Why do maintenance budgets get so easily out of hand?

Owning a home or managing property in 2026 presents a constant challenge: controlling maintenance costs. Whether it's a private home owner who has a dormer installed or an association of owners (VvE) that plans major maintenance; the reality is that the final invoice rarely matches the initial budget. In an economic landscape characterised by the scarcity of professionals and fluctuating material prices, exceeding maintenance budgets has become the rule rather than the exception.

But what underlies these financial outliers? It is rarely a single factor, but rather a cumulation of hidden flaws, optimistic schedules and external market forces that shake even the most accurate budget.

The law of inhibiting advantage: Hidden flaws

The most common reason for budget overruns in 2026 is the discovery of unforeseen problems as soon as work begins. In construction, people often speak of the “Pandora's Box” that opens as soon as a wall is demolished or a roof is opened.

• Cumulative damage: When replacing a few rotten frames, the contractor often discovers that the leakage that caused the rot also affected the underlying supporting structure. What started as a cosmetic procedure worth a few thousand euros is turning into a structural renovation.
• Historic surprises: Especially in older cities such as Utrecht, Leiden or Dordrecht, builders often encounter archaeological remains or old pipes that were not on the map when repairing foundation. The delay and the extra man-hours required to work around this immediately inflate the budget.

Fluctuation in material costs and the “Sourcing trap”

In 2026, the supply chain for construction materials will still be volatile. Where it used to be possible to fix a quote for six months, contractors are now forced to include clauses that pass on price increases to the customer.

The prices of wood, insulation materials and, in particular, sustainable technologies such as heat pumps and solar panels can rise by 10% to 15% within a few weeks. If a budget is based on previous year's prices, a gap immediately occurs. In addition, the trend towards “biobased” construction means higher costs, because although these materials are more sustainable in 2026, they are often even more expensive to purchase and more difficult to process.

The optimism prejudice (Planning fallacy)

Psychologically, both clients and professionals tend to underestimate the time and costs required for a project. This is known as the planning fallacy.

In the quote phase, contractors often want to pay the best price to get the job. This is based on the “best-case scenario”: perfect weather, readily available materials and no sick employees. In 2026, with an acute shortage of skilled staff, this scenario is rare. When a specialist team has to wait for a delayed delivery, wage costs continue without progress being made. This “hidden drain” is a silent killer for any maintenance budget.

Lack of specified specifications

A budget often runs out because the initial assignment was too vague. A post such as “exterior painting” seems clear, but without specifying the number of layers, the quality of the paint and the condition of the surface, discussions about additional work arise during execution.

• Scope creep: This phenomenon of increasing the scope of the project during implementation is notorious. “Now that we have the scaffolding, we might as well do the gutters,” is a common phrase that makes costs explode.
• Quality differences: If the client decides during the process that they would prefer HR+++ glass instead of the budgeted HR++ glass, not only the material price increases, but often also the installation time due to the extra weight and thickness.

Regulations and permits in 2026

The government is setting increasingly stringent requirements for maintenance and renovation, especially when it comes to nitrogen emissions and flora and fauna inspections.

For major maintenance in 2026, it is not unusual that an ecological study into the presence of bats or swifts must first take place. If these are found, costly mitigation measures must be taken, such as installing temporary nest boxes and adjusting work schedules. These cost items are often overlooked in the exploratory phase, but can add thousands of euros to the final account.

How to limit budget overruns

The key to a manageable maintenance budget in 2026 lies in a realistic buffer and thorough preparation. Experts recommend including an unforeseen item of 15% to 20% in the budget by default. In addition, it is essential to work with “open calculations” for uncertain factors, so that both parties know where the financial risks lie.

Exceeding budgets is often the result of a lack of transparency and a too rosy view of reality. By investing in a solid architectural report and detailed specifications in advance, you reduce the risk of unpleasant surprises. In the world of maintenance, cheap is often expensive, and a realistic (high) budget is ultimately less painful than an unexpected residual debt.