Henkel technology supports completion of the Sagrada Familia’s central towers

The construction of the Sagrada Familia’s central towers marks the most complex structural challenge in the basilica’s history. An advanced Loctite solution from Henkel has been instrumental in meeting this challenge and serves as an invisible enabler of this architectural milestone. Over more than a decade of collaboration, Henkel has contributed not only its high-performance structural adhesive, Loctite EA 9497, but also extensive testing and validation beyond standard requirements, dedicated technical expertise, and continuous supply tailored to the project’s evolving needs.

“This project embodies what we do at Henkel Adhesive Technologies. We work with our customers to turn their vision into reality. The Sagrada Família shows what’s possible when the right partners come together. We make it happen by delivering solutions that perform where it matters most. As Henkel marks 150 years, it’s a powerful reminder that progress happens when innovation and collaboration endure across generations,” explained Mark Dorn, Executive Vice President Henkel Adhesive Technologies.

The adhesive that bonds stone and steel

Behind the striking appearance of the towers lies a crucial yet unseen element: the adhesive that bonds stone and steel components, enabling them to perform as a single structural unit. Applied in liquid form, the adhesive adapts to the bonding surfaces, fills cavities, and creates a durable connection between stone and steel components. It then undergoes a curing process of around 24 hours, during which the panels are kept under stable thermal conditions.

To realize Gaudí’s vision – well beyond the technical possibilities of his time – the Sagrada Familia introduced a modular construction approach that has accelerated processes by up to a factor of 10 compared with traditional methods. Henkel’s adhesive expertise has been instrumental in making this approach viable, allowing stone and steel to function as a single structural element, reducing construction time while maintaining full safety and structural integrity, and enabling completion of the towers in the centenary year of Gaudí’s death. In total, 24 tons of Loctite adhesive have been used, with around 30 kilograms applied per panel on average. The six central towers comprise 826 panels and more than 2,100 stone elements.

Engineered for demanding conditions

Loctite EA 9497 has demonstrated reliable performance and a carefully balanced combination of rigidity and flexibility under highly demanding conditions: Located approximately 2.5 kilometers from the Mediterranean Sea, the Sagrada Familia is continuously exposed to a saline environment that promotes corrosion. High relative humidity levels in Barcelona, typically between 65% and 75%, further increase environmental stress. Temperature variations add another layer of complexity, ranging from about 5°C in winter to more than 30°C in summer, resulting in continuous expansion and contraction cycles. In addition, two metro lines running close to the basilica generate constant vibrations that are transmitted to the structure.

Exceptional strength at scale

The bonded structure can withstand loads equivalent to up to 100,000 people per square meter. This level of strength has been critical in supporting the cross atop the Tower of Jesus Christ, the tallest structure within the complex. While the cross itself does not incorporate adhesives, its stability depends on the robustness of the supporting structure. As a result, the Sagrada Familia now stands as the world’s tallest religious building, reaching 172.5 meters and surpassing Ulm Minster in Germany.

Innovation supporting Gaudí’s legacy

Henkel’s collaboration with the Sagrada Familia demonstrates how modern engineering can be seamlessly integrated into a project that began more than 140 years ago, preserving Gaudí’s original vision while enabling its realization through advanced technologies.

150 years of innovation

This milestone coincides with Henkel’s 150^th anniversary, reinforcing its commitment to innovation under the motto “Future? Ready!”. The application of Loctite technology at the Sagrada Familia highlights the company’s capability to enable complex, forward-looking construction projects.