Barcelona builds largest wooden structure with 300 homes

Barcelona’s largest wooden building to house 300 social units

The aftermath of a residential fire in Valencia set the tone when this project was first discussed: 300 social housing units with a wooden structure in Barcelona, presented as the largest building of its kind and an exercise in sustainable construction. The narrative focused on emissions, waste, and passive comfort. The immediate question was about height: what if it burns?

Behind the brochure are hard numbers. According to the project itself, the wooden structure reduces building weight by 75% compared to conventional solutions, while construction waste is halved. More than 80% of construction waste would be recycled through selective sorting into seven fractions, with door-to-door collection for tenants. Energy comes from a heat pump for hot water and central heating, supported by rooftop photovoltaics for common areas, communication cores, and charging points.

That is the technical package. The real debate is different: whether this package can withstand a fully occupied building, rushed maintenance, and forty years of humid climate.

What is a 'rótula' and why does the whole floor depend on it?

The design is not a minor detail. It starts with a four-space unit to which a central rótula (a structural joint that organizes rooms and multiplies connections) is added, trinc by another diagonal one that becomes the kitchen, connected to the external walkway. Another scale of 'rótula' allows double access to the home and creates an independent room. The grid system aims for ambiguous uses, letting tenants decide what is a bedroom and what is a living room based on their needs.

Access is resolved via a community courtyard and a south-facing external walkway, designed as a meeting space for neighbors. The ground floor is separated from the upper structure and functions as urban infrastructure, antiestéticaturing a public pedestrian passage. There is an explicit decision: the 'rótulas' are also structural, and wood is the suggested material for all of them.

Is a multi-story wooden building safe?

Here the issue splits. One side argues that if the building meets current regulations, the risk is the same as any other system, noting that much of Austria is built with wood and exterior insulation without residents living in constant antiestéticar. The other side responds with brick-and-mortar common sense: a wooden house is not the same as a wooden apartment block. In the United States, wooden homes are typically single-family units with private plots and escape routes to the lower floor; stacking apartments changes the scale of the problem.

The most repeated argument is the lack of experience. Without specific anti-fire regulations for wood and a sector that has barely touched the material in collective housing, trust rests on the specific project. The near-unanimous consensus is that the test will not be structural calculation: it will be daily use.

Maintenance: 25-year lifespan against humidity and termites

The second block of criticism is not about flames but water. In humid climates, it is argued, wood requires periodic treatments against insects and rot, and these treatments—varnishes, creosote, and similar—are anything but ecological. Some recall that in high-humidity regions with stone-building traditions, there are no wooden houses, and attempts to introduce them have failed.

Circulating figures speak of useful lifespans of 25 to 30 years, contrasting with the generational heritage left by granite and slate structures. This is where the project is most exposed: social housing endures a level of wear and tenant turnover that private developments do not always face.

Is building with wood cheaper and more eco-friendly?

It depends on where you draw the line for calculations. Those defending the material change point to a fundamental economic reason: manufacturing cement and brick has a higher energy cost than using wood, pushing developers toward it. Those rejecting it highlight the ecological trap: making planks requires cutting trees, and if the structure degrades in three decades, more trees will need to be cut.

The breakdown of the seven waste fractions, recycling above 80%, and the door-to-door collection system are detailed in the project plan. What appears nowhere is the maintenance budget for twenty years. Without that number, comparing costs is debating intentions.

Who signs off on the project?

Behind it is CIERTO ESTUDIO, a team of six architects based in Barcelona founded in 2014, winners of the Ajac X Prize in 2016 for El hogar reversible and first prize in the Illa Glòries competition for La Comunitat Habitacional, their social housing proposal in Plaza de las Glorias. It is a portfolio of competitions, not delivered works, which fuels doubts about what happens when the building is handed over and people start living inside.

Some responses went off-track: the team's appearance, the gender of its members, and disqualifications that touch no calculations. Noise that adds nothing to the technical file.

The analysis stalls exactly where cost engineering should begin. No one disputes that wood is a noble material; no one disputes that it requires care. What is missing is the number that would turn the discussion into a decision: how much it costs to keep a multi-story wooden structure standing and in good condition, per home and per year, for half a century.