Heatwave on construction sites: what the 2025 decree changes for the liability of construction companies

For construction companies, the issue now goes beyond the continuity of construction sites: it directly concerns their civil and criminal liability in the event of an accident.

We have just emerged from an unprecedented heatwave: a heatwave now being compared to that of 2003, with up to four consecutive days of red alerts, more than forty million people affected, and a record afternoon temperature broken across France. Schools were closed, hospitals were under strain, and construction sites were forced to improvise. In several departments, prefects even requested the suspension of outdoor work during the hottest hours.

For employers, the crisis didn't end with thermometers. In less than a month, the labor inspectorate conducted nearly 1.600 inspections related to extreme heat—roughly a third of all its inspections since the beginning of the year—resulting in over 1.300 letters of observation and around 100 formal notices to companies whose non-compliance persisted. The administration's message is unambiguous: heat prevention in the workplace is no longer a recommendation, it's a legally enforceable obligation.

For construction companies, the sector most exposed to heat-related accidents, the question is no longer whether the next wave will come, but whether they will be able to prove they were prepared. Because the legal framework has also changed—and it no longer leaves much room for improvisation.

A safety obligation that is not up for debate

The foundation is long-standing and solid: under Article L. 4121-1 of the French Labor Code, employers must take the necessary measures to ensure the safety and protect the health of their employees. The Court of Cassation has long established this as an obligation of result regarding safety. When an accident occurs and the employer was—or should have been—aware of the danger but failed to take measures to protect the employee, this negligence constitutes gross negligence.

The key difference lies in one crucial point: regarding the risk of heat, awareness of the danger is no longer in doubt. Heatwave plans are being implemented regularly, Météo-France's alert levels are public, regulations are now clearly defined—and labor inspectors are monitoring compliance. The hundreds of letters of observation and the hundred or so formal notices issued in June 2026 attest to this: a manager who has failed to organize anything can no longer plead unforeseen circumstances.

The decree of May 27, 2025: a chapter dedicated to extreme heat

Since Decree No. 2025-482 of May 27, 2025, applicable from July 2, 2025, the French Labor Code includes a specific chapter on episodes of intense heat (Articles R. 4463-1 et seq.). Employers must now formally assess the risk associated with heat, both indoors and outdoors, and include this assessment in their single risk assessment document (DUERP). This assessment must be adapted as the heatwave intensifies.

For the construction industry, the requirements are clear. At least three liters of fresh drinking water per day per worker. Reception areas that protect health in case of hazardous weather conditions, or equivalent facilities—shaded areas, shelters. Adaptation of work organization and schedules to limit exposure: earlier start times, more frequent breaks, postponement of the most strenuous tasks. And, during red alerts, a daily reassessment of risks for each workstation, which can lead to a work stoppage if the risk remains too high. It's worth noting, from an economic standpoint, that periods of extreme heat can now qualify for the construction industry's "inclement weather" compensation scheme.

The lesson from the courts: paperwork is not enough

This is perhaps the most important lesson for managers, and it is counterintuitive. What backfires most severely on the employer is not the absence of a DUERP (Single Risk Assessment Document) — it is the DUERP that identifies the risk but whose measures have never been implemented.

The Versailles court illustrated this point in December 2024: a single document clearly mentioned the risk associated with extreme temperatures and stipulated, as a precaution, job rotation. However, no rotation had been organized for an employee working alone, in direct sunlight, in the hottest part of the property, on a day under an orange weather alert. Gross negligence was established after his death. The danger was identified, the preventative measure known—and yet it remained ignored.

Conversely, rulings that dismiss claims of inexcusable negligence all reward the same thing: concrete, appropriate, and demonstrable measures. These include adjusted work schedules, air-conditioned vehicles, training, first-aid equipment, and documented job analyses. The Lyon Judicial Court, in March 2025, dismissed a claim of inexcusable negligence because the employer could demonstrate that all these measures had been implemented, despite outside temperatures exceeding 40°C.

The line is clear: the judge assesses "the rationality, relevance, and appropriateness of the measures actually taken." In other words, a manager's defense is built before the summer, based on traceability, and not after the accident, based on justification.

Anticipate, or be affected

This evolution represents a shift in logic that companies would be wise to grasp quickly. For a long time, heat-related issues were handled on a site's best-laid plan. Now, they fall under a formal, written, and legally binding obligation of prevention, the burden of proof for which rests with the employer.

In practical terms, a company ready for the coming summers is one that has taken a few simple but documented steps: a truly up-to-date Single Risk Assessment Document (DUERP) specifically addressing heat; a heatwave plan designating a responsible person, identifying exposed workstations, and aligned with alert levels; written guidelines on water, working hours, and breaks; training for staff on the signs of heatstroke and the appropriate actions to take; special attention to vulnerable employees and temporary workers, for whom a lack of enhanced training could lead to a presumption of gross negligence. And, above all, the preservation of evidence of all these measures.

None of these actions are beyond our reach. What is costly is not prevention: it is the forced work stoppage, the inspection, and the litigation that goes all the way up to management.

The heatwave put our construction sites to the test. The next one shouldn't further jeopardize the responsibility of those in charge. There's still time to prepare—but the time for improvisation is over.

Opinion piece by Alexandre Lazarègue, lawyer at the Paris Bar (LinkedIn).