planning mistake is much greater than the cost of taking the time out for a professional assessment.

Consider complying development requirements

If you want to make your life a little easier, consider the complying development restrictions for granny flats in your local area. Yes, this can be different according to where you live! It is still possible to have your granny flat approved if it falls outside of these guidelines, but it will be more difficult, and it will take much longer for approval to go through.

In NSW some of the general rules are: the property must be located in a specified residential zone, land must be at least 450 sqm and the granny flat size is set to a maximum of 60 sqm.

Whereas in Queensland, many areas allow granny flats of up to 80 sqm but it needs to be at least 20 metres from the main residence. The additional catch is, you cannot have the intention of renting to anyone outside of your household.

Many areas require an additional parking space for granny flat tenants. For even more specific requirements you will have to approach the friendly staff at your local council.

Make your plans

The next step, once you can answer yes to at least two of the following:

  1. a) You are blessed with a good block of land, that also won’t require too much prep work.   
  2. b) There are no specific government or neighbourly restrictions on your property.
  3. c) You can meet your local complying development guidelines or are happy to take on the challenge of submitting a full development application.
  4. d) It is still feasible and worthwhile to go ahead with the building.

You need to make a PLAN.

A complying development application will of course be much quicker and easier, so many homeowners choose to go down this path to granny flat ownership. Your granny flat design needs to be one that you will be happy with now and into the future.

Your design options can literally be endless, so it is important to discuss your needs with the designer so that the choice don’t become too overwhelming. With a granny flat build it is important to be smart with your space, you will be surprised how much you can actually fit into a little house of 60 sqm.

Council and Building approval

Once your plans are in place, it is time to take this to your local council for approval. If you have gone down the path of a complying development, this should get approved within a few weeks. A full development application (as explained previously) can take more time, sometimes even up to a few months.

Even after council approval is obtained, there is an additional step before getting started; building approval. You can get your building plans approved by using a private building certifier.

For all approvals it is important to use a professional who can help you with the specifics and paperwork required. It can be quite a confusing process and also very expensive if you get it wrong. Never start building without all the approvals in place, you may end up getting forced to start over.

Construction – 10 to 12 Weeks

First things first, make sure to warn your neighbours and all of those who will be affected by the building noise. This is a legal requirement in most cases. Construction can be loud and disruptive, conflicts can be avoided by having the courtesy to let people know and apologising in advance. The noise throughout the day can become quite an annoyance for a homeworker or mum with a young children trying to take a nap!

Step 1: Site preparation  

The first step before the actual construction can begin is the clearing & leveling of the land. This task is made much harder if there are many obstacles in the way. For example if you have a big clothes line that needs to be removed, or a landscaped garden that you will have to part with. The land needs to be completely clear and ready to build your new granny flat.

After the clearing, the builders will also have to prepare all the site connections. If this isn’t worked out in the beginning, you could find yourself with a very nice granny flat, but no lights or water!  Some of the connections that need to be considered are sewage, gas, electricals and stormwater.

Another thing to think about this at the first stage is access to the site for builders. Make sure there is sufficient parking and they are easily able to transport their materials onto the building site. If not, this could add a lot more time onto the project.

The construction workers should also have access to toilets and a lunch area. If it isn’t possible for them to come into your main residence, they may have to set up a temporary structure in the backyard. Thank god for the good old port-a-loo!

Step 2: Slab poured

Next up, pouring on the concrete. The beginning stages of construction will involve surveyors, who will mark the boundaries of your new granny flat. The slab will be poured and piers erected. A termite protection barrier is also important at this stage.

Already at stage 2, you will begin to see the shape of your granny flat.

Step 3: Build the the frame & then windows

The builders now move onto the frame, which is basically the skeleton of your granny flat. The frame will be put up for each and every room of the flat so now you will really start to see it take shape.

Step 4: Time to build the roof

Very quickly after building the frame, weather permitting of course, the builders will move onto the outside of the building. They will now enclose the granny flat with walls, and top that off with a roof. The building site is starting to look like home!

The time this takes can also vary according to your design and the materials you have chosen to use.

Step 5: Electrical & plumbing work is done

A fully enclosed granny flat now needs utilities. A plumber and an electrician should be on-site to make sure this is installed properly. If the granny flat is to be rented out to tenants, it is always a good idea to have a separate electricity meter.

Step 6: Insulation and plastering

The walls inside the granny flat are worked on further in this stage. Insulation of the interior walls is important to prevent excessive movement of heat, especially during the winter months.

The plastering is then done to finish off the job and put your new granny walls in the state that are ready for painting and decorating.

Step 7: External painting

Now we are ready to paint outside. How much work is required in this step does depend on the materials you have chosen. For example if your granny flat exterior is made of bricks, the only thing left to paint may be the window frames.

Step 8: Waterproofing & Flooring

Next, the builders will install your desired flooring and also make sure that the wet areas (such as the bathroom) are water resistant. If any carpeting is required this will be done at a later stage.

Step 9: Install major fitouts

Fitouts are a very important stage of the build, as who would want to live in a flat without a kitchen!? Also, it is specified that granny flats do need to be entirely self sufficient, so we can’t actually do away with any of the essentials.

The kitchen fitout is most likely the biggest job in this stage, followed by the bathroom fittings and also the wardrobes. A bedroom without a wardrobe can be tough to handle, especially in such as small living space.  

Step 10: Interior paint work and finalise fittings

Now time to make the interior look pretty and also add in any extras. The paint and paint colour you use to decorate can significantly impact the style of your granny flat, so it is important to carefully consider your choice here. At this stage, you may find it helpful to think about the furniture you will be using for the interior.

Step 11: Time to put in any carpets

One of the final steps of your granny flat build is to put in any carpeting. Obviously, if you don’t intend to have carpets, you can simply skip past this step. The reason the carpets are not done with the other flooring is because they can easily become damaged by the paint work and fitting work.

Step 12: Landscaping

For those who appreciate a garden, this step is important. Even minor landscaping work can make a big difference to your new granny flat. As it is now a huge feature in your backyard, you want to make sure that it is presented appropriately. You may like to install a walkway, some surrounding garden features or even a gate. The landscaping you add can really make a big difference to the feeling of your shared backyard space.

Step 13: Final clean up!

Once all is done there is, of course, the clean up. The builders will clean up any debris in the granny flat and in your yard that is left over from the work. Any temporary structures and equipment will be removed. And a cleaner will be sent in to help your granny flat shine!

Step 14: Maintenance and inspection

As with any other house or building, the maintenance and safety inspections are an ongoing process. Post build the inspections are of utmost importance as there is always the chance that something could have been missed in the build stage. A full inspection after the build is important to combat any teething problems that could arise.

Related questions

How much does it cost to build a granny flat? How much your granny flat will set you back cash wise will depend one quite a few factors; one of them being your design taste! In general, the cost for a granny flat build can vary between $50,000 to $150,000, and when making your decision it is important to ensure that you have covered all the costs in your estimation.

For example if the builder has come to you an quoted a price for the build, this may fail to take into consideration the planning and approval costs or any changes that need to be done to your land prior to building.

A prefabricated granny flat can be a cheaper option (and faster) for some people.

Can you get a home loan for a granny flat? As with any other type of home loan, your ability to get a home loan to finance your granny flat depends on a few factors. Namely, the banks confidence in your ability to pay back the loan.  This includes any other assets you have that would be able to be liquidated if the case came that you lost your job and where no longer able to make loan repayments.

The two key factors that influence your ability to get a loan for your granny flat are:

  • Your current equity in your main residence. If you own it outright then you are in with a big chance!
  • Your current income and assumed ability to make loan repayments.  

Taking out a loan to finance a granny flat that you will rent out is often a good move. The interest payments that you make on the loan will be deductible against the rental income that you will make from your new granny flat.

What is the average size of a granny flat? The average size of a granny flat is a one bedroom flat, that is between 50 sqm and 90 sqm in size. The council guidelines for most areas fall within this range, and it is easier to get approval when sticking to the guidelines. Some homeowners do opt to build a two bedroom apartment, and this is still possible to do so within the given space restrictions; you just need a good designer!

Does a granny flat add value? Sometimes it does and sometimes it doesn’t, but the added value could also be measured in non-financial terms. A granny flat build will not always add value to the property that is equal to or greater than the cost required to build the flat. Property value is measured by how much a buyer is willing to pay, and not all buyers may see huge value in having a granny flat.

On the other hand, a granny flat can bring a homeowner value in the lifetime of his property ownership via the rental income it can earn. It will take a while to earn back the initial investment, but once that is covered, the additional revenue is certainly a value add.

Granny flats also add value in the lifestyle options they allow for owners. They can provide space for teenage kids who need privacy, relatives who come to stay or even a private study or workspace.

Remember: A granny flat build could take some time

Your granny flat and your land is unique, and it is important to remember this when trying to come up with your project granny flat timeline. Right from the planning and approvals stage in the beginning, the variations will start to pop up. What might have been easy for Jack in the neighbouring suburb, may be very hard for your situation, and you will need to factor this in.

When it comes to actually working on the build, your particular requirements do play a big part. If you have your heart set on the most fancy kitchen there is to offer, then you might have to endure the builders for a little bit longer. When building your granny flat it is important to remember that old saying, good things do take time.

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