The Real Cost of Choosing the Cheapest Builder
What gets left out of a low quote, and where the real cost shows up.
Why quotes look different when they aren't
A building quote is only as comparable as the specification behind it. What's included, what's excluded, and what's been estimated as a provisional sum all determine the real cost of a project. And these are exactly the places where a low quote creates room to look competitive on paper.
Provisional sums are placeholder figures for items that haven't been fully specified yet, things like joinery, tiling, stone benchtops, or landscaping. A builder who sets these low gets to show a lower total. When those items are actually selected and priced, the gap closes fast. By the time the build is finished, the "cheap" quote may have grown to meet or exceed the others, but by then, you're already contracted and committed.
Exclusions work similarly. A quote that doesn't include site preparation, waste removal, engineering reports, or certain finishes looks smaller. It's only when those items are quoted as variations, mid-build, when you have limited leverage, that the true cost becomes visible.
What gets cut to hit a low number
To price genuinely lower than the market and remain profitable, something has to give. This usually shows up in one of three places.
The first is trades. Cheaper builders work with cheaper subcontractors. On a straightforward volume build this matters less. On a bespoke architectural project, where the joiner needs to deliver custom cabinetry, where the plasterer is working to a render specification, where the tiler is cutting to a pattern, the quality of the trade directly determines the quality of the result. Rectification work on a premium finish is expensive, time-consuming, and sometimes impossible to make invisible.
The second is supervision. A builder's margin isn't profit for nothing. It covers the principal's time on site, coordination between trades, procurement relationships, and the knowledge that comes from experience on projects of that complexity. A builder running too many projects at too thin a margin can't afford to be on yours.
The third is time. Builders who underprice work to win it often find themselves carrying a project that isn't profitable, which means resources get directed elsewhere. Timeline blowouts are expensive for homeowners, in temporary accommodation, in carrying costs, in the cascading stress of a build that isn't moving.
The warranty and insurance question
In Victoria, any residential building work over $10,000 must be carried out by a registered building practitioner. For work valued at $16,000 or more, that builder must also take out Domestic Building Insurance (DBI) before starting. DBI protects homeowners if a builder becomes insolvent, dies, or disappears before completing the work, or if defects emerge after handover.
An unregistered builder, or one operating outside the legal framework, offers a lower price in part because they're not carrying the cost of registration, insurance, or compliance. The homeowner absorbs that risk entirely. If something goes wrong, there's no insurance to call on and no regulatory body to pursue.
Checking registration is straightforward, the Victorian Building Authority maintains a public register. If a builder isn't on it, the low price reflects that omission.
How to read a quote properly
The question to ask of any quote isn't just what the total is, it's what the total includes.
Ask for a breakdown of provisional sums and what they're based on. Ask what's excluded and how variations would be handled. Ask what the specification covers for finishes, materials, and trades. Ask whether DBI is included and at what stage it's taken out.
A builder who provides clear, detailed answers to these questions is giving you the information you need to make a real comparison. One who doesn't is leaving you to discover the gaps later, when you're already on site.
The Impact Build position
At Impact Build, we don't aim to be the cheapest quote. We aim to be the most accurate one, and to make sure that what we quote is what gets built, without the variations and surprises that turn a "cheap" build into an expensive one.
That means clear specifications, honest provisional sums, and conversations about budget that happen before the contract is signed rather than after. It means being a registered building practitioner with appropriate insurance in place. And it means taking on projects where we know we can deliver to the standard the client and the design deserve.
The builds we do aren't for everyone. But for the clients they're right for, the cost of getting them right is considerably less than the cost of getting them wrong.
A low quote tells you what a builder is willing to say. A detailed quote tells you what they're actually going to do.
Planning a project in the Macedon Ranges?
If you're comparing quotes and something doesn't add up, it's worth having a conversation before you commit. Understanding what's in each number, and what isn't, is the clearest way to know what you're actually signing up for.
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