How Contractors Can Reduce Cost Overruns on Construction Projects

Eighty-five percent of construction projects worldwide exceed their original budgets, according to research published in the International Journal of Innovation, Management and Technology. The average overrun across a 70-year, 20-country dataset lands at 28%, based on findings reported by the McKinsey Global Institute. For mega-projects above $100 million, that average climbs to 45%.

This is no mere series of individual failures; they are the result of the way the industry is structured, since it works with very narrow profit margins, is subject to fluctuations in the cost of materials, suffers from poor and fragmented communication, and has to meet tight deadlines. The Construction Financial Management Association states that the average net profit margin for construction companies in the United States is 6.2 percent; with such a margin, a project worth $5 million yields a profit of $310,000. However, a 10 percent overrun eliminates that profit and a 15 percent overrun results in a loss.

It is not the contractors who completely avoid surprises who manage to remain profitable. Rather, they are those who establish systems covering the six areas in which overruns actually occur: estimating, scope management, procurement, labor planning, change order control, and project tracking.

Where Cost Overruns Actually Start

The Construction Industry Institute found that 32 percent of all cost overruns were directly due to estimating errors. According to data from KPMG, 69 percent of projects have overruns that go beyond 10 percent of the original budget. Research carried out by the PMI shows that inadequate communication is the cause of one-third of construction project failures. Meanwhile, Procore Technologies states that 52 percent of projects suffer scope creep after construction has started.

Although these root causes overlap, they can be grouped into six categories that explain the majority of budget failures in both residential and commercial projects.

Each of these categories has its own set of warning signs and its own set of fixes. The contractors who address all six outperform the ones who focus on only one or two.

Estimating Errors: The Overrun That Starts Before the First Shovel

The bid is the first stage at which a project can go wrong, and estimating errors are still the biggest among the controllable causes of cost overruns. If a quantity takeoff omits 10% of the drywall area on a commercial interior job, it does not result in a 10% mistake; instead, it sets off a chain reaction. The omission of the drywall leads to omissions of taping, priming, painting, and the ceiling work above it, and one error in the takeoff builds upon itself among the various trades.

According to the 2026 industry benchmarks, manual takeoffs have a fatigue error rate ranging from 5% to 10% when applied to large drawing sets. Digital takeoff tools such as Planswift and Bluebeam manage to reach an accuracy level between 95% and 99% on standard plans. The accepted industry standard for the accuracy of a detailed bid-level takeoff is a variance from the actual quantities of 2% to 5%; if the variance exceeds this range, the margin begins to be eroded before construction starts.

How to Reduce Estimating-Driven Overruns

Localized Pricing: National averages hide regional price differences that can swing a line item by 15% to 30%. RSMeans publishes localized cost data for over 970 U.S. and Canadian locations. Pricing a project in Miami using data from Detroit produces a number that does not reflect the actual cost of labor, material, or equipment in that market.

Specification Cross-Check: A floor plan shows a wall. The specification tells you whether that wall gets standard latex paint or a three-coat high-performance system that costs five times more. Every quantity needs to be priced against the exact product the spec names, not a generic placeholder.

Trade-Level Separation: Lumping trades together hides the price drivers that determine whether a bid wins or loses. A line-item estimate organized by CSI MasterFormat division lets the contractor see where the cost sits and where adjustments are possible. A structured cost estimation process separates each trade into its own priced line so nothing gets buried inside a lump sum.

Accurate Quantity Measurement: On projects with multiple trades, tight deadlines, or incomplete drawings, the takeoff needs to be measured from the plans, not estimated from memory. Trades like waterproofing, roofing, and below-grade work are especially prone to quantity errors because the affected areas often span multiple drawing sheets. A detailed set of waterproofing estimating services measures every membrane, flashing, and sealant joint from the plans so that nothing below grade or behind the envelope gets missed in the bid. Every measured quantity should link to a specific spot on the drawing set so anyone reviewing the estimate can verify where the number came from.

Risk-Based Contingency: A flat 10% contingency applied to every project ignores the actual risk profile of the job. Projects with incomplete drawings, hazmat exposure, or phased occupancy carry higher risk and need higher contingency. Projects with clean documents and familiar building types need less.

Scope Creep: The Overrun Nobody Approves

Scope creep refers to the situation where the work on a project slowly extends beyond what was originally agreed upon in the contract without there being a change order to cover the extra cost. It is present in 52 percent of construction projects and is responsible for a major portion of the cost overruns that contractors have to absorb without being able to get the money back.

Change orders on commercial construction projects average 8% to 14% of total contract value, according to Navigant research republished by the AIA. On projects with weak scope documentation, that figure climbs past 25%. The average construction dispute in North America reached $60.1 million in 2024, a 40% increase from the prior year. The most common cause for six of the last nine years has been errors and omissions in contract documents, based on data from the Arcadis 2025 Global Construction Disputes Report.

How to Reduce Scope-Driven Overruns

Written Scope Boundaries: The phrase “as per plans and specs” appears on thousands of subcontract scope sheets, and it is the single most common scope anti-pattern in commercial construction. It transfers ambiguity to the field and creates disputes when two parties interpret the same drawing differently. Every trade scope should name what is included and what is excluded.

Pre-Work Authorization: Work performed without a signed change order is work the contractor may never get paid for. Written authorization for every scope addition, no matter how small, needs to be in place before a single hour of labor gets spent on it.

Pre-Bid Document Review: As many as 70% of projects experience rework due to design inconsistencies or errors. A pre-bid document review that flags coordination conflicts between architectural, structural, and MEP sheets catches problems when they cost the least to resolve. The 1-10-100 rule applies here. An error that costs $1 to fix on paper costs $10 during procurement and $100 once it is built.

Weekly Scope Tracking: Scope creep is invisible when nobody is comparing current field activity to the original contract scope. A weekly comparison catches drift early, when it can be documented and priced as a change order instead of absorbed as a loss.

A quantity takeoff that is detailed and assigns each measured item to a specific location establishes the paper trail which makes it possible to enforce the scope boundaries since each quantity can be traced back to a marked-up drawing, disagreements about what was included and what was not become much easier to settle.

Material Price Volatility: The Overrun the Market Delivers

The Bureau of Labor Statistics Producer Price Index shows that prices for construction materials went up by 6.2% in 2025, which is the biggest single-year rise since the spike caused by the pandemic in 2021. The situation in 2026 is even more varied. Steel and aluminum prices are expected to rise by 20% to 30% as a result of Section 232 tariffs, which in some cases have reached 50% for imported products. Following the rise in tariffs, aluminum prices have increased by about 40% in the United States. Copper prices are forecast to rise by 25% to 50% because of global demand. Lumber prices are projected to increase by 20% to 40% due to supply constraints. Concrete prices are also rising by 10% to 25% because of higher energy costs.

In the first two months of 2026, construction price inputs increased by 12.6% on an annualized basis, and since materials account for 40% to 60% of the total project cost, accurate material pricing is one of the most effective areas for preventing cost overruns.

How to Reduce Material-Driven Overruns

Category-Level Tracking: The tracking at the category level shows that steel, copper, lumber, and concrete follow different cycles since they are subject to different supply constraints and tariff exposures. The blended construction cost index eliminates the volatility that is actually relevant to the materials required by a particular project.

Escalation Clauses: Fixed-price contracts are especially vulnerable. A 20% material cost increase can wipe out 50% to 70% of the profit margin on a fixed-price job. Escalation clauses tied to third-party commodity indexes like the BLS Producer Price Index protect the contractor without creating open-ended risk for the owner.

Early Lock-In on Critical Materials: When cash flow allows, securing inventory at current prices on high-volatility materials like steel and specialty metals can produce significant savings. Storage costs of 1% to 3% per month are often far less than the 15% to 35% escalation those materials may experience over a six-month project timeline.

Multiple Vendor Relationships: Building relationships with three to five vendors for each critical material provides competitive pricing, faster delivery options of 3 to 5 days instead of 2 to 3 weeks, and a fallback when one supplier runs into stock or delivery issues.

Labor Shortages: The Overrun That Slows Everything Down

According to the Associated Builders and Contractors, the U.S. construction industry will have to recruit 349,000 net new workers in 2026 if it is to keep its labor levels stable. This number increases to 456,000 by 2027. Almost all of the demand in 2026 is due to retirees leaving the workforce rather than to an increase in new projects. The Associated General Contractors of America found that 42% of firms suffered project delays specifically because of labor shortages, making workforce gaps the most frequently mentioned cause of delay in its 2026 Workforce Survey.

The average hourly earnings of all construction workers were $40.97 in April 2026, as shown in data from the BLS. Wages increased by 3.1% on a year-on-year basis in the first quarter of 2026. The shortfalls are most pronounced in licensed and highly skilled trades, such as electricians, plumbers, HVAC technicians, welders, and heavy equipment operators.

If there is a shortage of labor, the projects will take longer; and if they take longer, then the cost of general conditions rises, the equipment remains idle, and overhead builds up more quickly than the budget is able to cover.

How to Reduce Labor-Driven Overruns

Realistic Crew Planning: A bid that assumes full crew availability during peak summer months in a tight labor market is a bid built on a wish, not a plan. Realistic crew sizes, overtime premiums, and potential schedule extensions need to be factored into the labor line before submission.

Weekly Labor Tracking: If the project is found to be 20% over its budget in terms of labor hours at the halfway stage, this fact must come to light in real time and not only appear in a monthly accounting report weeks after the cost overrun has already occurred

Prefabrication: Moving work off the jobsite and into a controlled shop environment reduces field labor hours, improves quality, and insulates the project from weather delays and site congestion that slow production.

Retention Over Recruitment: Replacing a skilled tradesperson costs significantly more than retaining one. Competitive pay, consistent hours, clear communication, and safe working conditions reduce the turnover that forces contractors to train new workers in the middle of active projects.

Change Order Management: The Overrun That Compounds

Change orders are a normal part of construction. Margin erosion from poorly managed change orders is not. Design changes contribute to 56.5% of cost overruns and 40% of project delays. Rework and delays cost the U.S. construction industry an estimated $177 billion annually, according to the FMI and PlanGrid Construction Disconnected report. Poor communication and poor project data account for 48% of that rework, representing $31.3 billion in annual losses.

According to the Construction Industry Institute, rework accounts for 5% to 9% of project costs, and design errors driving change orders are a major factor. Although change orders generally account for 10% to 25% of the total contract value, the hidden costs resulting from disruption, coordination overhead, and lost productivity frequently surpass the amount stated in the individual line items by 30% to 40%.

How to Reduce Change Order-Driven Overruns

Price Before You Perform: Any work carried out before a change order has been priced and approved is work for which the contractor will never be able to recover the full cost; data from the industry indicates that contractors who carry out the changed work first and then negotiate the price end up recovering less than those who price the change beforehand.

Real-Time Documentation: Digital tracking removes the usual 24-day average delay in processing change orders and ensures that reliable records are available when disputes occur. In 2024, the average amount of a construction dispute was $60.1 million, which represents a 40% increase compared to the previous year.

Preconstruction Conflict Review: Most error-driven change orders begin as an RFI. The RFI reveals a drawing gap; the gap requires altered work, and the altered work becomes a change order. Catching the gap before the RFI is written prevents the change order from forming in the first place.

Full Markup on Every Change: Industry standard is 10% to 15% combined overhead and profit on change orders. Many institutional contracts cap markup at 10%, and markups on subcontractor work are often capped at 5%. Leaving markup off change order pricing means the contractor absorbs the administrative and coordination cost of every change.

Each deliverable is structured in such a way that every trade is set out on its own line with its own unit cost; upon the arrival of a change order, the contractor is able to identify the scope that has been affected, reprice the individual line items, and then submit a documented adjustment rather than trying to guess the impact.

Project Cost Tracking: The System That Catches Everything Else

All of the strategies mentioned depend on one factor: visibility. Those contractors who keep a weekly record of their costs are able to detect problems while they still can be fixed. In contrast, those contractors who depend on monthly accounting reports will always be looking at data that is already several weeks old.

According to the AGC and Sage 2026 Construction Hiring and Business Outlook, 62% of companies currently list an economic slowdown or recession as their main concern, 57% name a lack of available workers as their primary issue, and 56% point to increasing labor costs as their key concern. Under such circumstances, real-time cost tracking is no longer a luxury; it is the system that turns every other overrun-reduction strategy into a working process.

Three Cost Tracking Habits That Prevent Overruns

Weekly Budget Comparison: A comparison of the weekly budget finds that a 30-minute review of costs each week picks up more issues than any monthly report does. By comparing the actual expenditure with the original estimate for each trade and for each phase, deviations can be detected before they turn into losses.

Change Order Percentage Monitoring: When the percentage of change orders is rising above 10% of the contract value, there should be immediate action taken with regard to either the scope documentation or the field management process.

Task-Level Labor Separation: Knowing that the total labor cost is 15% over budget is useful, but the fact that framing labor is on target while finishing labor is 30% over budget is actionable. Providing task-level tracking enables the project manager to identify where the problem lies, not just that a problem exists.

Cost Overrun Prevention by Project Phase

Overrun prevention is not a single action. It is a set of controls applied at every phase of the project, from preconstruction through closeout.

The Contractors Who Stay Profitable Build Systems, Not Hope

The Buildertrend State of Residential Construction Report shows that almost 25 percent of builders did not make a net profit in 2025. Of those companies that earned more than $6 million each year, the unprofitable ones had an average loss of $100,000. Twenty per cent of builders do not completely understand the difference between margin and markup, and 40 percent do not know how to calculate their work-in-progress-adjusted accrual figure.

The reason why some contractors are profitable while others are not is usually not a single disastrous error; rather, it is the result of a number of small mistakes accumulating over time in the areas of estimating, procurement, labor management, and field tracking.

It is clear from the data what works: accurate takeoffs lead to a reduction in estimating error, defined scope boundaries help to prevent scope creep, escalation clauses guard against major fluctuations, weekly cost tracking picks up on drift before it turns into a loss, and a formal change order management system turns scope changes from margin killers into documented, priced, and recoverable events.

Each estimate 247 prepares includes trade-level separation, ZIP-code pricing, and a marked-up plan set in which each quantity links to a specific position on the drawings. The degree of detail provided gives contractors a documented basis from which each subsequent cost control measure can be more effectively carried out. Upload your plans through the contact page to start with numbers you can build a system around.