Prime Cost Items and Provisional Sums Explained

If you're reviewing a building quote or contract, there are two terms you need to understand before you sign:

Prime Cost Items and Provisional Sums.

They might look like ordinary numbers in your contract, but they are not necessarily fixed prices.

They are allowances.

And if those allowances are too low, your final building cost can increase — sometimes significantly.

Understanding prime cost items and provisional sums before signing a building contract can help you compare builder quotes more accurately, set a more realistic budget and avoid unpleasant surprises during construction.

Here's what homeowners need to know.

What Is a Prime Cost Item?

A Prime Cost Item, often shortened to a PC item, is generally an allowance in the building contract for an item that has not yet been specifically selected, or whose actual price is not known when the contract is signed.

Common examples can include:

• Tiles
• Tapware
• Toilets
• Basins
• Baths
• Kitchen appliances
• Door hardware
• Light fittings
• Other fixtures and fittings

Queensland's building regulator describes a prime cost item as an item such as a fixture or fitting that has not been selected, or whose price is not known, when the contract is entered into, with a reasonable allowance made for its supply and delivery.

A Simple Prime Cost Example

Imagine your building contract includes:

You later visit the tile supplier and choose tiles costing $65/m².

That means the original allowance may no longer cover your selection.

The difference can affect the final amount you pay, and depending on your contract, other amounts such as the builder's margin, delivery costs or GST may also need to be considered.

This is why homeowners should never look at a PC allowance and assume:

It's better to think:

Those are two very different things.

What Is a Provisional Sum?

A Provisional Sum, often shortened to a PS, is an estimated allowance for particular work where the builder cannot reasonably determine the exact cost when the building contract is signed.

Queensland guidance describes a provisional sum as an estimate for contracted services where the builder, after making reasonable enquiries, cannot state a definite amount when the contract is entered into.

Examples might include:

• Excavation
• Rock removal
• Site works
• Retaining work
• Certain drainage works
• Unexpected ground conditions
• Some landscaping works
• Work dependent on information that isn't yet available

The important distinction is that a Prime Cost Item usually relates to an item or selection, while a Provisional Sum usually relates to work or services where the final scope or cost is uncertain.

Prime Cost Item vs Provisional Sum: What's the Difference?

Here's the easiest way to remember it:

Both can change the amount you ultimately pay, which is why they deserve close attention before you sign.

Why Prime Cost Items and Provisional Sums Matter

PC items and provisional sums are not automatically a problem.

Sometimes an allowance is genuinely necessary.

The issue is whether the allowance is realistic.

Consider two builders quoting the same home.

At first glance, Builder A appears to be $20,000 cheaper.

But what happens if the homeowner ultimately wants $60/m² tiles, $8,000 worth of appliances and the site works actually cost $25,000?

The gap between the two quotes suddenly looks very different.

This is one reason comparing building quotes based only on the headline contract price can be misleading.

You need to understand what has actually been allowed for inside each quote.

The Danger of Unrealistically Low Allowances

One of the biggest questions homeowners should ask is:

If you're building a premium home but your contract contains entry-level allowances for flooring, tapware, appliances and bathroom fixtures, you could face substantial additional costs when it comes time to make your selections.

The same principle applies to provisional sums.

If an uncertain piece of work is allowed at an amount well below its realistic cost, the initial contract price can look more attractive than the eventual project cost.

Official consumer guidance recommends minimising PC items and provisional sums where possible because they create uncertainty around the final contract price. Queensland's standard contract documentation similarly notes that these allowances should be kept to a minimum to reduce uncertainty.

Don't Just Look at the Total — Look at the Allowance

Imagine your contract says:

Ask yourself what that $5,000 is actually expected to buy.

For example:

• Oven?
• Cooktop?
• Rangehood?
• Dishwasher?
• Microwave?
• Installation?
• Delivery?

If your expected appliance package is closer to $12,000, you already know the $5,000 allowance is unlikely to reflect your actual plans.

Identifying that before signing the contract gives you the opportunity to clarify the price rather than discovering the difference later.

Questions to Ask About Every Prime Cost Item

Before signing your building contract, go through the PC schedule line by line.

For each item, ask:

1. What exactly does this allowance cover?

Don't accept vague descriptions if they can reasonably be made more specific.

"Bathroom fixtures" is far less useful than identifying the individual fixtures being allowed for.

2. Is the allowance realistic for the products I want?

If possible, make your selections before signing.

If you already know you want a particular tile, tap, oven or bath, ask whether the exact product can be specified in the contract rather than relying on an allowance.

3. Does the allowance include supply only?

Understand what is and isn't included.

The treatment of installation, delivery, builder's margins, GST and other associated costs will depend on the wording of your contract.

4. What happens if I spend more than the allowance?

Ask the builder to explain exactly how any difference is calculated.

5. What happens if I spend less?

The contract should also make clear how savings against an allowance are treated.

6. Is there a builder's margin?

Check your contract rather than assuming the difference between the allowance and actual price is the only additional amount you could pay.

Queensland's standard PC and provisional sum schedule specifically provides for the builder's estimate, quantities or unit costs and contractor markup, demonstrating why homeowners should examine more than just the headline allowance.

Questions to Ask About Every Provisional Sum

Provisional sums deserve just as much scrutiny.

Ask:

1. Why can't this cost be fixed now?

There may be a perfectly legitimate reason.

But you should understand what information is missing and why a fixed price can't currently be provided.

2. What assumptions were used?

If $20,000 has been allowed for excavation, what is that figure based on?

Ask about:

• Soil reports
• Site surveys
• Engineering information
• Access
• Slope
• Excavation quantities
• Material disposal
• Equipment requirements
• Known site conditions

3. Has the builder made reasonable enquiries?

A provisional sum shouldn't simply replace investigation that could reasonably have been carried out before signing.

4. What happens if the actual cost is higher?

Understand exactly how the contract deals with the difference.

5. What happens if it is lower?

Again, check the contract.

6. Can the uncertainty be removed before signing?

Sometimes spending a little more time investigating a cost before signing can eliminate or reduce the provisional sum entirely.

Pay Particular Attention to Site Costs

Site costs deserve special attention because they're one of the areas where uncertainty can become expensive.

Excavation is a common example.

Imagine your contract contains:

Once excavation begins, significantly more material needs to be removed than anticipated.

Rock is encountered.

Extra machinery is required.

More truck movements and disposal are required.

The actual cost ends up considerably higher than the allowance.

That doesn't necessarily mean anybody has done something wrong — genuine unknowns can exist.

But it demonstrates why homeowners should understand the assumptions behind significant provisional sums before committing to a contract.

Consumer Affairs Victoria specifically uses excavation as an example of a provisional sum and recommends obtaining comprehensive site information, such as soil information, to improve the reliability of the estimate.

The More You Select Before Signing, the More Certainty You Can Create

One of the best ways to reduce PC-item uncertainty is simple:

Make more selections before you sign the building contract.

Where practical, decide on:

• Tiles
• Flooring
• Tapware
• Toilets
• Basins
• Baths
• Appliances
• Cabinet finishes
• Door hardware
• Electrical fixtures

Instead of:

you may be able to have something closer to:

The second option gives you significantly more clarity.

Consumer Affairs Victoria similarly recommends specifying selections such as make, model, colour and style where possible so the cost is more certain.

A Cheap Building Quote Isn't Always a Cheap Build

This is one of the most important lessons when comparing builders.

Don't compare contract totals in isolation.

Compare:

• What's included
• What's excluded
• PC allowances
• Provisional sums
• Material specifications
• Site-cost assumptions
• Builder margins
• Selection allowances
• Contract conditions

A $590,000 quote with unrealistic allowances may ultimately cost more than a $620,000 quote that has been priced more comprehensively.

The number at the bottom of the page doesn't tell the entire story.

For a broader look at the items that can push a building quote beyond its headline price, see the guide to hidden costs in a building quote.

Red Flags to Look For Before Signing

A building contract deserves further investigation if you notice:

• Large numbers of PC items
• Large numbers of provisional sums
• Very low allowances compared with your expected selections
• Vague descriptions
• Significant site works sitting under provisional sums
• Allowances that are difficult to compare between builders
• Important selections still undecided
• No clear explanation of how differences will be calculated
• Large gaps between the quality of the display home and the allowances in your contract

None of these automatically means the builder is doing something wrong.

They simply tell you where you should be asking more questions.

A Practical Pre-Contract Exercise

Before signing, create a simple list with four columns:

Go through every PC item and provisional sum in your contract.

This exercise can quickly expose where your apparent contract price and your realistic expected build cost may be heading in different directions.

10 Questions to Ask Before Signing

Before you sign your building contract, ask your builder:

1. Can you give me a complete schedule of all Prime Cost Items and Provisional Sums?
2. Which allowances are most likely to change?
3. How were these allowances calculated?
4. Are the PC allowances realistic for the level of finish I've requested?
5. Can I make more selections now and replace allowances with specified products?
6. Can any provisional sums be converted into fixed prices before signing?
7. What reports or investigations support the provisional sums?
8. How are increases or decreases against each allowance calculated under the contract?
9. What margins, GST, delivery or other charges could apply?
10. Can you show me what my likely contract price would look like using my expected selections rather than the minimum allowances?

If you can't clearly answer those questions, there may still be work to do before you're ready to sign.

Frequently Asked Questions

Are Prime Cost Items included in the contract price?

A PC allowance is generally included within the stated contract price, but it is an allowance rather than necessarily the final cost of the selected item. If the actual selection differs from the allowance, the final amount payable may change according to the contract.

Are Provisional Sums included in the contract price?

The allowance is generally incorporated into the contract price, but because it is an estimate for work whose exact cost isn't yet known, the final amount can vary.

Can a Prime Cost Item increase my building cost?

Yes. If your final selection costs more than the allowance, the amount payable can increase in accordance with your contract.

Can a Provisional Sum increase?

Yes. If the actual cost of the work covered by the provisional sum exceeds the amount allowed, the final amount can increase in accordance with the contract.

Should I avoid all PC items and provisional sums?

Not necessarily. Some uncertainty can be legitimate, particularly where selections haven't been made or the final scope of particular work can't yet be determined.

The objective is to reduce unnecessary allowances and make the remaining ones realistic and transparent.

Should I have my building contract reviewed before signing?

If you're unsure about allowances, contract clauses or significant financial exposure, consider obtaining independent professional advice before signing. Building contract requirements and consumer protections can also differ between Australian states and territories.

The Bottom Line

Prime Cost Items and Provisional Sums aren't just building-industry terminology.

They can directly affect how much your home ultimately costs.

Before signing a building contract:

The earlier you identify uncertainty, the more opportunity you have to investigate it, make selections and get clarity before construction begins.

A little extra work before signing a building contract can be far easier than trying to solve a budget problem halfway through the build.

Your Builder Co-Pilot is independent of building companies. We do not recommend builders or receive builder referral fees or commissions.

General information only. Building contracts and applicable laws differ between states and territories and between individual contracts. Consider obtaining independent legal, building or other professional advice appropriate to your circumstances.

Last reviewed: 19 August 2026