Why 80% of Construction Projects Go Over Budget

Key takeaway

According to KPMG's Global Construction Survey, only 25 percent of construction projects come within 10 percent of their original budget. The average cost overrun sits between 28 and 33 percent, according to McKinsey Global Institute research. These are not outlier numbers from troubled projects. This is the industry baseline. The causes are well understood but rarely addressed systematically: uncontrolled procurement spending, late detection of budget deviations, scope changes without cost tracking, and poor visibility into real-time project costs. Construction companies that implement structured cost controls and procurement processes consistently outperform those that manage by intuition and spreadsheets.

The scale of the problem

The European construction market reached 3.72 trillion USD in 2025, according to IMARC Group. If the average project overruns by 28 percent, the total waste across the EU construction industry runs into hundreds of billions of euros annually.

For a mid-size contractor running five projects a year at 2 million euros each, a 28 percent overrun on total costs means 2.8 million euros in unexpected spending. At a net margin of 3 to 5 percent, that wipes out the profit from two entire projects.

This is not a theoretical problem. It is the primary reason construction companies fail.

The five causes that actually matter

Procurement without systematic comparison

Materials typically account for 40 to 60 percent of construction project costs. Yet most companies compare only 3 to 4 supplier quotes per purchase because there is no time for more.

The math is straightforward. If comparing 8 to 10 suppliers saves 5 to 10 percent on materials (which data consistently shows), and materials are 50 percent of your project cost, then you are losing 2.5 to 5 percent of total project value on every build.

On a 2 million euro project, that is 50,000 to 100,000 euros left on the table. Not because of bad negotiation, but because of insufficient comparison.

The fix is not hiring more procurement staff. It is automating the comparison process so that contacting 10 suppliers takes the same time as contacting 1.

Late detection of budget deviations

Most construction companies reconcile costs weekly or monthly. Some only do it at project completion. By the time a 10 percent overrun is detected, weeks or months of spending at the wrong rate have already happened.

The problem is not the accounting. It is the delay between spending and visibility. If your project manager does not know until week 8 that the concrete sub is 15 percent over budget, seven weeks of overcharging have already occurred.

Real-time budget tracking, where every purchase order and invoice is matched against the budget as it happens, catches deviations when they are small enough to fix.

Change orders without cost impact analysis

Scope changes are inevitable in construction. The problem is not that changes happen. It is that changes happen without anyone calculating the cost impact until after the work is done.

A design change that adds 50 square meters of glazing seems simple on a revised drawing. But that change affects structural steel, facade framing, sealant, interior finishing, and possibly HVAC capacity. Without tracing the cost impact across all affected categories, the true cost of the change is invisible until final reconciliation.

Material price volatility without hedging

Construction material prices in the EU rose 25 to 40 percent between 2021 and 2024. Even in 2026, prices for concrete, steel, and insulation fluctuate month to month.

Projects budgeted at today's prices and delivered over 12 to 18 months face significant price risk. Without tracking material price trends and timing large purchases strategically, companies absorb price increases that erode margins.

Spreadsheet errors

This is the least discussed but possibly most common cause. Research by Professor Raymond Panko, validated by KPMG and PwC audits, shows that 88 to 90 percent of spreadsheets contain errors.

In construction procurement, a misplaced decimal point in a cost comparison can mean choosing the wrong supplier. A formula error in a budget tracker can hide a 50,000 euro overrun for months. A copy-paste mistake in a material order can result in the wrong quantity being delivered.

These are not dramatic failures. They are quiet, cumulative errors that add up to significant money over the life of a project.

What companies that stay on budget do differently

Companies that consistently deliver projects within budget share several practices:

They compare more suppliers on every purchase. Not 3. At least 8. They use standardized request processes or automation to make this feasible.

They track spending in real time, not monthly. Every purchase order is matched against the budget within days, not weeks. Deviations are flagged at 5 percent, not discovered at 25 percent.

They calculate the cost of every change order before approving it. The answer to "can we add this?" always includes "and it will cost this much, affecting these budget lines."

They use structured data, not spreadsheets, for critical calculations. Purpose-built tools eliminate the formula errors, copy-paste mistakes, and version conflicts that plague Excel-based budget management.

They negotiate from data, not habit. When you have 6 months of supplier pricing data, you know whether this month's quote is fair. When you are calling the same 3 suppliers every time, you have no benchmark.

FAQ

What is the average construction cost overrun percentage?

The average construction project cost overrun is 28 to 33 percent above the original budget, according to McKinsey Global Institute research analyzing thousands of projects globally. KPMG found that only 25 percent of projects finish within 10 percent of their budget. These figures are consistent across residential, commercial, and infrastructure projects.

Are cost overruns worse in the EU than elsewhere?

Cost overrun rates are broadly similar across developed markets. The EU, US, and UK show comparable percentages. However, EU projects face additional complexity from cross-border material sourcing, varying national building codes, and recent material price volatility driven by energy cost increases.

What percentage of project costs goes to materials?

Materials typically represent 40 to 60 percent of total construction project costs, depending on project type. Residential projects tend to be at the lower end (40 to 50 percent). Infrastructure and commercial projects can reach 55 to 60 percent. This makes material procurement the single largest controllable cost category.

Can technology alone solve construction cost overruns?

No. Technology addresses specific causes (procurement comparison, real-time tracking, data accuracy) but cannot fix organizational issues like poor change order management or unrealistic initial estimates. The most effective approach combines better tools with better processes and management discipline.

How quickly can a company improve its budget performance?

Companies that implement structured procurement and real-time budget tracking typically see measurable improvement within 2 to 3 projects. The first project establishes a baseline. The second project applies lessons learned. By the third project, the process is embedded and results are consistent. Full impact usually appears within 6 to 12 months.