Can Skyscrapers Be Built Using Wood Instead of Concrete and Steel?

Currently, the construction world is exploring innovative materials to reduce environmental impacts and improve sustainability. One such material gaining traction is cross-laminated timber (CLT), a modern construction solution that presents an eco-friendly alternative to traditional materials like concrete and steel. However, the feasibility of using wood for skyscrapers remains a topic of debate. This article delves into the possibilities, challenges, and current advancements in mass timber construction.

Theoretical Possibilities

Theoretically, a skyscraper could be built using wood. However, current building codes typically prohibit such structures due to concerns about combustibility. Despite these limitations, the use of CLT offers a promising approach to constructing tall buildings in a sustainable manner.

Current Advancements with CLT

Recently, there has been significant progress in developing CLT as a viable construction material for tall buildings. For instance, the Ascent MKE Building in Milwaukee, Wisconsin, currently stands as the world's tallest mass timber building at 25 stories (284 feet). This structure demonstrates the potential of mass timber construction in achieving sustainable and eco-friendly high-rise buildings.

Ascent MKE Building and Sustainability

The Ascent MKE Building was constructed with support from the USDA Forest Service's Wood Innovations program and fire testing conducted at the Forest Products Laboratory. The use of CLT and glue-laminated timber (glulam) in this project showcases how timber can be engineered to meet stringent fire safety requirements. The burn test demonstrated that oversized glulam columns maintain structural integrity during fires, with some performing well enough to achieve a three-hour fire resistance rating.

Fire Safety and Environmental Impact

While wood is highly combustible, mass timber has several fire-resistant properties. For instance, charring occurs predictably, protecting internal layers and making the structure self-extinguishing once charred to a certain depth. Moreover, wood buildings store considerable amounts of carbon, reducing the need for fossil energy in construction. This makes them attractive for builders and consumers seeking sustainable solutions.

Challenges and Considerations

The primary challenge in using wood for skyscrapers is regulatory. Current building codes do not permit the use of combustible materials for high-rise construction. However, ongoing research and testing by organizations like the USDA Forest Service are paving the way for future code changes and advancements in the industry.

Future Outlook for Mass Timber

With continued innovation and support from government and private sectors, mass timber is poised to revolutionize the construction industry. As the world seeks more sustainable building solutions, mass timber presents a promising alternative to traditional materials like concrete and steel. It supports healthy forest management and reduces the risk of wildfires by removing excess trees from overpopulated forests. Additionally, it promotes the development of new markets for wood products, fostering a more sustainable future.

Concluding Thoughts

While the construction of skyscrapers using wood is not yet a reality, the advancements in mass timber construction, particularly with CLT, offer hope for a more sustainable future in the construction industry. Continued research and regulatory adjustments will be key to unlocking the full potential of mass timber in building tall structures. As technology and materials continue to evolve, we may see more innovative applications of wood in high-rise construction.