What Does a Building Project Really Cost?

What Does a Building Project Really Cost? Why ‘Cost Per Square’ Metre Doesn't Tell the Full Story

One of the most common questions we get at RP Builders is: "What's your cost per square metre?"

It's a fair question. People want a starting point, a ballpark figure to help them understand whether their dream build is realistic. But here's the honest answer: giving you a single square metre rate would actually do you a disservice.

Let us explain why.

Every Build is Different

Think about two 200sqm homes. One might be a single-level weatherboard home on a flat section with standard fittings. The other could be a two-storey concrete block build on a sloping site with high-end joinery and engineered timber beams. Both are 200sqm, but the cost difference could easily be $200,000 or more.

That's because building costs depend on dozens of factors:

• Your site conditions (slope, soil type, access)

• The design complexity (single level vs multi-storey, simple rectangle vs complex angles)

• Your material choices (cladding type, flooring, fixtures)

• The level of finish you're after

• Current market conditions for labour and materials
  

A square metre rate simply can't account for all these variables. It might sound like a helpful starting point, but it can actually lead to unrealistic expectations and budget blow-outs down the track.

How We Actually Work Out Costs

Instead of giving you a rough number and hoping for the best, we break our costing into stages that match where you're at in the planning process.

Preliminary Costing

If you've got concept drawings or initial plans, we can provide a preliminary estimate with a detailed breakdown. This gives you a realistic range based on what you're proposing. It's not a fixed quote at this stage, but it's detailed enough to help you make informed decisions about whether to proceed, adjust your plans, or revise your budget.

This early costing is really valuable because it means you're not spending thousands on detailed construction drawings and consent applications before you know whether the project is viable.

Final Pricing

Once your pricing plans and working drawings are finalised, we provide a fixed-price contract figure. This is typically presented as a lump sum, with prime cost (PC) sums included only for specific items where final selections are still to be made.

A Quick Note on Prime Cost Sums

You might come across the term "prime cost sum" or "PC sum" when looking at building contracts. This simply refers to an allowance for items that haven't been selected yet. While some builders rely heavily on PC sums, we prefer to work through your selections beforehand to give you the most accurate fixed-price contract possible.

Working Through Selections Before Construction

One of the ways we help keep costs predictable is by working closely with you during the pre-construction stage to nail down as many selections and finishes as possible. The more decisions we can make together upfront—your cladding, flooring, fixtures, joinery, colours, and finishes—the fewer variables and PC sums we need to include in your contract.

This approach means fewer surprises during the build, better cost control, and a smoother project overall. We'd much rather spend time with you making selections at the start than dealing with changes and variations once construction is underway. Why? Because changes mid-build often mean delays, additional costs, and the frustration of waiting for new materials to arrive while your project sits on hold. Getting it right from the start keeps your build moving, keeps costs where they should be, and gets you into your new home sooner.

How Payment Works

Your fixed-price contract is broken down into progress payments tied to stages or components of the build, depending on the size and complexity of your project.

For a standard residential build, we typically structure payments around build stages—site works, foundations, framing and trusses, envelope (roof and cladding), and so on. You pay as each stage is completed.

For larger or more complex projects, we might break it down into project components with payments based on percentages of completion. For example, a large-scale project might be divided into 15-20 components, making it easier to track progress and manage cash flow for everyone involved.

This staged payment approach means you're only paying for work as it's completed, and you can see exactly where your money is going throughout the build.

What's Included in Our Pricing?

One of our core values at RP Builders is complete project management, and that's reflected in how we price our work.

All our pricing includes everything needed to deliver your project smoothly and efficiently—project management, site deliveries, insurance, vehicles, site setup, health and safety compliance, admin, coordination of subtrades and materials, and all the behind-the-scenes work that keeps your build on track.

This comprehensive approach means you have a single point of contact and accountability throughout your build. We handle the complexity so you don't have to, ensuring your project runs efficiently from start to finish.

Let's Talk About Your Project

Rather than trying to squeeze your unique project into a one-size-fits-all square metre rate, we'd rather sit down with you and understand what you're actually trying to achieve.

Bring us your plans or ideas, and we can help transition them into reality. If you're still in the early stages, we work with trusted architects who can take your vision and turn it into buildable plans. From there, we'll talk you through what's involved, give you honest feedback on costs, and help you figure out the best way forward.

Because at the end of the day, your build deserves better than a guess based on square metres.

Ready to get started? Get in touch with the team at RP Builders to discuss your project.