AUSMAR blog

Why Two Custom Homes the Same Size Can Cost Completely Different Amounts

Written by admin | June 11, 2026

Acreage, waterfront, sloping or suburban - discover why square metre rates rarely tell the full story when it comes to custom home costs.  

One of the most common questions custom home builders hear is:

"What's your square metre rate?"

It's an understandable question.

When you're trying to budget for a new home, having a simple number feels like the easiest place to start.

The challenge is that custom homes don't work like most products.

Two custom homes with exactly the same floor area can have vastly different construction costs. In some cases, the difference can be significant.

So if size isn't the biggest factor, what is?

The Block Often Has the Biggest Influence

A 300m² home on a flat suburban block will have very different requirements to a 300m² home on a steep hinterland site, acreage property or waterfront allotment.

Before a custom home can be accurately priced, factors such as the following need to be understood:

  • Site slope
  • Soil conditions
  • Site access
  • Existing retaining walls
  • Flood overlays
  • Bushfire considerations
  • Existing structures
  • Proximity to neighbouring properties
  • Coastal conditions

These factors can influence everything from engineering requirements to construction methods and material selections.

That's why understanding the block is often the first step in understanding cost.

The Construction Method Matters

Not all homes are built the same way.

The construction method required for one project can be very different to another depending on the design and site conditions.

Factors such as:

  • Timber framing
  • Steel framing
  • Structural steel requirements
  • Suspended slabs
  • Retaining structures
  • Engineering solutions

can all influence the overall investment required to bring a custom home to life.

While these elements may not always be visible once construction is complete, they often play a significant role behind the scenes.

Materials Can Change Everything

Two homes may look similar in size on paper, but the materials selected can create very different outcomes.

External finishes such as:

  • Brick
  • Render
  • Cladding
  • Feature stone
  • Roofing materials

can all influence construction costs.

The same applies internally, where selections made throughout kitchens, bathrooms, flooring and joinery can significantly alter the overall specification of a home.

This is why custom homes are rarely comparable based on floor area alone.

The Design Brief Makes a Difference

No two families live the same way.

Some homeowners prioritise entertaining. Others want dedicated workspaces, luxury retreats, multi-generational living or strong indoor-outdoor connections.

Before any meaningful pricing can occur, a builder needs to understand:

  • Accommodation requirements
  • Lifestyle priorities
  • Special features
  • Design inspiration
  • Interior preferences
  • Future plans for the home

These decisions influence not only the size of the home but also the complexity of the design and level of finish.

Why Square Metre Rates Can Be Misleading

Square metre rates can be useful as a broad planning guide.

However, they don't account for the unique combination of site conditions, design requirements, engineering solutions and material selections that make every custom home different.

A simple custom home and a highly detailed architectural home may share the same floor area, yet have completely different construction requirements.

That's why relying solely on a square metre rate can often create unrealistic expectations.

The Real Question Isn't "What's the Price Per Square Metre?"

The better question is:

"What factors will influence the cost of my home?"

Once the block, design brief and project requirements are understood, builders can begin providing meaningful guidance around budget and design outcomes.

Until then, any number is simply a rough estimate.

Because when it comes to custom homes, size is only one piece of the puzzle.

Ready to Start the Conversation?

Every custom home begins with understanding the land and the lifestyle it's being designed around.

Whether you're building on acreage, a waterfront block, a sloping site or an established suburban lot, our team can help you understand the opportunities and considerations that may influence your project.

Book a complimentary site assessment and speak with our custom homes team to start exploring what's possible for your block.