Building Fundamentals
Union SLU was built in 2013 and holds 284 units across 214,123 square feet of net rentable area, an average of about 754 square feet per unit, according to Yardi Matrix, a commercial real-estate data provider that tracks building-level records independently of leasing sites. Unit sizes on the current floor plan menu run from 506 to 1,069 square feet, studio through two-bedroom, per ApartmentGuide’s listing.
Two listing sites disagree on the building’s height. Apartment Finder states six stories. RentCafe states seven. Neither cites a source for the figure, and no public record was findable to settle it, so the honest answer is that the story count is unconfirmed.
| Metric | Value | Source |
|---|---|---|
| Address | 905 Dexter Ave N, Seattle, WA 98109 | Multiple listing sites |
| Year built | 2013 | Yardi Matrix |
| Total units | 284 | Yardi Matrix |
| Total building area | 214,123 sq ft | Yardi Matrix |
| Unit size range | 506–1,069 sq ft | ApartmentGuide |
How old is the building and how large is it? Built in 2013, 284 units, 214,123 total square feet per Yardi Matrix. The number of floors is disputed between listing sites (six versus seven) and unconfirmed from a public record.
What Union SLU’s Rent Costs
The clearest single price point comes from Zumper’s studio-through-three-bedroom median table, dated March 7, 2026: studios at $1,619, one-bedrooms at $2,141, two-bedrooms at $2,950. One specific advertised floor plan, the Donzi Studio, was listed on ApartmentGuide at $1,867 to $2,082 for 506 square feet, working out to roughly $3.69 to $4.12 per square foot: a floor-plan-level anchor, not a building average.
Apartments.com lists required monthly fees of $16 to $50 depending on the unit, on top of base rent. That figure, not the headline “starting at” number every listing site leads with, is what actually determines total monthly cost.
| Fee | Typical range | What it covers |
|---|---|---|
| Required monthly fee (varies by unit) | $16 to $50 per month | Community-wide services, per the posted fee schedule |
| Move-in nonrefundable fee (city-wide cap) | Up to 10% of first month’s rent | Cleaning and screening only, under Seattle law |
| Pet deposit (city-wide cap) | Up to 25% of first month’s rent | Pet-related damage |
Is the quoted starting rent the total monthly cost? No. Add the required monthly fee, $16 to $50 at Union SLU depending on unit, before comparing the number to a competing building’s quote.
How Union SLU Compares in South Lake Union
Three other South Lake Union buildings show up in the same searches: Ascent SLU (1145 Republican St), Kiara (111 Terry Ave N), and Shoresmith (1170 Republican St). Ascent, built in 2018 by Greystar, opened with rents ranging from $2,476 to $9,280 according to Seattle’s Daily Journal of Commerce. The building’s most visible design signature is an illuminated “Z fin” running up its north facade, and the property holds 340 parking stalls.
| Building | Built | Units | Starting rent | Sq ft range | Approx. $/sq ft (matched unit) |
|---|---|---|---|---|---|
| Union SLU | 2013 | 284 | $1,619 (studio, Mar 2026) | 506–1,069 | $3.69–$4.12 (506 sq ft studio) |
| Ascent SLU | 2018 | 251 | $2,953+ (1BR) | 631–1,831 | $4.81–$4.83 (725 sq ft 1BR) |
| Kiara | 2018 | 460 | $2,255+ (studio) | 474–2,592 | $5.18 (987 sq ft 2BR) |
| Shoresmith | 2021 | 113 | $1,925+ (studio) | 383–779 | ~$4.70–$5.03 (estimated from smallest studios) |
Union SLU’s per-square-foot number is the lowest of the four. It’s also the oldest building in the set by five years over the next-oldest.
How does Union SLU’s price per square foot compare to nearby South Lake Union buildings? Roughly $3.69 to $4.12 at Union SLU versus $4.81 and up at Ascent SLU and Kiara, based on one matched floor plan at each building rather than a building-wide average.
Seattle and Washington Rules That Apply Here
Seattle caps what any landlord in the city can collect at move-in: a security deposit plus nonrefundable fees can’t exceed one month’s rent, the nonrefundable portion is capped at 10% of that month’s rent, and a pet deposit tops out at 25%, per the city’s official move-in cost page. Tenants can split those costs into installments, up to six payments on a lease of six months or longer.
The more consequential rule for comparing these four buildings is Washington’s HB 1217, the statewide rent-stabilization law: no increase in a tenancy’s first 12 months, and after that, increases capped at the lower of 7% plus the local Consumer Price Index or 10%, which the Washington Department of Commerce set at 9.683% for calendar year 2026. New construction is exempt from that percentage cap for its first 12 years, per the Washington State Standard‘s reporting on the law. Union SLU, built in 2013, crossed the 12-year mark in 2025 and is now inside the cap’s reach. Ascent SLU and Kiara, both completed in 2018, stay exempt until 2030. Shoresmith, completed in 2021, stays exempt until 2033.
Seattle separately requires 180 days’ written notice before any rent increase, longer than the state’s 90-day floor, per the city’s Rental Agreement Regulation page, and requires a valid legal reason to end a tenancy under the Just Cause Eviction Ordinance.
What Seattle-specific rules apply when leasing here? A 180-day notice requirement for any rent increase, move-in costs capped at one month’s rent combined, and a 12-year exemption from the state rent cap that Union SLU has now aged out of while its three newer neighbors have not.
What Isn’t Public Yet
None of the four buildings’ listing pages disclose how many of their units are studios versus one- or two-bedrooms. Yardi Matrix would have that breakdown, but it sits behind a paid data request. Treat any building’s “studio through two-bedroom” range as a menu of what’s offered, not a count of how much of each type exists.
What Residents Say
Review platforms aggregate resident sentiment for all four buildings, but the summaries are synthesized, unattributed praise with no disclosed reviewer count or date range. Treat lines like “residents appreciate the modern finishes” as marketing-adjacent color rather than evidence, unless a specific review is individually dated and attributed to a named platform.
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