OXO Architects, timber architecture and construction in Paris

Timber construction uses wood as the load-bearing structure of the building, alone or in a hybrid system (wood-concrete, wood-steel). It reduces weight and carbon footprint, speeds up the site and brings a renewable resource to the heart of the building. At OXO, it answers first to the context of the site.

The question is legitimate, and the answer rests on a paradox: wood burns, yet it resists. A glued-laminated or solid timber beam consumes slowly at the surface, forming a charring layer of roughly 0.7 mm per minute that insulates the core and protects it. The intact section keeps its load-bearing capacity in a predictable, calculable way: we size the member so that after the required fire-resistance rating (30, 60 or 90 minutes depending on use), the structure still stands. Steel, by contrast, does not burn but buckles: around 500°C it loses its strength and collapses without warning. Add to this compartmentation, smoke control and, where regulations require it, sprinklers. Our timber buildings, from the Lycée Jean Moulin in Revin to Ecotone in Arcueil, meet the same public-building and housing requirements as concrete. Fire safety is not a magical property of the material: it is the result of design, calculation and workmanship. That is precisely where our craft is decided.

Let us be honest: yes, the structural package can show a higher initial cost on some projects. But that figure per square metre of shell tells you almost nothing about the real cost. Off-site prefabrication changes the equation: elements arrive ready to assemble, the site is shortened by several months, stays cleaner, with less disturbance for neighbours and fewer interim interest charges to pay. A lightweight structure eases foundations and transport. On the Jean Moulin school in Revin, as at Marcel Paul (Saint-Herblain), this logic made timber relevant, never imposed. The real debate is not the price per square metre of structure, it is the time horizon: over the building's life cycle, the balance often tips in favour of timber. We are not the architects of a material, but of good situations. Decarbonisation, indoor comfort, speed of delivery: these values are part of the real cost of a building. Timber when the context calls for it, after ten years of research, never by dogma.

Timber worries people because they believe it fragile. The facts say otherwise: medieval timber-framed churches and centuries-old farmhouses have stood for six or eight hundred years. Their secret is no miracle product, it is a principle: protected timber. A generous roof overhang, a base that lifts the wood off the ground, an air gap that ventilates the cladding, and careful treatment of the singular points (bearings, junctions, penetrations). A structure conceived this way asks for little upkeep: a periodic inspection, occasionally a local repair. The greying of cladding, so often feared, is purely aesthetic: it is the patina of time, not a pathology. Timber turns grey, it does not grow weaker. We choose each species and each finish according to the real exposure of the facade, from Douglas fir to larch, from charred to pre-greyed wood. At OXO, from the Jean Moulin school in Revin to Ecotone Arcueil, more than ten years of research have taught us this: durability is not bought, it is drawn. It is decided in the detail, in the right line.

Let us be frank: water is not timber's enemy, stagnation is. Wood that is regularly wetted by rain then dried by the air does not suffer: this is the case for every exposed cladding. What harms timber is moisture that stays trapped, unable to escape. The first barrier is therefore not a product, it is the drawing: steering the water, providing air gaps, avoiding water traps, caring for every junction. We then reason in use classes, from 1 to 4, matching species and treatment to the real exposure of each wall. Structural timber reaches the site dried, at a controlled and monitored moisture content, the condition of its stability. Occasional wetting is harmless, prolonged stagnation cannot be undone. This is exactly where our demand plays out: the right detail, drawn before it is built. Timber does not fear the rain when the architecture, for its part, has planned where the water will go.

Comfort is not declared, it is measured and felt. Wood has low intrinsic inertia, but combined with screeds and good insulation it provides a thermal phase shift that delays the entry of summer heat by several hours. Above all, its low conductivity makes it warm to the touch, without the cold-wall sensation of concrete, and it regulates humidity by absorbing then releasing moisture from the air. Acoustics, often cited as the weak point, is mastered through design: walls and floors built as mass-spring-mass, heavy floating screeds, resilient strips that cut airborne transmission and impact noise. As for indoor air quality, untreated or finely finished wood, combined with controlled ventilation, limits volatile compounds. At the Lycée Jean Moulin as at Marcel Paul, this comfort in use, thermal, acoustic, sensory, is what remains once the construction site is forgotten. That is what we seek: not a fashionable material, but the right situation for those who inhabit the place.

Yes, but not by magic. As it grows, a tree captures CO2 through photosynthesis and stores it as biogenic carbon. Used in a structure, that wood keeps this carbon sequestered for the whole life of the building, decades during which it stays out of the atmosphere. Add to this a low embodied energy: turning a trunk into a beam takes far less energy than producing cement or steel, two materials whose manufacture emits enormous amounts of CO2. So much for the promise.

Honesty calls for nuance. The real balance depends on the origin (a sustainably managed forest, located nearby), on transport, on how the wood is used, and above all on end of life: wood that is burned or buried releases its carbon, wood that is reused prolongs its storage. Only a full life cycle analysis, the kind RE2020 requires, tells the truth. This is our lens at OXO: we think in terms of global carbon cost, from the ground to deconstruction. At the Jean Moulin high school in Revin, the timber structure was not an argument, it was the result of that calculation. Wood is virtuous when it is well conceived, not because it is wood.

No, and that is the heart of our position. At OXO, we are not the architects of a material, but of good situations. Wood is a major lever for decarbonization, not a single answer. Wanting to build everything in wood would be a dogma, and a dogma closes its eyes to context.

To decarbonize is to put the right material in the right place. A mixed timber-concrete structure combines the lightness and carbon storage of the first with the thermal mass and strength of the second, each where it serves best. Low-carbon concrete, the reuse of existing materials, and material sobriety (simply using less matter) count as much as the species chosen. And the most ecological gesture is sometimes to not build at all: to renovate what exists rather than demolish, because the least emitting building is the one we never raise. This logic guides our projects, from the decarbonization of Boulogne Seine Gourmande to the Ecotone in Arcueil. Wood takes its rightful place there, generous but measured. For us, loving wood also means knowing when to prefer something else.

The question is fair, and we take it seriously. But we must separate two realities that the word wood tends to blur. Deforestation destroys an ecosystem: a tropical forest is cleared for soy or pasture, and nothing grows back. Sustainable forestry is the opposite: a managed forest, harvested through selective cutting, that regenerates and, in Europe, expands every year. Responsible construction timber comes from these forests, traced by the PEFC and FSC labels, which certify the chain from the plot onward. We favour local sourcing and short supply chains: wood that has crossed the planet loses its ecological meaning. A point often overlooked: a managed forest, where mature trees are harvested and replaced by young shoots hungry for carbon, captures more than a forest left to reach maturity and equilibrium. Yet let us stay clear eyed: virtuous wood presupposes virtuous management, it is never automatic, and vigilance over origin remains our duty. In the end, building in responsible wood gives economic value to the living forest. In a world that covets it, this offers the forest a tangible reason to exist and to be preserved.

No, never on principle, and that is a point of honour. We love wood, deeply, after more than ten years of research on this material. But we are not the architects of a material: we are the architects of good situations. Wood asserts itself when the landscape and the age call for it. On a forest site it becomes structurally and emotionally self evident: the Jean Moulin high school in Revin, set in the Meuse valley, Ecotone in Arcueil, the A10 tower in Tours. Elsewhere, it is the place that dictates the right matter: local stone quarried nearby, raw earth from the site, low carbon concrete when the span demands it, the reuse of materials already present. Often these matters converse within a single project, wood as structure, another as base or as skin. To impose wood everywhere would be a dogma, and dogma is the enemy of rightful architecture. Our commitment is not to a species, but to coherence: the right material, in the right place, for the right reason. This is how a building is born that truly belongs to its site, and that stays just over time.

Yes. As early as 2016, the Lycée Jean Moulin let us build at large scale. Today, projects such as Kaskade in Lille or the Tour A10 in Tours carry the research towards verticality, in timber or hybrid structures, lighter and decarbonated.

The Lycée Jean Moulin in Revin (delivered, in the Ardennes forest), Marcel Paul in Saint-Herblain (a mostly timber structure), Pixel Tours, Boulogne Seine Gourmande, Kaskade in Lille, Ecotone Arcueil and the Tour A10 in Tours. A trajectory of over ten years, built or in study.