The long-running plan to replace the Alki Lumber site in the West Seattle Triangle is finally shifting from talk to actual paperwork that leads to construction. New city filings show demolition and excavation permits could be close, with the east block through major approvals and the west block reported to be in the last stretch of technical review. If the current timeline sticks, crews could be fencing and mobilizing the site in spring 2026.
What the project will deliver
Together, the two Sweeney Blocks are expected to bring roughly 300 apartments, around 10,000 to 12,000 square feet of ground-floor retail, and more than 150 underground parking stalls, turning a decades-old lumberyard into a mixed-use gateway at the edge of the Triangle.
The detailed breakdown comes from city permit documents. The design packet filed with the city lists about 284 units and roughly 10,500 square feet of retail for the east block, according to SDCI. Combined with the companion building, those figures line up with the overall unit and retail totals now attached to the project.
Where approvals stand
The eastern building at 4406 36th Ave SW has already cleared the Southwest Design Review Board and later secured full land use approval. Across the site, the Fauntleroy-facing west block is still working its way through technical review with city planners.
West Seattle Blog tracked the east block through design review, documenting how the plans shifted in response to neighborhood feedback. Early outreach published by the city names HB Management and the Sweeney family as the project applicants and centers the parcels around the future Avalon station as the focus of the redevelopment, according to City of Seattle materials.
What’s next
Project filings show engineers have already submitted stormwater, shoring, and excavation plans, and the applicant is expected to seek a final land use decision for the west building in the near term. Demolition permits and site mobilization are currently projected for spring 2026, with demolition and excavation penciled in for summer if the schedule holds, according to Westside Seattle.
Tiscareno Associates, the architect of record on the east block working alongside Ankrom Moisan, says the design leans into wood-inspired materials and wider sidewalks as a nod to the site’s lumberyard history, according to project materials. In other words, the new buildings are designed to remember what stood there before they arrived.
Why this matters for the Triangle
The Sweeney Blocks are set to add hundreds of homes and new retail to a corridor that is already lined up for major transit upgrades. Planners say the project is meant to stitch new public space into the existing street network, rather than just dropping two big buildings on the map.
A public-realm brief by Northwest Studio notes that the parcels sit right next to Sound Transit’s future Avalon station and calls for wider boardwalks and other pedestrian amenities to bring more life to the sidewalks, according to Northwest Studio. For nearby residents, that likely means a very different Fauntleroy and Avalon corridor over the next several years as the Triangle fills in with new shops, services, and people.
Developers and the Sweeney family have long framed the project as a planned evolution of the Triangle. At this point, the big milestones depend on the city’s final signoffs and the absence of any appeals. We will keep an eye on permit postings and city filings as the Sweeney Blocks move from paper to pavement.
