Architects specify wood for many reasons, including cost, ease and efficiency of construction, design versatility, and sustainability—as well as its beauty and the innate appeal of nature and natural materials. Innovative new technologies and building systems are also leading to the increased use of wood as a structural material, not only in houses, schools, and other traditional applications, but in larger, taller, and more visionary wood buildings. But even as the use of wood is expanding, one significant characteristic of wood buildings is often underestimated: their durability.

If buildings are designed with local climate impacts in mind, wood buildings stand the test of time. When used in tandem with proper envelope design, building with wood can reduce future maintenance and repair costs. Good design also ensures that wood materials last and weather well in various climates, including those with high humidity, frequent sun, and heavy rain. Wood has the ability to absorb and release moisture and is resistant to many of the chemicals and conditions that adversely affect other building materials.

Examples of wood buildings that have stood for centuries exist all over the world, including the Horyu-ji temple in Ikaruga, Japan, built in the eighth century, stave churches in Norway, including one in Urnes built in 1150, and many more. Today, wood is being used in a wider range of buildings than would have been possible even 20 years ago. Next-generation lumber and mass timber products, such as glue-laminated timber (glulam), cross laminated timber (CLT), and nail-laminated timber, along with a variety of structural composite lumber products, are enabling increased dimensional stability and strength, and greater long-span capabilities.

These advances are leading to taller, highly innovative wood buildings. As of December 2020, 1,060 mass timber projects had been constructed or were in design in all 50 states, in the multi-family, commercial, or institutional categories. *This total includes modern mass timber and post-and-beam structures built since 2013 (https://www.woodworks.org/publications-media/building-trends-mass-timber/).

Central to Montréal’s up and coming Griffintown neighborhood, the all-wood Arbora project is the largest complex of its kind in the world, to date, built from mass timber. With its three 8-story buildings, 273 condominiums, 30 townhouses, and 130 rental units, Arbora’s mass-timber design is unprecedented in its size and features an exposed wooden post-and-beam design in every unit, a unique selling feature for residents. Catalyst, in Washington state, is the first cross-laminated timber (CLT) office building constructed in the region and is also designed to Passive House principles and to achieve zero-carbon and zero-energy certification from the International Living Future Institute (ILFI), making it a leading example of sustainable building design. Intro, of Cleveland, Ohio is a mass timber construction project combining 288 homes, 35,000 square feet of retail, and 25,000 square feet of private amenities, an innovative design creating a community for people to live, work, and socialize. Carbon 12, in Portland, Oregon, provides residents with modern luxury, sustainable design and state-of-the-art technology. Constructed with sustainably harvested and certified CLT, Carbon 12 was one of the tallest buildings of its kind in North America, when it was completed in 2018.

As with any structural material, perhaps the most important single factor to a long and useful service life is effective design. Extensive research and documented experience have led to a number of proven strategies for ensuring that wood material reaches its full potential for longevity. This course outlines the informed design, specification, detailing, and quality control during construction, installation, and maintenance that are collectively key to achieving maximum durability in today’s wood construction.

Photo courtesy of Josh Meister and Philip Spears

Emory Point is a vibrant, mixed-use urban infill development located in the historic Druid Hills neighborhood of Atlanta, Georgia. Emory Point’s first phase consists of three buildings with 443 luxury apartments and 80,000 square feet of retail and restaurants. Emory Point’s developer realized significant cost savings and met an aggressive construction schedule by using wood framing to build the four- and five-story buildings in this $60-million project.

Arbora, in Montreal, Québec, is the largest complex in the world built from mass timber, as of 2020. The nearly 600,000 square-foot-project includes 273 condominiums, 30 townhouses, and 130 rental units for a total of over 430 residential units. The project also offers retail space on the ground floor of one of the three buildings. Wood-frame and mass-timber construction offers sustainability, value, and cost-savings. With its three 8-story buildings, Arbora’s mass-timber design is unprecedented in its size and features an exposed wooden post-and-beam design in every unit. For all three buildings, structural construction is entirely from mass timber. The bearing partition walls of the load resistance system are built in cross-laminated timber (CLT). The gravitational/vertical load resistance system is a post and beam structure of glue-laminated wood (glulam). The mass-timber panels are held together by wooden tongues or nailed metal, and self-tapping screws are used to assemble the beams and columns. Timber components were shipped to the site from a plant in Chibougamau, Québec in the form of prefabricated wood cut to the required dimensions, with openings for doors and windows, using computerized numerical control (CNC) machinery. All of this gave the building assembly a tight, efficient, and precise fit.

Photo courtesy Nordic Structures