Provisional sums, PC items and allowances explained
The three estimate lines where a quote can quietly move after you sign. What provisional sums, prime cost items and allowances really mean, and how to keep them tight.
Two quotes for the same job can look miles apart, and the reason is often hidden in three little terms: provisional sums, prime cost items and allowances. These are the parts of a contract that are estimated rather than fixed, so they are where the final figure can quietly shift once the real choices and conditions land. They turn up on new builds and renovations alike in SA and Victoria. Understanding them is the difference between comparing quotes properly and getting a surprise halfway through the job.
What each term actually means
A prime cost item, or PC item, is a placeholder for a product you have not chosen yet, like tapware, tiles, a cooktop or door handles. The contract carries an estimated figure, and when you make your final selection the difference is added or credited. A provisional sum covers work that cannot be priced exactly yet, often site works, excavation or anything depending on conditions that are still unknown. An allowance is the broader term for any estimated line the builder has put a number against pending the real detail.
Why they make quotes hard to compare
Here is the catch. One builder might allow a realistic figure for your tiles and site works, while another drops in a lower placeholder to make the headline price look sharper. On paper the second quote wins, but once you choose real tiles and the site is actually dug, the numbers converge, or the cheaper one overtakes. You are not really comparing the quotes until you compare the allowances behind them, line by line.
The two biggest culprits
Site works and finishes are where these items bite hardest. Site works, excavation and anything below the ground are a classic provisional sum, because until the soil report and the dig are done nobody knows exactly what is there. That is why finalising your soil testing and engineering before you sign matters so much, it turns a guess into a fixed figure. Finishes like tapware, tiles and appliances are the classic PC items, and lowballed selections are a common way a quote looks cheaper than it is.
How to keep them tight
You have more control than it feels. Ask the builder to list every provisional sum, PC item and allowance and explain each one. Push to make your selections early so PC items become fixed prices rather than open questions. Get the site conditions tested before signing so provisional sums for excavation shrink or disappear. And when you compare builders, line the allowances up against each other rather than trusting the bottom line, because that is where the honest comparison lives.
How to keep estimated items under control
- Ask for realistic allowances, not lowball placeholders
- Pin down selections early so provisional items become fixed
- Get soil and site conditions tested before signing
- Compare quotes on the same allowances, not just the headline price
- Ask for each estimated item to be listed and explained
- A quote padded with vague allowances to look cheaper
- Unrealistically low prime cost items for tapware, tiles or appliances
- Open-ended provisional sums for site works and excavation
- No clarity on what happens when the real cost differs
Provisional sums, PC items and allowances are simply the estimated parts of a contract, and they are where a quote can move after you sign. The fix is not to fear them but to tighten them: get realistic figures, make selections early, test the site before signing, and compare quotes on the allowances rather than the headline. Do that and the final figure holds far fewer surprises.
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What is the difference between a provisional sum and a PC item?
A prime cost item is a placeholder for a product you have not chosen yet, like tapware or tiles, where the difference is adjusted once you select. A provisional sum covers work that cannot be priced exactly yet, often site works or excavation that depend on conditions still unknown.
Why do two building quotes look so different?
Often because of the allowances hidden inside them. One builder may use realistic figures for finishes and site works while another drops in low placeholders to look cheaper. You are not really comparing quotes until you compare the allowances behind them, line by line.
How do I stop provisional sums blowing out?
Make your selections early so prime cost items become fixed, and get your soil and site conditions tested before you sign so provisional sums for excavation are based on fact, not guesswork. Ask the builder to list and explain every estimated item.
Are provisional sums a bad sign in a contract?
Not on their own, some work genuinely cannot be priced exactly up front. What matters is that the figures are realistic, each item is listed and explained, and you understand what happens when the real cost differs. Vague, lowballed allowances are the warning sign, not their existence.