Expodach Roof: A Masterpiece of Wood Engineering at the Hannover Exhibition Center

Today, May 26, 2025, the 50th edition begins Ligna Hannover. The Wood Magazine team will document the latest innovations in woodworking technology. Beneath the impressive Expodach structure, one of the most remarkable masterpieces of wood engineering, we explore the legacy that continues to inspire the global wood industry.

Symbol of a vision: Man, Nature, Technology

At the heart of Hannover's exhibition center stands an impressive structure that has become emblematic of the power of wood in contemporary architecture. Built for the EXPO 2000 World Exhibition, this engineering masterpiece perfectly reflects the event's motto: "Man, Nature, Technology".

The "Expodach Roof", as it is known, is much more than just a functional structure. It symbolizes the primordial form of human shelter, transformed by modern engineering into a spectacular manifestation of the possibilities of wood as a durable and versatile building material.

A landmark project for wood engineering

Designed by the architectural firm Herzog + Partner BDA, under the direction of Munich architects Thomas Herzog and Hans Jörg Schrade, the roof represented a major innovation in timber construction in terms of size, structure and design. The structural engineering was carried out by Professor Julius Natterer, a world authority on timber construction, who has made significant contributions to the development of timber construction systems.

The huge structure covers a total area of 16,000 square meters and is composed of ten modular "umbrellas". Each module measures 40×40 meters and is installed more than 20 meters above the ground. These 'umbrellas' are double-curved wooden shells, each supported by a central structure reminiscent of tree trunks in a natural forest.

Innovative technology in execution

What makes this roof truly remarkable is the technology used in its construction. The double-curved wooden shells are made of glued laminated timber beams, forming a skeletal network covered with a waterproof membrane. This approach allowed the creation of complex shapes that would not have been possible with other materials or construction techniques.

The 'ribbed shell' technology developed for this project is one of the latest developments in wooden shell construction. According to experts, this structural form makes it possible to create spectacular roofs using simple plywood and screws. For the central meeting area of EXPO 2000 in Hanover, a wide-span roof structure consisting of ten square "umbrellas" was built.

The design and execution of such a complex structure required the use of advanced 3D modeling and computer-aided manufacturing (CAD/CAM) technologies. There is a significant historical link between Professor Julius Natterer, the principal engineer of the structure, and the development of specialized software for timber construction. Natterer was considered a "spiritual father" of the cadwork system, one of the most important CAD/CAM solutions for timber construction engineering. This type of software has revolutionized the way complex timber structures can be designed, analyzed and fabricated, enabling complex geometric shapes such as those in the Expodach roof.

Functionality integrated into design

The roof design is not only aesthetic but also functional. Each module is divided into four prefabricated wedge-shaped sections, which use a compound slope downward towards the lower center of the square. Rainwater flows naturally downward to the central support columns, where it is collected and brought to the ground. This integration of water management into the design demonstrates the holistic approach of the project.

In addition, the roof acts as a shelter protecting the central square which hosts areas for performances, artists, reconfigurable pavilions, restaurants and spectators. In this way, the structure creates a vibrant community space that is protected from the elements but simultaneously open and welcoming.

Sustainability as a fundamental principle

The theme of the EXPO 2000 World Exposition was "Man, Nature, Technology" and the architects felt that the organic structure of the wooden roof was the perfect construction to embody a natural material from sustainable sources. Wood as a renewable material was the ideal choice to emphasize the sustainability message of the exhibition.

The wooden roof in Hanover demonstrates that wood is not only a traditional material, but also a material of the future, able to meet the challenges of modern and sustainable construction. By using wood as the main structural material, the project highlights the low-carbon potential and environmental benefits of timber construction.

A living legacy for the wood industry

Today, the Expodach Roof remains one of the few structures from EXPO 2000 still standing on the vast grounds of the Deutsche Messe in Hanover. Beneath the impressive wooden roof, halls 32-35 form a compact unit with a special charm.

This structure continues to inspire new generations of architects and engineers, demonstrating the potential of wood to realize grand architectural projects. It is a testament to the vision and expertise of timber specialists and a landmark for the future of sustainable construction.

Meeting the present and future of the wood industry at Ligna Hannover 2025

Today, on the first day of the 50th anniversary of Ligna, the world's leading trade fair for technology in the forestry and wood industry, the Wood Magazine team is here in Hanover to document the latest developments in the sector. It is symbolic that this landmark event is taking place under the roof of Expodach - a structure that, 25 years ago, proved that the limits in timber construction are much further than the specialists imagined.

Over the five days of the fair (26-30 May 2025), more than 1,300 exhibitors from 50 countries and more than 80,000 trade visitors gather to explore the latest innovations in automation and digitization of production processes, sustainable manufacturing and innovations for sustainable construction. The main themes of this edition - digitization in the woodworking sector, green materials processing and prefabrication in timber construction - reflect exactly the same principles that were behind Expodach.

Wood magazine documents these days how the technologies that have enabled the realization of a structure as complex as Expodach continue to evolve. From CAD/CAM systems specialized in wood, to robotic manufacturing technologies and artificial intelligence applied to woodworking, we are witnessing a new revolution in the field. The structure above us reminds us that what seemed impossible 25 years ago can become standard today, and what we see today at Ligna 2025 will shape the future of timber construction for decades to come.