A project that began more than a century ago continues to advance thanks to the combination of architecture, engineering, and technology. Today, the Sagrada Familia stands as a powerful example of how innovation enables the construction of what once seemed impossible.
More than 140 years after construction began, the Sagrada Familia continues to push the boundaries of architecture, engineering, and time. It is a project conceived to transcend generations. Construction began in 1882 and, following the death of Antoni Gaudí in 1926, the work was left unfinished – yet firmly defined by his vision.
When Gaudí conceived the towers, he knew that the technical means required to build them did not yet exist. His vision went beyond the capabilities of his time. For this reason, he designed a project for the future, trusting that innovation and technological progress would one day make it possible.
To bring this vision to life, the Sagrada Familia’s technical team developed an innovative construction system based on prestressed stone. This precise and highly efficient modular approach allows the structure to rise level by level through the integration of engineered stone elements and duplex stainless-steel components.
However, this advancement introduced a fundamental engineering question: how to bond stone and steel so that both materials could perform as a single structure.
Given their size and geometric complexity, these elements require bonding systems capable of:
• Integrating different materials
• Absorbing mechanical stresses
• Ensuring long-term stability
The Sagrada Familia initiated the search for a technical solution to address this structural bonding challenge in the central towers. This triggered an extensive analysis and validation process lasting more than eight months, marking the beginning of a collaboration between the Sagrada Familia and Henkel in 2015 and a key turning point in the construction process.
The integration of structural adhesives enabled the full implementation of the modular construction system, transforming the pace of execution. Progress could be achieved up to ten times faster than with traditional methods. What would have once taken 50 to 60 years can now be completed in approximately eight years.
A significant efficiency improvement that redefines how structures of this complexity are built.
In 2020, the pandemic temporarily brought construction to a halt. The project later resumed, adapting to new conditions.
In 2026, the Tower of Jesus Christ, the tallest and last of the six central towers were completed, coinciding with the centenary of Antoni Gaudí’s death. On 10 June 2026, exactly 100 years after his passing, Pope Leo XIV blessed and inaugurated the tower, marking a historic milestone in the project.
With a height of 172.5 meters, the Sagrada Familia is the tallest basilica in the world. Located in Barcelona, just a few kilometers from the sea, it is exposed to demanding environmental conditions:
- Continuous thermal variation, causing expansion and contraction cycles – from around 5°C in winter to over 30°C in summer
- High humidity levels, typically 65% to 75% relative humidity
- A saline environment due to proximity to the Mediterranean Sea
Additional factors include:
- Urban vibrations
- Differential material expansion
- Strict durability requirements
Together, these factors place exceptional technical demands on every construction element.
To address this complexity, construction has evolved towards a modular approach.
The tallest towers are assembled using large, prefabricated blocks – some equivalent to multiple floors – which are stacked level by level.
These elements require bonding solutions capable of:
- Integrating different materials
- Absorbing stresses
- Maintaining structural integrity over time
This approach represents a fundamental shift: what previously required decades can now be achieved in approximately 8 to 10 years.
A transformation that redefines construction methodologies for complex structures.
The challenge required a solution combining the strength of a rigid joint with the ability to absorb micro-movements without failure. This is essential, as stone and steel behave differently under temperature fluctuations, humidity and vibration.
Following this analysis, Henkel identified a two-component epoxy structural adhesives (2K EP) as the optimal solution– one of the most advanced technologies available for structural bonding.
Selected solution: LOCTITE® EA 9497
In total, more than 24 tons of LOCTITE EA 9497 have been used to assemble:
- Over 2,100 stone elementsIn 826 panels
- With an average of ~30 kg per panel
Across the six central towers, this reflects the scale and technical demands of the project.
This solution enables:
- Bonding of stone and steel into a single structural unit
- Uniform stress distribution
- Protection against humidity and salinity
In this context, the adhesive becomes critical – not just as a bonding agent, but as a structural component. It absorbs stresses, prevents relative movement and ensures that stone and steel behave as a single element.
The resulting performance is exceptional. The bonded interface is capable of withstanding the equivalent weight of up to 100,000 people per square meter, illustrating the extraordinary compressive strength of the system.
The solution was validated through a rigorous process lasting more than eight months, including intensive laboratory testing at Henkel facilities in Spain and Germany, as well as independent validation.
At the quarry, each structural element goes through a precise process:
- Integration of metallic components within the stone
- Injection of LOCTITE EA 9497 structural adhesive
- Controlled distribution within the cavities
- Curing under controlled conditions
Within two days, the adhesive transforms from liquid to structural material, ensuring full integration of the materials.
This level of control guarantees that every component meets the exact performance requirements of the project.
Structural adhesives enable high-performance joints capable of withstanding demanding conditions.
Key technologies include:
- Epoxies: maximum strength and durability
- Acrylics: fast curing and substrate tolerance
- Hybrids: optimized balance of performance and sustainability
The collaboration between Henkel and the Sagrada Familia goes far beyond product supply.
Henkel has acted as a global technical partner, providing:
- Adhesive technology
- Validation expertise
- Continuous support throughout all project phases
The bonding solution underwent an exceptionally rigorous validation process – significantly exceeding industry standards – and Henkel has continuously supported the project by adapting production, logistics and supply to evolving needs.
This long-term partnership ensured:
- Supply continuity over more than a decade
- Stability of the solution
- Adaptability within a complex, long-duration project
The Sagrada Familia is not only an architectural icon – it is a demonstration of how innovation enables the realization of ideas ahead of their time.
Today, through the combination of expertise, precision, and advanced technology, Gaudí’s vision continues to take shape.
A vision conceived for future generations.
A challenge brought to life through collaboration.
A dream made reality.
Our experts are here to learn more about your needs.
Our support centre and experts are ready to help you find solutions for your business needs.