A construction project forecast should answer a relatively simple question: Based on everything we know today, where do we genuinely expect this project to finish? Getting to that answer is rarely simple. Construction projects change constantly. Productivity varies. Programs move. Procurement outcomes differ from tender assumptions. Variations emerge. Subcontractor positions develop. Risks become clearer as work progresses. A reliable project forecast needs to bring all of that information together. It shouldn't simply reproduce the original budget with actual costs inserted. The forecast needs to become the current financial view of the project.
Start with the current contract position The starting point is understanding what the contractor is actually entitled to be paid. Management should distinguish between:
- original contract value
- approved variations
- submitted but unapproved variations
- identified variations not yet submitted
- claims
- other potential commercial recoveries.
These shouldn't automatically be treated as though they have the same certainty. An approved $500,000 variation is fundamentally different from a $500,000 claim that hasn't yet been assessed by the customer.
Make sure cost to date is complete The accounting system provides an important starting point for project costs. But simply extracting costs from the general ledger isn't necessarily enough. Subcontractors may have performed work that hasn't yet been invoiced. Materials may have been delivered without an invoice being processed. Site teams may know about commitments finance hasn't yet seen.
Management therefore needs confidence that cost to date represents the economic reality of the project, not simply invoices processed by month-end.
Cost to complete is where the real forecasting happens Historical costs tell management what has happened. Cost to complete determines where the project is going. For each major cost category, the project team should estimate what is genuinely required to finish the work. That can include:
- remaining labour hours and productivity
- plant and equipment
- materials
- subcontract packages
- site supervision
- temporary works
- project overhead
- testing and commissioning
- demobilisation
- defects and close-out
- expected completion timing.
The question isn't: "What budget do we have left?" It is: "What will it actually cost from today to finish this project?"
Reforecast productivity rather than carrying the tender assumption If the tender assumed a particular production rate but actual performance has consistently been lower, simply carrying the original productivity assumption through the remaining forecast can create an unrealistic result. Management should ask: What productivity have we actually achieved? Why has it differed from estimate? What will genuinely change going forward? Improvement should have an operational basis.
Update the program and completion date Time costs money.
If a project was originally expected to finish in June but is now realistically going to finish in September, the financial forecast needs to move with the program. Additional time can create:
- site supervision costs
- project management costs
- plant hire
- temporary facilities
- accommodation
- traffic management
- security
- insurance
- other site overhead.
The operational program and financial forecast should tell the same story.
Forecast subcontractors by package Large subcontract packages deserve individual attention. Management should understand: Original package budget Current commitment Approved subcontract variations Expected future variations Claims or disputes Remaining work Forecast final subcontract cost The purchase order or subcontract value is not necessarily the final cost.
Treat variations according to their certainty A useful approach is to separate variations into categories such as: Approved Submitted Identified but not submitted Disputed Management can then decide what level of recovery is appropriate to include in the base forecast. The important thing is that assumptions are explicit.
Separate the base forecast from risks and opportunities A project will almost always have things that could improve or worsen the final result. Rather than quietly incorporating every possible positive outcome into the base forecast, it can be useful to show: Base forecast Key risks Key opportunities This allows management to understand both the most realistic current outcome and the range around it. A forecast should represent the expected outcome. It shouldn't require everything to go right.
Reconcile movement from the previous forecast One of the most useful parts of a project forecast is understanding what changed. For example: Previous forecast profit: $1.20m Labour productivity: ($150k) Program extension: ($100k) Procurement saving: +$75k Reduced variation recovery: ($125k) Current forecast profit: $0.90m That bridge tells management far more than the final margin alone.
Connect the project forecast to cash Profitability and cash should not be forecast independently. Management should understand:
- expected progress claims
- billing timing
- variation recovery
- debtor collection
- retentions
- major supplier payments
- subcontractor payments
- peak project cash exposure.
A project generating $2 million of forecast profit but requiring $4 million of peak working capital presents a different proposition from one generating the same profit with minimal funding requirement.
Assign actions to the forecast Forecasting shouldn't finish when the spreadsheet is updated. If the review identifies an issue, there should be an action. For example: Variation outstanding then Commercial Manager to resolve with client. Labour productivity below forecast then Project Manager to review crew structure and methodology. Program extension creating additional overhead then Project team to quantify extension-of-time entitlement. Cash collection delayed then Finance and Project Manager to escalate certification. Actions should have owners and dates.
Forecast monthly For material projects, monthly forecasting creates a useful discipline. Each month, the project team should reassess: Contract value Cost to date Cost to complete Completion date Variations Subcontract exposure Risks and opportunities Cash position Forecast final margin
What should management see? A useful project summary should make the important information obvious: Original contract value
Current forecast revenue Original margin Current forecast margin Movement since previous forecast Cost to complete Approved and unapproved variations WIP Debtors and retentions Project cash exposure Key risks and opportunities Actions and owners
Warning signs that a forecast needs more challenge I would look more closely when:
- forecast margins rarely move despite significant project activity
- cost to complete closely mirrors remaining budget
- completion dates move without associated cost increases
- unresolved variations represent a large proportion of forecast profit
- subcontract commitments are treated as forecast final cost without further assessment
- productivity assumptions improve significantly without a clear operational reason
- known risks sit outside the forecast indefinitely
- forecast changes aren't reconciled to the previous month
- project cash exposure isn't understood
- project teams can't clearly explain the assumptions behind the forecast.
A detailed forecast isn't necessarily a reliable forecast. Reliability comes from the quality of the assumptions underneath it.
The forecast should represent today's best view A project forecast will never predict the final outcome perfectly. That isn't the standard. The standard should be: Given everything we know today, is this our most realistic view of where the project will finish? If new information emerges next month, the forecast should change. That is exactly what a forecast is supposed to do. A reliable forecast gives management visibility while there is still time to act.
And it creates a disciplined conversation around one of the most important questions in any construction business: Where are our projects really going to finish?
Salt Strategic Advisory works with growing construction, infrastructure and project-based businesses to strengthen project forecasting, financial visibility, cash flow and commercial decision-making. If project forecasts are difficult to trust, the starting point is often not a more complicated spreadsheet. It is strengthening the assumptions, ownership and review process behind the numbers.