400 E Union St, Seattle, WA 98122

Multifamily · Seattle · Seattle-Bellevue metro, WA

Imagery suggests: modern multifamily, appears multi-tenant. AI estimate from public imagery. In recent public imagery (2026-06), the building appears well maintained. AI estimate from public imagery; may be outdated.

One of 5,391 reachable multifamily buildings in Seattle. Larger than 49% of multifamily buildings in Seattle (median 9,444 SF), derived from assessor records.

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Building size: 9,154 SF, King County Assessor
Lot size: 5,362 SF, King County Assessor
Year built: 1962, King County Assessor
Stories: 3, King County Assessor
Predominant use: Union Plaza, King County Assessor
Units: 20, King County Assessor
Assessed value: $3,746,000, per the King County Assessor (not a market appraisal)
Assessed value per building SF: $409.22/SF, derived from assessor records
Lot coverage: 171%, derived from assessor records
Vintage: 1960s vintage
Zoning: MR (M), King County
County use code: Apartment
Parking (observed): structured, AI estimate from public imagery

Nearby comparable buildings

Same building type, by distance. Assessor facts only; not an opinion of value.

1411 Bellevue Ave, Seattle · 0 mi · 12,280 SF · built 1909 · assessed $383.64/SF
1323 Minor Ave, Seattle · 0 mi · 94,400 SF · built 1991 · assessed $162.80/SF
1400 Boren Ave, Seattle · 0.1 mi · 63,681 SF · built 1925 · assessed $226.21/SF
1412 Summit Ave, Seattle · 0.1 mi · 23,600 SF · built 1908 · assessed $369.03/SF
1420 Boren Ave, Seattle · 0.1 mi · 21,712 SF · built 1925 · assessed $279.75/SF
1330 Boren Ave, Seattle · 0.1 mi · 57,930 SF · built 1925 · assessed $234.23/SF

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Sale history and market context

MakeMe Estimate: $3,613,005 (estimated market value), with a likely range of $3,207,219 to $4,121,434 (half of recent verified sales in this segment landed inside that range). Based on 667 verified arm's-length comparable sales (through 2026-05-29). Not an appraisal. How this estimate works. About $181K per unit at the midpoint (20 units).

Current ownership dates to 2020 (about 6 years) per recorded transfers.

3 administrative transfers (no consideration), 2001 to 2020

1999-12-01: $137,553 from Private party to Private party (non-market transfer), rec. 19991210001825

1999-12-01: transfer from P & D Lettenmaier Partnership to Private party (non-market transfer), rec. 19991210001824

Source: King County recorded sales extract; buyer and seller shown only when a company or organization. Individual names are withheld.

Value over time

Solid line: county appraised value per King County tax rolls. Shaded range: our modeled estimate for each year, built from recorded arm's-length sales in the building's segment; years without enough sales stay unmodeled. Dots: recorded arm's-length sales. Not an appraisal. How this estimate works.

Land, site, and value history

Assessed value moved from $1,300,000 (2011) to $3,746,000 (2026), up 188% over 15 years, per county tax rolls. The 2026 roll splits $3,746,000 into $2,144,800 land and $1,601,200 improvements.

Zoning: MR (M) (per King County)

Lot: 5,362 sq ft

Water: Water District (per King County)

Sewer: Public (per King County)

Access: Public

Street surface: Paved

Floor and use mix: Multiple Residence (Low Rise) 9,154 SF (county building sections)

County districts report (schools, fire, sewer, council; on kingcounty.gov)