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Building your dream home is an exciting adventure, but it’s also a costly one. The biggest mistake we see people make when planning their home is underestimating just how much a build is going to cost.

A budget for a new home needs to incorporate everything from the actual build cost to GST and consultant fees, so it can often balloon out from initial numbers. Here’s an explanation of all the expenses you need to consider and what other factors may influence the end number.

When first starting out on the construction journey, we generally gauge a building’s costs by estimating the size, quality and level of difficulty. These elements act as a guide for feasibility, but are then complemented by aspects like time frames, site access, site conditions, technology and sustainability. If it’s an architecturally designed home you’re after, additional factors include architect fees, the level of detail and complexity of structure.

In order to fit budget constraints, some of these factors may need to be eliminated. While it may seem that everything is completely necessary, the reality is that we can assist in determining priorities, providing guidance on what is achievable and appropriate. For example, if space is the absolute priority, you may have to compromise on time, opting for a longer construction process with less tradespeople. The same can be said for the reverse – if time is of the essence, size may need to be adjusted.

Here are just some of the main points affecting building costs:


The larger the house, the more materials, labour and equipment are required. Depending on time frames, it may also require a larger team. Therefore, it may be worth re-considering at plan stage where the emphasis lies – are you creating space for space’s sake, or taking advantage of every nook and cranny to create innovative spaces?

At Construct Central Coast we are open to working with clients and their chosen designers/architects to review plans in order to reduce building costs.


The best quality materials, finishes, and fittings are naturally going to be more expensive, but this is due to more than just the raw materials themselves. Better materials demand better finishing and craftsmanship and the labour costs increase proportionately. A builder who understands how things work will be required in order to schedule works properly and provide adequate protection to the materials, both during and after installation. At Construct Central Coast, we believe in only investing in quality finishes and fittings and will not compromise quality for cost.


Features that are designed to help make a space look larger or increase the amount of natural light can significantly add to costs. Voids, split levels, open plans, and spaces that connect cleverly together often require complex structural designs that are harder to conceive and assemble and often use different materials.

However, this doesn’t mean you are condemned to a home of conventional design. You can be economical in elements like skirting, cornices and architraves, as well as standard door and window sizes. These are very easy to source, universally understood and are small details that won’t be noticed by the majority of people who walk through your door.


A project’s time frame is usually influenced by the number of people on site – the more people, the more hands on deck to get the job done. That said, having a large team doesn’t automatically mean the work will progress faster. This is one of the key elements when choosing a builder – you must ensure every individual has the correct experience and is able to work with the wider team effectively and efficiently.

Variations throughout the build can also have a significant impact on time frame. Last minute changes often cause disruption to scheduling and the added time on site results in added build costs.


Builders need good access for delivery, storage and use of machinery. A tight inner-city site or renovation project will be a costly logistical challenge. Sloping blocks also present challenges and it’s not uncommon for build costs to increase by as much as 30% where the slope is steep. The soil conditions and surrounding environment also affect the type of foundations and if you hit rock while excavating, the costs will blow out even further.

Furthermore, building on or near a boundary shared with another building or trees requires more complex forms of support and protection. This is why most build and construct type display homes are only possible on regular, flat blocks. If the site has inherent complications, you need a good architect to make it work or risk blowing out the budget considerably.


Technology should always be considered a luxury, especially with the sheer range of choice of modern smart systems. Swimming pools, basements, home theatres and lifts are all items that many of us want but don’t realistically allow for when calculating cost. A basic rectangular swimming pool, for example, might start at $60,000 and seem affordable, but when you add in the pool fence, cover and heating, the cost can easily double. On top of this, add designer tiles, an infinity edge, a spa, a little more length to allow for laps, and what once was cheap is now very expensive.


With the minimum energy rating in New South Wales now at six stars, it’s almost impossible to escape double glazing and insulation, which have increased average building costs in recent years. Hydronic heating and off-grid power sources from solar or geothermal energy are not cheap and few clients will extend their budgets to accommodate these, despite the long-term benefits. Incorporating recycled materials can also prove troublesome as they can be difficult to source and implement, as well as being more labour intensive.

So what exactly does it cost to build?

Experienced architects and builders can discuss a project in brief and have a gut feeling for the overall costs, usually within 20% of the actual amount.

For the average person, however, it is unfortunately very hard to calculate build costs without involving a quantity surveyor or other professional cost estimator. As a very rough guide, we will assume an average build cost per square metre. Note, however, that this can only be a rough guide as the cost per square metre to build a basement or garage will differ vastly from the cost per square metre of a kitchen.

At Construct Central Coast, we have range in houses averaging around $1million + GST to projects in excess of $6million + GST.

From our experience, it is unrealistic to have a fully architecturally designed home that falls below a build cost of $2,500 + GST per square metre. These projects usually feature durable materials that look fantastic and feel contemporary, are readily available and easy enough to install. With regards to design, the brief should be met with a floor plan and look that is reasonably unique and contemporary. Such a house could not be overly complex in structure or build. Luxury extras would need to be minimised.

Unfortunately, $2,500 + GST per square metre does not go far and most clients at Construct Central Coast opt for designs that allow between $3,500 + GST and $4,500 + GST per square metre. Our top end homes in categories 4 and 5 will impress in every aspect and can cost anywhere from $5000 + GST to $10,000 + GST per square metre. Note that these figures are for the build only.

Other costs to allow for are:

  • Luxury items such as swimming pools or smart technologies.
  • Landscaping and fencing which could easily require a further 15%.
  • Any demolition of existing buildings, removal of asbestos, and other site preparations or protections
  • All consultants and costs for permits and approval


  • A 300-square metre house built at $3,000 + GST per square metre = $900,000 + GST
  • Site conditions: for a significantly sloping block with limited access, allow an extra 10% = $90,000 + GST
  • Luxury items: for a heated swimming pool with cover and self-cleaning capability, allow an extra $100,000 + GST
  • Landscaping and fencing: allow an extra 15% = $135,000 + GST
  • Existing house demolition and site preparation: allow an extra $20,000 + GST
  • Architect’s fees including interior design: allow an extra at 12% of $1,115,000 = $138,600 + GST
  • Other consultants and fees: allow an extra $20,000 + GST.

TOTAL BUDGET ALLOWANCE = $1,363,600 + GST= $1,499,960

From the above example, we can see that someone with $1 million wanting a 300-square metre house might assume that they are ready to proceed, but after considering all factors, they might in fact be almost half a million dollars short.

Therefore, it’s worth taking the time to discuss every element of your home with your builder before you begin. This will allow for any potential issues to be flagged at the beginning of the project and ensure that costs are kept as close to budget as possible.

To find out more, or organize a chat with our expert team, get in touch today!