Why Your Builder's Quote Is Not Your Total Project Cost

What does a builder’s quote usually cover?

A builder’s quote generally covers the construction work and inclusions described in the proposal, specification and contract. Every builder structures those documents differently, which is why the total on the front page should never be read without the detail behind it. Some items may be included. Some may sit as provisional sums or prime cost allowances. Others may be excluded entirely.

Build Insight WA’s view: before comparing prices, make sure you understand whether the builders are pricing the same scope.

Which costs are commonly outside the headline contract price?

The exact list depends on the project, but common examples include:

• land purchase and settlement costs
• site works and earthworks
• energy-efficiency requirements
• bushfire or noise-related compliance where applicable
• prestart selections and upgrades
• landscaping
• driveways
• fencing and retaining
• window treatments, paths, letterbox and clothesline

Not every item will sit outside every builder’s contract. That is exactly why the specification and exclusions matter.

Why can two builder quotes be hard to compare?

Because the numbers may be based on different assumptions. One quote may include an item another excludes. One may carry a higher allowance for site works. Another may show a lower contract price but leave more for the owner to organise after handover. A cheaper quote can still become the more expensive project if the comparison is not being made on the same basis.

Build Insight WA’s perspective: when we compare builder proposals, the first job is often not choosing the cheapest one. It is making the documents comparable enough that the price actually means something.

What role do provisional sums play?

A provisional sum is an allowance for work that cannot be fully priced when the contract is prepared. If the actual cost is higher than the allowance, the owner generally pays the difference. That makes provisional sums one of the areas worth understanding before signing. The issue is not that provisional sums exist. They can be necessary. The issue is whether the allowance is realistic for the project in front of you.

Build Insight WA’s view: ask how each allowance was calculated and which ones are most exposed to change.

Why do site costs deserve special attention in Perth?

Perth blocks are not identical. Ground conditions, slope, access, retaining requirements, fill and other site-specific factors can all affect the work required before and around construction. That makes a generic site allowance less useful than one informed by the actual block.

Build Insight WA’s view: understand what information the site-cost allowance is based on before treating it as a reliable number.

How do you build a more realistic project budget?

Start with the builder’s contract price, then work through every other cost needed to get from the current stage to a completed project. A useful check is to separate the budget into three groups:

• costs before construction
• costs inside the building contract
• costs that still need to happen during or after construction

Then identify which figures are fixed, which are allowances and which are still unknown. You do not need to predict every variation. The aim is to understand where the budget still has uncertainty.

What should you check before signing?

• What is included in the specification?
• What is specifically excluded?
• Which figures are provisional sums or prime cost items?
• Are the site allowances based on your actual block?
• Which external works remain your responsibility?
• Are the quotes you are comparing based on the same scope?
• What contingency sits outside the contract price?

These questions help turn a headline contract price into a more useful whole-of-project view.

Where can independent review help?

Build Insight WA works on the client’s side of the building process. If you are comparing builder proposals, reviewing specifications or trying to understand the full cost of a project before signing, an independent review can help identify what is included, what is not and where the uncertainty sits. The aim is not to promise a saving. It is to help you make the decision with a clearer picture of the project.