How to Read a Building Quote and Compare Two Fairly
Why the lowest number is frequently the most expensive, the six things to check line by line, and the questions that expose an incomplete price.
Two quotes are rarely comparable
Owners routinely put two builders' numbers side by side and pick the lower one. That comparison only works if both quotes cover the same scope, priced on the same information, with the same assumptions about the site.
In practice they almost never do. One builder may have a soil test and a survey; the other may have an assumption. One may include the driveway; the other may not. One may carry a realistic tiling allowance; the other may carry one no real tile meets.
So the useful skill is not comparing totals. It is working out what each quote actually contains.
1. What site classification was priced?
Ask each builder what site classification under AS 2870 the footings were priced to, and whether they have a soil test for your block.
If the answer is an assumption, the largest single cost variable in the project is unpriced, and the quote is provisional regardless of what the heading says. Reactive clay across South East Queensland means the difference between a conventional slab and an engineered footing runs into tens of thousands.
2. What is in the site works?
Earthworks, retaining, drainage, service connections, demolition and site access. Ask whether these are fixed items or allowances, and what basis was used — a contour survey, or an eyeball.
Ask specifically whether concrete pumping has been allowed for and on how many pours. On a sloping or narrow block that is a real recurring cost.
3. Provisional sums and prime cost items
Count them and read what each covers. A handful of specific allowances is normal. Broad allowances covering most of the site work mean the price is not fixed in any meaningful sense.
For prime cost items, go and look at what the allowance actually buys before signing. An allowance no real product meets is a deferred increase, not a saving.
4. What is excluded
The exclusions list is the most informative page in most quotes and the least read. Driveways, landscaping, fencing, window furnishings, letterboxes, clotheslines and appliances are commonly excluded.
A quote that excludes the driveway and one that includes it are not comparable, and the difference is not small.
5. Payment stages and the deposit
Check the deposit is within the 5 per cent cap that applies to Queensland domestic building contracts over $20,000.
Then check the progress payment stages are proportionate to the work completed at each point. A front-loaded schedule leaves you exposed if the job stalls.
6. What happens when something changes
Ask how variations are priced and approved, and confirm they will always be documented in writing before work proceeds.
Ask what the defects liability period is, and confirm QBCC home warranty cover for your job specifically.
A builder confident in their pricing will answer all of this without hesitation. Our guide to site costs covers what turns an advertised price into a real one.
Ask for the quote to be broken down
A single lump sum tells you nothing about what is inside it. Ask for a breakdown by trade or stage — site works, footings and slab, frame, roof, external cladding, services, internal fit-out, external works.
That breakdown lets you compare two quotes meaningfully and shows you immediately where they differ. It also reveals whether a low quote is genuinely more efficient or simply missing scope.
A builder who has priced your job properly can produce this without difficulty, because they built the number that way. One who cannot is telling you something.