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Next to Carbon 12, an eight-story mass-timber mixed-use building in North Portland, the Kaiser Group and PATH Architecture are sticking with wood.

The Canyons, at the corner of North Williams Avenue and Ivy Street, will also feature cross-laminated timber (CLT). It will be six stories and offer market-rate apartments as well as substantial commercial space. But The Canyons won’t be a carbon copy.

鈥淚t’s a different type of structure,鈥� said project architect Emily Dawson of PATH Architecture. 鈥淭his is much more like a conventional multifamily project where we don’t have a post-and-beam structure like a lot of the CLT projects going on right now.鈥�

R&H Construction is the general contractor for The Canyons. Crews broke ground in February on what will eventually be a 65-foot-tall building with 70 residential units. In total, there will be 110,000 square feet of floor space. It is designed for seniors, but there won’t be an age restriction. The team sought to offer physically accessible accommodations within a vibrant urban environment. Light-filled apartments will have open floor plans and modern designs. Plus, a resident paramedic will be available 24 hours a day, seven days a week.

Then there’s the unique open-air Alleywalk marketplace that will feature two separate buildings with several small businesses. These micro-retail spaces will range from 250 to 420 square feet.

Also, officials are working to establish partnerships with Legacy Health, New Seasons Market and others to help residents save on dining and health care costs.

The project is designed in part around the concept of intergenerational living. To that end, the team hopes to attract a Montessori school or a similar tenant.

On the design and engineering front, Dawson noted, there have been plenty of lessons learned from PATH Architecture’s experience with Carbon 12 to apply to The Canyons. While both buildings use CLT floor panels (fabricated by British Columbia-based Structurlam), there are more differences than similarities between them. Carbon 12, for instance, features a structural steel core, while The Canyons is being built more or less as a conventional building with a post-tensioned concrete podium.

One unique use of CLT panels in The Canyons will be in an interior atrium structure that links all five stories of apartments through the building’s open-air center. Zigzagging walkways on each floor will bounce from entryway to entryway along the length of the building. Those CLT walkways will be supported by other panels, but at skewed angles to form a never-before-seen load-bearing structure.

To obtain a final building permit, Dawson and her team had the walkway design tested by the Tallwood Design Institute at Oregon State University.

鈥淏ecause they sit along each corridor wall, but sit at this kind of skewed angle, it creates what is called torsional shear through the panel,鈥� Dawson said. 鈥淚t’s shear moving through the panel in a way that we don’t have tested values that we can pull from charts.鈥�

Under guidelines in Chapter 17 of the state building code, an exact copy of the atrium design was fabricated and sent to the Tallwood Design Institute lab for load-bearing tests. The results showed the design could bear at least three times its intended structural load 鈥� the lab ran out of weight to add after roughly 60,000 pounds.

鈥淥ur panels recovered to the level at which it passed the two-times test,鈥� Dawson said. 鈥淓ven when we took it to three times, we actually tried to break the panel but we couldn’t get it to failure.鈥�

Crews from R2M2 Rebar & Stressing and Marion Construction are working below grade to construct the building’s underground parking structure, foundation and core.

鈥淲e are pouring structural concrete in the basement right now,鈥� said Adam Peterson, senior project manager for R&H Construction. 鈥淲ork on most of our foundations are complete. We are working on columns and walls, and right now we’re trending a little bit ahead of schedule. We will be in structural concrete through summer and starting wood framing in September and then the CLT will go up quite quickly.鈥�

Cross-laminated timber offers multiple benefits, Dawson said.

鈥淭he first thing was the schedule advantages and ease of construction and lack of complications,鈥� she said. 鈥淭he second is the look; people just really love being in those spaces. It looks really beautiful and it feels so good to have that exposed wood. So, we see that as a differentiator on the market, and as a building owner it was really important to us.鈥�

Completion is scheduled for fall 2020.