Another 45-Story Tower Gets Green Light for South Lake Union Skyline

A 45-story residential tower is set to break ground in South Lake Union this fall after developer Pinnacle Properties secured its final building permit from the Seattle Department of Construction & Inspections late last week. The project, named The Cascade Spire, will add 450 new apartments to the corner of Boren Avenue and John Street, placing it squarely in the heart of Amazon’s urban campus.

This approval lands as Seattle grapples with a persistent housing affordability crisis and mixed signals about the future of downtown. While other American cities see Fourth of July fireworks canceled by extreme heat, Seattle's development pipeline is firing on all cylinders. The Cascade Spire represents a multi-hundred-million-dollar bet that the demand for high-end, centrally located housing will continue to outstrip supply, despite ongoing debates about remote work and the vitality of the city core.

A Vertical Bet on the Denny Triangle

The tower will replace a single-story commercial building and a surface parking lot, a familiar pattern of transformation in the Denny Triangle neighborhood. Its location is strategic, situated just two blocks from the Denny Way corridor and within easy walking distance of thousands of tech jobs, Whole Foods, and the Westlake transit hub. Pinnacle’s plan, filed under SDCI project number 3039811-LU, calls for a mix of studio, one-, and two-bedroom units, along with nearly 8,000 square feet of ground-floor retail space.

Unlike the low-slung developments that characterize neighborhoods like Ballard or Capitol Hill, The Cascade Spire follows the city’s urban-village strategy of concentrating extreme density near major employment centers. The project will contribute to the city’s Mandatory Housing Affordability (MHA) program, with Pinnacle opting to pay an estimated $12 million fee-in-lieu rather than designate units onsite as affordable. That money will be directed to the Seattle Office of Housing to fund affordable housing construction elsewhere in the city.

Rent Relief or Luxury Glut?

The critical question for renters is what 450 new units will do to prices. According to data from CoStar Group, the average asking rent for a new one-bedroom apartment in the 98109 zip code hit $2,910 in the second quarter of 2026. Citywide vacancy rates have ticked up slightly to 6.2%, a healthier figure than the sub-4% rates of the last decade, but one that has failed to bring significant, lasting price relief for tenants. The sheer volume of high-end apartments coming online has created a sub-market of its own, often featuring months of free rent as initial lease-up incentives.

Pinnacle aims to complete construction by the third quarter of 2028. For now, the most immediate impact will be felt by commuters navigating the already congested streets around Denny Park. Once ground is broken in October, residents can expect at least two years of lane closures, concrete pours, and construction noise. Whether the tower’s completion in 2028 will be met by a market hungry for more luxury units or one saturated by them is the gamble developers across the city are now taking.