Budget overruns rarely come from one big mistake. They build up: a design change here, an unpriced variation there, escalation nobody allowed for, a progress claim paid ahead of the work. A quantity surveyor’s job is to see those pressures early and keep the forecast final cost in front of the people making decisions.
This article combines our earlier guides on how QSs control costs and on how they protect clients from overruns.
Why projects go over budget
- An unrealistic starting budget, set before the design was understood.
- Scope creep and design changes during documentation and construction.
- Escalation in labour and material prices over a long programme.
- Latent conditions such as ground, services or existing structures.
- Poor variation control: work done before it is priced and approved.
- Over-certified progress claims that leave too little money for the remaining work.
Cost control: what a QS actually does
1. Sets a realistic budget
Early feasibility estimates and elemental cost plans test the brief against the budget before design money is spent.
2. Keeps the design on budget
The QS re-prices the design at each stage and offers value engineering options when it drifts over.
3. Gets the procurement right
Clear tender documents, a bill of quantities and like-for-like tender analysis reduce the gaps that turn into variations later.
4. Reports cost every month
A good cost report shows the contract sum, approved and pending variations, provisional sum adjustments, risks, contingency remaining and the forecast final cost against budget.
5. Controls variations
Every change is priced before it is approved, recorded in a register and reflected in the forecast.
6. Checks progress claims
Claims are assessed against the work done on site, so the client never pays ahead of progress. In WA, payment schedules must meet the timeframes in the Security of Payment Act 2021.
7. Agrees the final account
Closing variations as you go means the final account holds no surprises.
Risk management
- Risk register: list each risk, its likelihood and cost impact, who owns it and how it will be managed.
- Contract risk allocation: make sure the contract places each risk with the party best able to manage it.
- Contingency: size it from the risk register, not a guess, and track how it is drawn down. See what is a contingency sum?
- Escalation allowance: base it on the programme and current market indicators.
Cash flow forecasting
Owners and financiers need to know not just how much, but when. A QS-prepared cash flow forecast, updated monthly, helps line up funding drawdowns with progress claims. See our cost management and forecasting guide.
Example: catching an overrun early (illustrative)
Halfway through a Perth commercial fit-out, the monthly cost report shows pending variations for extra services coordination and upgraded finishes worth 6% of the contract sum, while 3% contingency remains. Because this shows up in month three rather than at practical completion, the client can choose to approve some items, defer others or fund the gap, before the money is spent.
Frequently asked questions
When should I bring in a QS to control costs?
As early as possible. The biggest savings are available before the design is fixed.
Can a QS help if my project is already over budget?
Yes. A QS can re-forecast the final cost, review pending variations and claims, and identify savings in the remaining work.
Do builders use quantity surveyors for cost control too?
Yes. Contractor-side QSs track actual costs against the tender budget, recover variations and protect the margin.
Want your project costs under control? Call Measure Manage on 0498 202 445 or see our quantity surveying services.