Could we build a wooden skyscraper? - Stefan Al

Summary

Mjøstårnet, the world's tallest wooden building at 85 meters, blends seamlessly into the Norwegian countryside. Built with innovative materials like cross-laminated timber (CLT) and glue-laminated timber (glulam), this structure showcases wood’s surprising strength and versatility. These engineered woods offer advantages over traditional materials such as concrete and steel, including reduced carbon footprint, easier construction, and resilience to natural disasters. While not fully wooden, Mjøstårnet demonstrates how wood can contribute to sustainable, eco-friendly architecture, lowering construction's environmental impact and offering a promising future for greener building practices.

Takeaways

• 😀 Mjøstårnet is the world’s tallest wooden building, standing 85 meters tall in Norway, showcasing modern architecture in a rural setting.
• 🌲 The building is constructed almost entirely from local wood, sourced from nearby forests, blending well with the surrounding natural landscape.
• 🛠️ Engineers once believed building wooden structures over six stories was impossible due to wood’s vulnerability to certain forces, but advances in engineered wood have changed that.
• 🔧 Glue laminated timber (glulam) and cross-laminated timber (CLT) are two key innovations that make wooden buildings structurally strong enough to compete with steel and concrete.
• 🪵 CLT is made by gluing wood layers in alternating orientations, enhancing wood’s strength in every direction, while glulam creates strong beams by gluing boards in the same direction.
• 🌍 CLT and glulam have environmental advantages, being lighter than concrete, easier to work with, and more sustainable as they reduce construction waste and carbon emissions.
• 🏗️ Wooden buildings using CLT and glulam can be prefabricated, speeding up construction, reducing noise, and making the process more efficient compared to traditional concrete buildings.
• ⏳ Wood offers better resilience to natural disasters, as it’s easier to replace damaged panels compared to cracked concrete or melted steel, and it’s more fire-resistant due to the charring effect.
• 🌱 Timber is a renewable resource and can be carbon-neutral if sustainably sourced, helping to reduce the carbon footprint of construction compared to concrete and steel.
• 📏 While CLT and glulam are strong and efficient for buildings under 30 stories, they are not yet suitable for skyscrapers due to the material's limits in comparison to steel and concrete.

Q & A

What is Mjøstårnet, and why is it significant?

Mjøstårnet is the world’s tallest wooden building, standing 85 meters tall in Norway. Its significance lies in its innovative use of engineered wood, such as Cross-Laminated Timber (CLT) and Glued Laminated Timber (Glulam), making it an impressive example of modern sustainable architecture.

How does Mjøstårnet blend into its surroundings despite its height?

Mjøstårnet blends into the rural Norwegian landscape because it is made almost entirely from wood sourced from neighboring forests. This gives the building a natural aesthetic that complements the surrounding forested farmlands.

What was the primary challenge in building tall wooden structures before the invention of engineered wood?

Before engineered wood materials like CLT and Glulam, it was believed that it was impossible to build tall wooden structures because traditional lumber lacked the necessary tensile and compressive strength to withstand the forces at high altitudes, such as wind.

What is Cross-Laminated Timber (CLT), and how does it enhance the strength of wood?

Cross-Laminated Timber (CLT) is an engineered wood product where boards are glued together in alternating orientations, with each layer set at 90 degrees to its neighbors. This process gives CLT wood enhanced structural rigidity in all directions, allowing it to bear loads up to 20 times heavier than traditional lumber.

What is the primary advantage of Glued Laminated Timber (Glulam) over traditional timber?

Glued Laminated Timber (Glulam) is made by gluing boards together in the same direction, forming massive beams with tensile strength comparable to steel. This makes it especially suitable for load-bearing beams and columns, providing superior strength along one direction.

How does CLT compare to Glulam in terms of versatility and strength?

CLT is more versatile than Glulam, as it provides strength in all directions and is better suited for structural panels. Glulam, on the other hand, excels in strength along one axis, making it ideal for beams and columns but less flexible than CLT.

What are the key construction benefits of using CLT and Glulam materials?

The use of CLT and Glulam materials results in lighter construction, requiring smaller cranes, foundations, and fewer workers. It also enables faster and quieter construction due to the prefabrication of parts, and it generates less waste while being more biodegradable than concrete.

What are the disaster resilience benefits of buildings made from CLT and Glulam?

CLT and Glulam buildings are more resilient to natural disasters like earthquakes and fires. In earthquakes, cracked wood panels can be replaced easily, and in fires, the charred outer layers of CLT provide insulation, keeping the inner layers intact for several hours, offering sufficient time for evacuation.

How does timber compare to concrete and steel in terms of environmental impact?

Timber, being a renewable resource, can be carbon-neutral if trees are replanted to replace those cut down. Unlike steel and concrete, which are significant contributors to carbon emissions, timber buildings have a smaller carbon footprint and are more energy-efficient for heating and cooling.

Why is it unlikely that a purely wooden structure could support a 40-story skyscraper?

Although CLT and Glulam have impressive strength properties, they are not as strong as steel or concrete. A building purely made of wood would not be able to support the necessary load and structural demands of a 40-story skyscraper, which requires materials with higher strength and durability.