The Era of Mass Timber Wood Skyscrapers is here!

July 22, 2022

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The birth of skyscrapers in the 1880s was a defining moment in the history of architecture, engineering and construction. Although skyscrapers were first used as office spaces, they have become a popular housing option. High rises can increase the density of cities by providing more housing in a given area. They can also define a city’s skyline and become the nucleus of an entire tourism industry.

Concrete and Steel in Skyscrapers

Every high rise and skyscraper around the world is built with concrete and steel; two of the most versatile and valuable building materials. However, they are energy intensive materials with massive carbon footprints. In the search for more environmentally friendly skyscrapers, designers have turned to good old-fashioned wood.

The Stadthaus in London, which was built in 2009, was one of the first high rises made of wood. It has 9 storeys and stands 99ft or 30m tall.
Brock Commons in Canada, which was built in 2017, broke records as the tallest contemporary wood building. It has 18 storeys and stands 190ft or 58m tall.
Mjostarnet in Norway, which was built in 2019, is now the tallest timber building in the world. It has 18 storeys and stands 280ft or 85m tall.

Environmentally-Friendly Skyscrapers

Wood also lacks concrete’s compressive strength which is the ability to withstand compression or pushing forces. To improve the properties of wood and make it even stronger than steel and concrete, moisture resistant glues are added in between layers of wood to make engineered mass timber products. Some examples are:

Glulam or glued laminated timber which consists of several layers of wood with the grain running in one direction.
Cross laminated timber or CLT consists of layers of wood in alternating directions.
Laminated veneer lumber or LVL consists of thin layers of wood all stacked in the same direction.

Advantages of Wood Skyscrapers

Cost-Effectiveness: Mass timber structural members, such as floor slabs and columns, can be cheaper than steel and concrete, especially in volatile markets.
Faster Construction: Mass timber projects are approximately 25% faster to construct than concrete and steel projects.
Eco-Friendly: Sustainably harvested wood is more environmentally friendly than concrete or steel, with mass timber construction often being carbon neutral or carbon negative. That carbon is locked into the tree so long as it doesn’t rot or burn. This can reduce the overall carbon footprint of buildings. Wood for Good, a campaign by the timber industry, claims that producing a ton of bricks requires four times the amount of energy as a ton of softwood, while concrete requires five times, steel 24 times, and aluminum 126 times.
Fire Resistance: Mass timber exhibits superior fire resistance compared to steel, as charred wood can retain much of its structural integrity.

Disadvantages of Wood Skyscrapers

Strength Limitations: Mass timber is not as resilient against corrosive substances as concrete and steel, so some components, like foundations and structural cores, still require traditional materials.
Code Restrictions: While the height limit for mass timber buildings has increased, taller structures must conceal timber members due to fire safety concerns.
Psychological Barriers: Some investors and the general public may perceive mass timber high-rises as risky or flimsy.
Sustainability Concerns: Ensuring sustainable harvesting practices for mass timber remains essential, especially in regions with looser regulations.

Conclusion

In conclusion, the era of mass timber wood skyscrapers is upon us, with numerous impressive buildings already standing tall. Mass timber offers cost-effectiveness, faster construction, eco-friendliness, and excellent fire resistance. However, certain limitations, code restrictions, psychological barriers, and sustainability concerns require careful consideration.

As mass timber technology continues to improve, we can look forward to even more innovative and sustainable skyscrapers. However, achieving energy-efficient and environmentally-friendly high-rises will still require thoughtful design and planning.