Structure Type: built works - dwellings - houses - apartment houses

Designers: D’Amato Conversano, Incorporated, (DCI) Engineers (firm); SkipStone Development (firm); Swinerton Builders, Building Contractors (firm); TimberLab (firm); atelierjones LLC (firm); Susan Hannen Jones (architect)

Dates: constructed 2022-2023

8 stories, total floor area: 67,000 sq. ft.

1323 East Union Street
First Hill, Seattle, WA 98122

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This 8-floor, mass-timber apartment tower was the first erected in Seattle utilizing new wood-framing technologies that were intended to make high-density buildings more sustainable. As noted in the Seattle Times on 03/30/2023: "It has an entire superstructure of mass timber, with the exception of the lateral bracing — seismic bracing — which is steel, and a very modest concrete foundation because of the lightness of wood coming down on this eight-story building." (See Amanda Kolson Hurley, Seattle, "How a Seattle architect helped make timber towers legal in the U.S.," published 03/30/2023, accessed 03/30/2023.)

Building History

In 2022-2023, Heartwood became the first mass-timber highrise apartment building in the United States, standing 8 stories tall and containing 67,000 square feet and 126 middle-income level units. It was financed almost completely with private money, most furnished by the non-profit group Community Roots Housing. This private money was supplemented by a $250,000 United States Forest Service (USFS) grant from the United States Department of Agriculture (USDA) received in 2019.

A 2020 building in Spokane, by the Menlo Park, CA,-based developer, Kanterra, utilized Cross-laminated Timber (CLT) structural members for its new five-story, 150,000-square-foot building, Catalyst, erected for Eastern Washington University (EWU). Building higher than six floors was previously beyond code regulations for wood-framed structures, but the strength of CLT panels made this limitation unneccessary. CLT structural members had been used in Europe for many years before being tested in the US.

In 03/2023, the website said of the project: "The eight-story project will be the first Type IV-C [International Building Code} IBC Building Code building permitted in the City of Seattle and the first in the US under construction. The Mass Timber/Hybrid superstructure consists of exposed CLT ceilings and Glulam column and beams within the units, hallways and lobby. Exposed MPP exit stairs are utilized, as part of the steel lateral core. The 8-story, centrally located building provides 126 units of workforce housing alongside an outdoor courtyard, bike parking, retail, laundry. The project broke ground in April 2022 and is currently under construction." (See, "Heartwood," accessed 03/30/2023.) The project was projected to be completed in 07/2023.

PCAD id: 24625