Wooden buildings: building ecologically without playing with fire

On the one hand, the climate emergency demands that we abandon concrete, a major CO2 emitter, in favor of bio-based materials (wood, straw, hemp) with a very low carbon footprint. On the other hand, an age-old fear persists: that of living in structures that we imagine to be flammable.

At the second fire prevention conference, held Thursday in Paris, the challenge was to reconcile these two worlds.

"For a long time, we built concrete bunkers that didn't burn, but today, we are changing the paradigm," summarizes Gérard Senior, an architect who was present during the discussions.

For him, the resurgence of wood "is shaking things up", but fire resistance remains "the public's primary concern".

"Aesthetics and carbon footprint are no longer enough, we need to reassure people about the protection of lives," he adds, referring to the striking images of recent fires like the one in Grésy-sur-Aix (Savoie) in August 2024, a textbook case of wood construction.

Regulatory turning point

To manage this transition, the State had to clarify the rules of the game.

Present at the conference, the interministerial delegate for forests, wood and its uses, Jean-Michel Servant, stressed the importance of the decree of November 19, "which has established the doctrine" for medium and high-rise buildings.

"We were in a state of uncertainty that was holding back developers, but with this decree we have enshrined the possibility of using solutions with equivalent effects, notably validating the doctrine of thermal barriers," explains the government official. In practical terms, wood is permitted for structural use, but it must be protected.

"The objective is zero ambiguity for the rescue services: wood must not be synonymous with additional risk," he specifies, describing this text as "an act of maturity" for the industry.

On the ground, this change in doctrine is being driven by a new wave of professionals.

Marie Toulemont, a young engineer, embodies this "wood generation" which no longer sees concrete as the unsurpassable standard.

"For my generation, concrete is almost a climatic anomaly, whereas we have learned to calculate with living things," she says.

Beyond ideology, she counters the fear of fire with technical arguments. "Wood burns, that's undeniable, but it behaves much more predictably than steel, which melts and twists suddenly under the heat," the engineer asserts.

"Added fuel charge"

This reassuring discourse sometimes clashes with the operational reality faced by firefighters. For them, the massive influx of natural materials into residential buildings alters intervention tactics.

"This is what we call the added fuel load," explains Lieutenant-Colonel Pierre Prévost, from the prevention commission of the National Federation of Firefighters of France (FNSPF).

His concern is not about the material itself, but about its widespread use in large-scale buildings.

"The priority remains the evacuation of occupants before collapse, and the widespread use of wood in dense buildings can complicate fire detection," the officer warns.

Ultimately, everything depends on the quality of the execution on the construction site.

Jean-Baptiste Aurel, quality engineer, points out that "the risk does not come so much from the material as from the way it is assembled".

According to him, the danger is invisible. "You have to pay attention to the details, the joints, and avoid gaps where the fire could spread, hidden, inside the partitions," he warns.

Increased vigilance requires an increasingly skilled and therefore scarce workforce.

The emerging compromise is one of mixed construction: a concrete core for the stairwells, and a timber frame for the rest.

"We need to change our approach and accept that the building of tomorrow will be hybrid," concludes architect Gérard Senior.