In construction, net margins are thin, so small costs that slip through unnoticed take a surprisingly large share of the profit. A bit of labour over budget on one job, a variation that never gets billed, materials charged to the wrong project - none of them look serious on their own, but together they can eat a big slice of what you take home. The fix isn't a bigger office team; it's seeing those costs while the job is still running, not weeks later in the monthly accounts.
Why thin margins make small leaks so expensive
The maths is simple, and it's worth doing with your own numbers. For example, if your business runs at a net margin of 5 per cent, and 2 per cent of revenue leaks away through costs nobody caught, you've lost about two-fifths of your profit - close to half. On a margin that thin, there's very little room for error.
Turnover can hide this. A busy year with plenty of work coming through can still end with a disappointing bottom line, because the leaks scale with the work. More jobs means more chances for small costs to slip.
Try it with your own figures:
- Take last year's net profit as a share of revenue.
- Estimate what share of revenue went on costs that weren't planned, billed or allocated correctly.
- Compare the two.
Even a rough estimate usually makes the case for better visibility.
Where the leaks usually happen
In our experience working with builders' systems, the same few areas come up again and again.
Labour creeping over budget
Hours are booked to a job, but nobody compares them with the estimate until the job is finished. By then, the overrun is locked in. If timesheets aren't coded to jobs and cost codes on the day, you can't see the drift as it happens.
Unbilled variations
The client asks for a change on site, the work gets done, and the paperwork never catches up. Without a variation register that tracks every change from request to invoice, some of that work is simply given away.
Costs on the wrong job
A supplier invoice gets coded to the wrong project, or to overheads. One job looks better than it is, another looks worse, and your estimating for the next job is based on bad data.
Committed costs you can't see
If you only see costs when the supplier invoice arrives, you're always looking backwards. Purchase orders and subcontract values tell you what's coming, so you can act before the money is spent.
Late claims
Progress claims that go out late, or under-claim the work done, put pressure on cash flow even when the job itself is profitable.
The fix: see costs while the job is running
The common thread is timing. Most of these leaks are caught eventually - in the monthly accounts, at job close or at year end. By then the money is gone. The goal is to see the same information weekly, or better, while there's still time to act.
That usually means:
- Job costing set up properly in your accounting or job management system, with budgets and cost codes for every job. Our construction job costing page explains the setup.
- Timesheets coded to jobs on site and flowing into both payroll and job costing without re-entry.
- Committed cost tracking so POs and subcontracts show up against the job budget before the invoice does.
- A variation register reviewed in every project meeting.
- Regular WIP reporting that shows over- and under-claimed positions on every job. See construction WIP reporting.
- A weekly cash flow view covering claims, commitments and payroll. Our construction cash flow forecasting page covers how to set one up.
Connect what you already have
Most builders don't need new software to fix this. They need the systems they already have - accounting, project management, timesheets, purchasing - to share data, so the numbers are current and nobody re-keys them. When the data flows automatically, a job cost report can be up to date every morning instead of once a month.
We explain the overall approach on our construction financial visibility page.
Frequently asked questions
What is a typical profit margin for an Australian builder?
It varies a lot by sector, project size and the type of contract, so compare against your own history rather than an industry average. What's true across the board is that margins are thin enough that small leaks matter.
How do I find out where my business is losing money?
Start by comparing estimated and actual costs on your last few completed jobs, line by line. Look for patterns: labour overruns, unbilled variations, or costs that landed on the wrong job.
Do I need new software to get real-time job costing?
Usually not. Xero and MYOB can handle job tracking, and many project management tools hold the rest. The gap is normally that the systems aren't connected, so the data is late or incomplete.
How often should a builder review job costs?
Weekly for active jobs is a sensible minimum. Monthly is too slow to catch overruns before they're locked in.
If you want to see your job costs while there's still time to do something about them, book a free initial chat. For a written review of where your systems are leaking, our $5,000 Process & Systems Audit is a good starting point.