House extension guide

You’ve got big ideas for the home of your dreams. More space for the family, better kitchen and bathroom, a room opening out into the garden. You could move house if your current house doesn’t meet your expectations, but the price of property in many areas of Australia continues to rise. And, with moving come all those fees to estate agents, lawyers, surveyors, plus the cost of a new mortgage and the disruption of moving.

If you do decide to move, you’ve got to find that ideal home in an area that might not have all the local facilities you currently enjoy and rely on – doctors, schools, gyms and parks. So, do you stay put or find an alternative?

Well, there’s one very suitable alternative – a house extension. Apart from giving you the features you really want, it could also add value to the property, which is great when you eventually want to move or sell up. By extending your house, you can create the home that meets your precise needs or your tenants’ needs, rather than accepting a compromise in a different property that’s almost there.

Planning a house extension: Make a list

Before you get into detailed planning for your house extension, make a wish-list. How many new rooms would you like to add? Will you need to add a new floor or basement, or could you convert space in the loft or garage?

Where will the new rooms fit in – side or back of the house – and how much space is available? Which existing rooms could you convert or extend? Do you want to add a secure porch at the front of the house, a spacious laundry room, or maybe a conservatory at the back of the house to make more of the garden?

That’s a great starting point, but now it’s time for a reality check! Do you really need all that new space and what are the real priorities — kids growing up and wanting their own space, elderly relatives coming to stay, kitchen and bathroom way too small for the growing family?

Then step back and ask if you can really afford it. You won’t be able to get accurate house extension costs until designs are finalised, but we will give you some indications later in the article.

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Get a detailed house extension design

When you’ve finalised your wish list, it’s time to get professional designs drawn up. An architect, interior designer or a renovation and extension company like Aireno can help you.

After discussing your ideas and explaining what can be achieved, a project manager and/or designer will visit your home and take detailed measurements as a basis for preparing plans. During the visit, the project manager can outline the scale of the work that will be needed and identify any potential problems.

The project manager and/or designer will also discuss style. The extension and all the fittings like doors, windows and brickwork should blend in with your existing home and be compatible with your existing architectural style, whether it’s modern, traditional or historical. If you have a period home or live in a conservation area, the designer can guide you through any regulations or restrictions.

The first thing you’ll see is a concept design – an ‘artist’s impression’ of how the extended building will look, plus an indication of room layouts. That helps you decide if the design really reflects what you had in mind.

When you’ve agreed on the concept, the designer will then prepare detailed plans for every aspect of the extension. These are essential for obtaining planning permission and giving guidance to builders and contractors for pricing and getting the work done.

As well as detailed floor plans and elevations, there will be plans for electrical and plumbing work and a list of all the materials needed to complete the project. Some of the work will also require structural calculations to ensure that the building is safe. The designer will ask a structural engineer to prepare those calculations and drawings.

Obtain permissions for your project

Before the project begins, you need to have permission from the local authorities. They will want to ensure that the planned work will comply with the Building Code and any other electrical or safety regulations.

They will also want to check that the new building will not interfere with the light or privacy of your neighbours, or have an impact on the appearance of the neighbourhood, particularly if it’s in a conservation area.

When the local authorities are satisfied, they will issue a planning permit to authorise work to start. As the project progresses, they are likely to carry out inspections at different stages to check that the work complies with standards and regulations.

Your chosen designer can handle the permitting process for you and negotiate any changes that the authorities might ask for. You can help the process along by talking to your neighbours about the plans and checking that they are happy with the designs and will not object.

How much does a house extension cost in Australia?

Now it’s crunch time when you find out what it will all cost. Builders and other contractors can only put together firm estimates when they have all the project details. It’s important to get several quotes to compare prices.

Some firms may offer an all-in one service and give you a package price. Others may work with subcontractors and give you prices from the various specialists. You could obtain prices from all the contractors yourself, but that can be very time-consuming.

Your designer can give you advice on suitable suppliers and vet the prices for you to ensure they represent value for money. As a guideline, Archicentre Australia suggests that extensions to existing buildings cost from $1,900 to $3,600 per square metre.

The final figure will be determined by the complexity of the project, with factors such as additions of new floors, special materials, site access, amount of demolition and removal of any hazardous waste. Your budget should also take account of any professional fees, cost of permits and inspections and decoration, furniture and fittings.

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Choose a builder for your house extension project

You’ve got a big choice here. You can either work with a company like Houseace that specialises in extensions and provides a complete service, or approach builders and contractors directly.

Any company you hire should be registered and certified with the appropriate trade association and be able to provide you with genuine references. Ideally, the builder should also specialise in extensions and have experience in any specific architectural style that you want. When you have chosen your suppliers, get contracts from them and a schedule of work so you know what will happen and when.

Manage the house extension project

If you’ve had other building work in your home, you’ll know that project deadlines can slip, contractors can’t make it on the scheduled day and late deliveries can leave the site team with wasted days.

That’s where a professional project manager can help by keeping suppliers and contractors on track. They coordinate everyone involved and can reschedule where necessary to minimise delays and ensure the project finishes on time. They will also monitor the quality of work and liaise with local authorities to arrange inspections. At Houseace, every project gets assigned their own expert project manager, whether it’s a small paint job or a large house extension.

While all the work is going on, you’ll need to consider how to manage your own life! There will be dust and noise for an extended period. Some important rooms like kitchens and bathrooms may be out of use while plumbing and electrical work goes on, and access could be difficult. But, when it’s all over and you’ve got the home you really wanted, you’ll find it was all worthwhile.

Help from Houseace

Our mission is to use technology to vastly improve and streamline the fragmented and disjointed home improvement process. We redefined the entire experience starting with a wide selection of high-quality services, customised online pricing and personal service on each step from setup to cleanup. Our tradespeople are the best in the business with years of experience, complete insurance coverage and all the required licenses and certifications.

Houseace is the simple, smart way to get your extension project done. Our easy-to-use platform allows homeowners to see their exact project price, including labour and material in minutes. And our dedicated personal service on each step makes the process to extend your home simpler and more transparent. Start your project today with an instant house extension quote, or use our renovation calculator to get an idea on cost and budget.

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Planning A House Extension: Everything You Need To Know – [2023]