Aaron Locke

Built on the former site of Shoreline, Washington’s post office, The Postmark is a new 243-unit, mid-rise apartment community 10 miles north of downtown Seattle, where an impending extension of the city’s light rail system is driving growth for housing.

Developer The Wolff Co. partnered with construction firm Katerra to design the two-building, five-story project, which is among the first developments in the country to use cross-laminated timber (CLT), or large-scale, prefabricated, solid engineered wood panels, for the floor and ceiling assemblies. It is Katerra’s first residential CLT project, utilizing European CLT prior to its Spokane Valley, Washington–based factory being operational in 2019.

Courtesy Katerra

The technology-driven construction firm used virtual design and construction as well as 3D modeling to create a building prototype and manufactured the components completely off-site. The prefabricated panels arrived on-site with all joints precut, to extremely low tolerances, enabling the crew to install an entire 30,000-square-foot floor in three days.

Beyond the aesthetic value of the exposed wood ceilings and beams in the units and communal areas, the European CLT, along with glulam beams, used for the floor slabs and roof structures reduces structural loads and increases build efficiency when compared with concrete and steel, according to the firm.