1100 9th Ave, Seattle, WA 98101

Office · Seattle · Seattle-Bellevue metro, WA

Imagery suggests: medical office, 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 AI estimate from public imagery; may be outdated.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 957 reachable office buildings in Seattle. Larger than 79% of office buildings in Seattle (median 20,410 SF), derived from assessor records.

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Building size: 126,958 SF, King County Assessor
Lot size: 15,360 SF, King County Assessor
Year built: 1975, King County Assessor
Stories: 8, King County Assessor
Predominant use: Mason Clinic- Buck Pavilion, King County Assessor
Assessed value: $30,912,000, per the King County Assessor (not a market appraisal)
Assessed value per building SF: $243.48/SF, derived from assessor records
Lot coverage: 827%, derived from assessor records
Vintage: 1970s vintage
Zoning: MIO-240-HR (M), King County
County use code: Office Building
Construction (observed): masonry, AI estimate from public imagery
Parking (observed): street only, AI estimate from public imagery
Frontage (observed): mid block, AI estimate from public imagery

Nearby comparable buildings

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

901 Seneca St, Seattle · 0 mi · 76,968 SF · built 1952 · assessed $123.11/SF
909 University St, Seattle · 0.1 mi · 310,689 SF · built 1988 · assessed $185.26/SF
1201 9th Ave, Seattle · 0.1 mi · 206,950 SF · built 1999 · assessed $515.26/SF
1000 Seneca St, Seattle · 0.1 mi · 25,416 SF · built 1946 · assessed $408.93/SF
1218 Terry Ave, Seattle · 0.1 mi · 48,700 SF · built 1925 · assessed $289.28/SF
921 Terry Ave, Seattle · 0.1 mi · 121,099 SF · built 1983 · assessed $306.99/SF

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Sale history and market context

MakeMe Estimate: $31,223,282 (estimated market value), with a likely range of $28,218,107 to $40,682,458 (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.

2026-02-25: $155,000 from Private party to Private party (part of a 12-parcel sale; price is the whole deal), rec. 20260227000360

1994-06-01: transfer from Private party to Virginia Mason Medical Center (part of a 4-parcel sale; price is the whole deal), rec. 199407290557

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 $18,848,000 (2011) to $30,912,000 (2026), up 64% over 15 years, per county tax rolls. The 2026 roll splits $30,912,000 into $8,832,000 land and $22,080,000 improvements.

Zoning: MIO-240-HR (M) (per King County)

Lot: 15,360 sq ft

Water: Water District (per King County)

Sewer: Public (per King County)

Access: Public

Street surface: Paved

Floor and use mix: Medical Office 111,668 SF; Basement, Finished 15,290 SF (county building sections)

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

Permit history

2022-03-16: Remodel, declared value $1,200,000 (Screened), permit 6849716-CN

2021-11-30: Remodel, declared value $446,744 (Screened), permit 6832698-CN

2020-12-30: Remodel, declared value $150,000 (Screened), permit 6789636-CN

2015-07-15: Remodel, declared value $336,036 (Screened), permit 6443713

2014-07-18: Remodel, declared value $2,100,000 (Screened), permit 6397835

2014-07-03: Remodel, declared value $258,339 (Screened), permit 6379584

2014-06-28: Remodel, declared value $6,978,313 (Screened), permit 6391462

2014-05-17: Remodel, declared value $812,998 (Screened), permit 6391339

2013-12-28: Remodel, declared value $10,730,000 (Complete), permit 6380088

2013-12-17: Remodel, declared value $950,000 (Screened), permit 6393271

Source: King County permit records (newest first).