How To Estimate The Costs Of Your New Build? [2024]

Before building a new home, adding an extension or adding any significant structure to your property, you need to estimate the cost. What costs are involved in building? Does a home extension cost more per square metre than a new build? Estimating the costs of your build will differ depending on the location, the quality of the work and other factors.

Estimating the Cost of a New Home

Surprisingly, the price of land may be higher than the cost of building a new home. Land prices in Australia have skyrocketed. At the same time, building costs have not risen as much. Of course, it may depend on where you're building. In Hobart, land is relatively inexpensive at around $223 per square metre. In Sydney, land is the most expensive in Australia at about $933 per square metre on average. The land you buy could be more or less expensive.

Building costs will also vary. The average cost of a new build in Australia is between $1183 per square metre (m2) and $1500m2. The average size of a home in Australia is 243 square metres. Using the average costs as a measure, the average cost of building a new home is between $290,000 and $365,000. Average costs can be deceiving. Other factors include:

• The building contractor's quote (some cost more than others)
• Location: some areas are more expensive than others
• The quality of the building
• Building materials
• Whether the block is level or sloping

The price per square metre does not include architect's or drafters fees, planning permits and other factors outside the cost of building. One of these factors is the land itself. Building on flat, easily accessible land is less expensive than building on a sloping block or a steep block. On average, building on a sloping block will cost up to 10 per cent more and building on a steep block can cost up to 20 per cent more than on a level block.

More expensive materials or an architect designed house with unusual features will cost more than average. It will depend on the project, but architect designed homes can range between $2100 and $5000 per square metre or even more.

Land prices will vary depending on the area. Building costs will also vary depending on the area. Here are some estimates of building costs in different areas:

• Adelaide: $1550m2 to $3400m2
• Brisbane: $1700m2 to $3400m2
• Canberra: $1530m2 to $2500m2
• Darwin: $1750m2 to $2750m2
• Melbourne: $1365m2 to $2700m2
• Perth: $1420m2 to $2263m2
• Sydney: $1550m2 to $4350m2

These are higher than the national average. In some regional areas, building costs are lower. Again, averages can be deceiving. One home may cost less or more than the average spread in any given area.

A two-storey house generally costs more per square metre than a single storey house. In fact, the difference can be as much as $80,000 to $100,000. This may depend on the materials used. For example, brickies charge more for a second floor than they do for a single storey home.

Another factor that will influence the cost of a new build is the quality of construction and inclusions. Whether you choose a budget, standard or luxury option, any home has to comply with Australian standards. The difference in price between a budget or standard home is not as high as you might imagine (around $10,000 on average), so get quotes for both.

If you want to save money on the cost of a home, look into kit homes. A surprising number of designs are available and some kit homes have high quality materials and components. Our article, Facts and myths about kit homes busts some common myths about kit homes. A kit home can be stylish and you can even add custom features to a kit home. Kit homes cost between $160,000 and $235,000 for a three-bedroom home. It can be less if you become an owner-builder.

The safest way to find out how much your new build will be is to find the land and have the home designed by an architect, drafter or look for a kit home design. Choose whether you want budget, standard or luxury inclusions and get quotes based on what you want.

Estimating the Cost of a Home Extension or Other Structure

Home extensions tend to cost more than new homes. There are several reasons for this. Builders tend to charge more for home extensions because they are not big jobs and can be finished relatively quickly. A home extension also involves some demolition work. A wall must be removed and the extension must fit seamlessly into the structure of the home. A typical home extension for a 10m2 room might cost:

• $57,000 to $68,000 for a budget room
• $119,000 to $143,000 for a luxury room
• $82,000 to $98,000 if a bathroom is included

These are estimates only, based on online calculators, which can be inaccurate. A home extension can cost much more than these prices. 10m2 is not a large room. Typically, home extensions cost between $100,000 and $300,000 depending on the size and inclusions. It will be on the higher end of the scale if:

• A bathroom is included
• A kitchen extension will cost more than a bedroom
• The extent of the demolition work
• Difficulty of access
• Whether the extension is on a flat or sloping block
• The standard of fittings: budget, standard or luxury

These prices do not include drafting or council fees.

Price blowouts are not uncommon in home extensions. The reasons for price blowouts can be:

• Not accurately pricing the inclusions
• Changing your mind about the design
• The cost of an architect versus the cost of a drafter

Ideally, a home extension should be treated like a new home. Finalise your design and stick with it. Choose the materials needed to build and fittings beforehand and consider having a drafter draw the plans instead of an architect. Architects tend to be more expensive than drafters. While architects can supervise a project, a home extension may not need their supervision unless it is a large or complex extension.

Home extensions cost more than other structures because they must be integrated into the existing home. Other structures might include a granny flat, gazebo or large shed designed to be a home office or work space. These smaller structures may cost more per square metre than a full sized home, but will be less expensive than a home extension because demolition work is not required..

If you need a home office, having it separate from the home will reduce the amount of noise coming from the home and clients will feel more comfortable in a separate space. While the word "shed" may sound like a small shed designed for storing tools, sheds today can be comfortable living or working spaces. 5 Top Shed Designs shows sheds from simple steel sheds to designer sheds.

A granny flat can be a good way to earn rental income. Check with the local council first to find out if a granny flat is allowed in your area. How Much Does a Granny Flat Cost? gives cost estimates for various kinds of granny flats. Like a shed, a granny flat can be a simple structure (as long as it has everything council requires) or a luxurious home.

Both sheds and granny flats also come in kit form or can be designed and built for you. Kits are generally less expensive than custom made sheds and granny flats, but even a kit building can be renovated to suit. As with new builds and home extensions, the cost of a shed or granny flat can vary. Get quotes from several builders and choose a granny flat or shed that suits your purposes.

Ultimately, every building project will have different costs. You can estimate the cost, but in the end, getting quotes will give a more accurate cost. Getting quotes costs nothing. You may need to make minor adjustments later, but getting quotes from several builders will give a better idea of the cost of building than an online calculator or a guess based on average prices.

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