307 Westlake Ave N, Seattle, WA 98109

Office · Seattle · Seattle-Bellevue metro, WA

One of 957 reachable office buildings in Seattle. Larger than 81% of office buildings in Seattle (median 20,410 SF), derived from assessor records.

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Building size: 162,200 SF, King County Assessor
Lot size: 25,920 SF, King County Assessor
Year built: 2003, King County Assessor
Stories: 5, King County Assessor
Predominant use: Office/Lab Bldg., King County Assessor
Assessed value: $73,165,300, per the King County Assessor (not a market appraisal)
Assessed value per building SF: $451.08/SF, derived from assessor records
Lot coverage: 626%, derived from assessor records
Vintage: 2000s vintage
Zoning: SM-SLU 175/85-280, King County
County use code: Medical/Dental Office

Nearby comparable buildings

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

320 Westlake Ave N, Seattle · 0 mi · 303,103 SF · built 2006 · assessed $247.82/SF
903 Thomas St, Seattle · 0 mi · 254,218 SF · built 2018 · assessed $202.92/SF
325 9th Ave N, Seattle · 0.1 mi · 480,702 SF · built 2014 · assessed $229.12/SF
224 Westlake Ave N, Seattle · 0.1 mi · 36,513 SF · built 1926 · assessed $294.42/SF
321 Terry Ave N, Seattle · 0.1 mi · 209,816 SF · built 2006 · assessed $259.18/SF
225 Terry Ave N, Seattle · 0.1 mi · 69,040 SF · built 2007 · assessed $164.50/SF

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Sale history and market context

MakeMe Estimate: $71,063,550 (estimated market value), with a likely range of $64,223,835 to $92,592,443 (half of recent verified sales in this segment landed inside that range). Based on 55 verified arm's-length comparable sales (through 2026-05-29). Not an appraisal. How this estimate works.

Last sold: 2015-02-11 for $89,696,000 (recorded arm's-length sale).

Current ownership dates to 2015 (about 11 years) per recorded transfers.

2015-02-11: $89,696,000 from 307 Westlake LLC to BMR Westlake LLC, rec. 20150211000322

2002-12-19: $1,017,227 from City Investors VI LLC to 307 Westlake LLC, rec. 20021223000927

1996-06-19: transfer from Private party to City Investors VI LLC /Vulcan NW INC (non-market transfer), rec. 199606201600

1993-05-21: $1,000,000 from Pine Corporation &Goodfellow J to Private party (non-market transfer), rec. 199305211666

1993-05-21: $350,000 from Private party to Private party (part of a 10-parcel sale; price is the whole deal), rec. 199305240000

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 $25,368,900 (2011) to $73,165,300 (2026), up 188% over 15 years, per county tax rolls. The 2026 roll splits $73,165,300 into $18,024,700 land and $55,140,600 improvements.

Zoning: SM-SLU 175/85-280 (per King County)

Lot: 25,920 sq ft

Water: Water District (per King County)

Sewer: Public (per King County)

Access: Public

Street surface: Paved

Floor and use mix: Laboratories 59,975 SF; Office Building 48,339 SF; Basement, Parking 42,567 SF; Retail Store 8,819 SF (county building sections)

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

Permit history

2020-12-02: Remodel, declared value $339,400 (Complete), permit 6812910-CN

2019-01-23: Remodel, declared value $60,000 (Screened), permit 6709488-CN

2019-01-04: Remodel, declared value $50,000 (Screened), permit 6706412-CN

2017-09-25: Remodel, declared value $502,000 (Complete), permit 6596328

2017-02-24: Remodel, declared value $83,000 (Complete), permit 6565442

2016-08-08: Remodel, declared value $81,335 (Complete), permit 6518970

2014-11-06: Remodel, declared value $90,306 (Complete), permit 6440069

2013-08-23: Remodel, declared value $150,000 (Complete), permit 6373058

2011-08-19: Remodel, declared value $200,000 (Complete), permit 6283205

2005-08-31: Remodel, declared value $250,000 (Complete), permit 752661

Source: King County permit records (newest first).