Construction cost control: where the money leaks and how to close off rework, purchasing and change orders
Construction cost control starts with recording every invoice and every payment against the right project and stage. Then compare actual with budget every week. Money leaks through three doors: rework, which costs 2% to 9% of the project, last-minute purchases and extra work without a signed change order.
Why does the project cost go over budget?
Because the budget is made once, and the cost happens every day, in small decisions on the jobsite. If nobody links the day's decision to the project's number, the difference only shows up at the end.
Last year made the math tighter. According to FGV IBRE, the INCC-M ended 2025 up 6.10%. Labor rose 9.23%, more than double materials and equipment, which rose 3.75%.
| INCC-M, 2025 | Increase for the year |
|---|---|
| Overall index | 6.10% |
| Labor | 9.23% |
| Materials, equipment and services | 3.92% |
| Materials and equipment | 3.75% |
With labor more expensive, idle hours and redone hours weigh more. A day with a work front stopped waiting for material costs the whole crew. Redone work pays for labor twice.
How much does rework cost on the project?
According to Lucio et al. (2016), cited in a UTFPR paper, rework costs 2% to 9% of a project's total value. It is one of the largest losses a construction company controls.
The table uses example project values:
| Project value (example) | 2% rework | 9% rework |
|---|---|---|
| R$ 300K (renovation) | R$ 6K | R$ 27K |
| R$ 800K (house) | R$ 16K | R$ 72K |
| R$ 3M (small building) | R$ 60K | R$ 270K |
Rework almost always starts with information that didn't arrive in time:
- The message got lost. The foreman said in the group chat that the measurement didn't match, and the work front kept going.
- The change wasn't recorded. The client asked for a different outlet position during a visit, and the electrician never knew.
- The pending item had no owner. Everyone saw the leak in the photo, and nobody followed up.
- The check came too late. The error was found after the plaster, not before.
None of these cases calls for expensive technology. It calls for every warning to become a pending item with an owner, a deadline and a photo. And for someone to follow up until it closes.
How do last-minute purchases make the project more expensive?
Last-minute purchases cost more in price and in time. With no time to get quotes, the construction company pays the nearest supplier's price. And the work front sits idle until the material arrives.
The usual path is this: the foreman notices the shortage and calls the office. Someone buys by phone, and the invoice arrives by email days later. When the invoice arrives, nobody remembers which project it belongs to.
To close that door:
- The shortage becomes a request the same day. With quantity, project, work front and date needed.
- The request has an approval. Whoever approves sees the stage's balance before releasing it.
- The invoice goes to the right project. The supplier's NF-e is recorded with project, stage and item.
- The delivery is checked. The foreman checks the quantity, and the jobsite inventory adds it up.
- The inventory warns in advance. A minimum balance per material makes the purchase go out before the shortage.
With the invoice in the right project, each stage's actual stays up to date. That is the number the engineer compares with the budget.
Is extra renovation work without a change order a loss?
Often, yes. The client asks for a change during a visit, the crew does it, and the amount only appears on the final bill. If there is no written approval, the dispute begins.
The law favors the record. Under art. 619 of the Civil Code, a contractor who follows the agreed plan cannot demand a price increase for project changes. The exception is a change that results from the owner's written instructions.
The sole paragraph opens a second, harder door. The owner pays the increase if, always present at the work, they could not have ignored the change and never objected. In practice, this becomes a dispute over proof.
The problem is common in renovations. The 2025 UFU case study by Siqueira records a high incidence of rework and of work outside the original scope in renovation projects. That work requires change orders and affects budget and schedule.
This is an example change order for a flooring change request:
| Change order item (example) | Amount |
|---|---|
| Porcelain tile instead of ceramic, 42 m² | R$ 4,200 |
| Extra mortar and grout | R$ 680 |
| Additional labor | R$ 1,500 |
| Change order total | R$ 6,380 |
| Additional time | 3 days |
The rule that protects the construction company fits in three steps: log the request the same day, approve it in writing before doing the work and keep the acceptance with name, date and time. The amount goes on the next bill, along with the rest of the project.
How do you track cost per project every week?
Every week, compare the budget and the actual for each stage. The actual comes from the invoice and the bank statement, not from memory. The difference becomes a pending item with an owner.
This is an example weekly table for a project:
| Stage (example) | Budget | Actual | Variance | What to do |
|---|---|---|---|---|
| Foundation | R$ 62,000 | R$ 64,100 | +3.4% | Closed; record the cause |
| Masonry | R$ 48,000 | R$ 39,500 | In progress | Check the block balance |
| MEP | R$ 35,000 | R$ 41,200 | +17.7% | Pending item for the engineer: plumbing rework |
| Finishes | R$ 90,000 | R$ 12,300 | Starting | Porcelain tile change order approved |
Four habits keep the table reliable:
- Every invoice has a project and a stage. An invoice without a project is the most common gap in cost control.
- Every payment has an invoice. A payment without an invoice becomes a pending item the same day.
- Every variance has an owner. A variance above the agreed limit goes to the engineer with a deadline.
- Every extra has a change order. Without an approved change order, the work doesn't start.
To record what happens on the jobsite day by day, see what to record in the construction daily log. To choose the tool, see what to check in construction management software.
How CERNE solves it
CERNE brings together purchasing, jobsite inventory, pending items and finance for each project in the same system.
- Purchasing from the invoice. The supplier's NF-e comes in with project, item and amount, with no typing.
- Requests with approval. A material shortage becomes a request, with quantity and project. The person in charge approves, and the checked delivery adds to the inventory.
- Finance per project. Each project's payables and receivables, with the bank statement reconciled.
- Pending items with an owner. The foreman's message on WhatsApp becomes a pending item with owner, deadline, photo, project and work front. If it isn't cleared on time, CERNE reminds the owner and alerts the engineer.
- Change order approved by link. The client's request becomes a change order with materials and labor added up. The client approves through the link, with name and time.
- Direct questions. In the AI assistant, the engineer asks "what has been stuck for 3 days in tower B?".
Those who already use Sienge, UAU or Mega keep the budget and accounting there. CERNE integrates through the API and handles the jobsite on top. The construction package starts with an assessment of your project. It uses modules already running at CERNE clients: the board with owner and deadline, and approval before any order. See the workflows on the construction and engineering page and the cards for each role.
Start with an assessment
The tables in this article use example numbers. Your project's tables use your invoices and your budget. Start with an assessment of your operation: our team finds where each project's cost leaks and builds the controls with you. Book the assessment.
Frequently asked questions
- How do you control the costs of a construction project?
- Record every invoice and every payment against the right project and stage, compare actual with budget every week and treat variances as pending items with an owner. What leaks most is rework, last-minute purchases and extra work without a change order.
- How much does rework cost on a construction project?
- According to Lucio et al. (2016), cited in a UTFPR paper, rework costs 2% to 9% of a project's total value. On an R$ 800K project, that ranges from R$ 16K to R$ 72K.
- How much did construction costs rise in 2025?
- FGV's INCC-M rose 6.10% in 2025. Labor rose 9.23%, and materials and equipment rose 3.75%, according to the FGV IBRE press release of December 23, 2025.
- Is the client required to pay for extra work on a renovation?
- Under art. 619 of the Civil Code, a contractor who follows the agreed plan cannot demand an increase for project changes, unless the owner gave written instructions. Without them, billing depends on proving the owner followed the work and never objected.
- How do you write a change order for a renovation contract?
- Log the client's request, describe the work, add up materials and labor, state the new deadline and get written approval before doing the work. Keep the acceptance with name, date and time.
- What is the difference between budgeted cost and actual cost?
- Budgeted is what the project should cost at each stage. Actual is what was paid, according to the invoice and the bank statement. The difference, stage by stage, shows where to act while there is still time.
Sources
- FGV IBRE, INCC-M for December 2025, press release of December 23, 2025, via SindusCon-SP
- UTFPR, paper citing Lucio et al. (2016) on the cost of rework
- UFU, Siqueira, case study on contract amendments in a renovation project, 2025
- Civil Code, Lei 10.406/2002, arts. 618 and 619 (construction contracts)