Building Hi-Rises in Wood
Should Our Multi-Story and Commercial Buildings be Built of Wood?
When we think of commercial and multi-story construction, steel, brick and concrete usually comes to mind. After all, since the late 1800s, our cities have become super muscular, highly dependent on these products. But their toll on our planet and its environment has become devastating. Do we have alternatives to build our future construction growth, expected to increase by 40% by 2040.
Wood is man’s oldest building material as he emerged from caves. Heavy timber has been the major component of every civilization, even the ancient Egyptian’s, famous for their stone pyramids, built their cities extensively out of wood with mud exteriors. Most of the medieval cathedrals we think of as stone masonry, are mostly heavy timber clad in granite and masonry skin.
The 20th century relegated timber construction to residential and low-rise structures such as light commercial, institutions, schools and churches.
Sustainability and environmentally correct construction materials have become a focus of the 21st-century. Tall buildings of timber are in the works throughout Europe. Commercial construction and multi-story buildings, even up to 10 stories, can benefit from the use of wood heavy timber.
Technology has shown that heavy timber construction, sometimes called mass timber, allows precise construction and economic production of members faster, low energy production, sustainably harvested and with less manual labor. Timber is local, and production processing can be minimal compared to steel or concrete.
Heavy timber High Rises using Cross Laminated Timber, CLT
Durability and sustainability are essential today. Cross Laminated Timber, CLT, is very popular as an alternative to heavy steel and concrete construction. This engineered wood product with multiple layers of lumber glued together is similar to what we called Glue-Lam beams but stronger and more durable. CLT has been around for 100 years but is now more common as our old-growth wood forests are protected, and harvested timber, with all its imperfections, becomes more popular.
We all know that Wood is a renewable product and managing forests for these recyclable and biodegradable products is essential to our future. An average of 8 million seedlings are planted each year on the Pacific West Coast alone. Because of its insect resistance and tolerance to fire and flooding, harvesting trees such as Cedar hold our future and help end our dependence on petroleum products.
In downtown Milwaukee a 25 story 259-unit high-rise is under construction using mass timber, or cross laminated timber CLT. A mass timber high-rise in Sydney Australia is planned at 590 feet.
The buildings will go up faster with a lower carbon footprint than conventional steel and concrete construction. And, this creates a more attractive home-like feeling when interiors of heavy timber construction can be exposed.
While the pandemic has telescoped supply lines everywhere, depending on steel and concrete that has escalated in price greater than wood and supply lines are shorter, reconsidering wood for residential fire-resistant construction and multi-story high-rise makes a lot of sense.
Chris d Craiker, AIA/NCARB has designed 4 hour fire-rated wood structures