20313 28th Ave S, Seatac, WA 98198

Office · Seatac · Seattle-Bellevue metro, WA

One of 37 reachable office buildings in Seatac. Larger than 92% of office buildings in Seatac (median 14,270 SF), derived from assessor records.

Usable building area
79,636 SF, King County Assessor
County gross area
91,636 SF, King County Assessor
Excluded area
12,000 SF outside primary usable area
Lot size
181,957 SF, King County Assessor
Year built
1980, King County Assessor
Stories
3, King County Assessor
Predominant use
Office & Storage, King County Assessor
Assessed value
$14,283,300, per the King County Assessor (not a market appraisal)
Assessed value per usable SF
$179.36/SF, derived from assessor records
Usable area / lot
0.44, derived from assessor records
Vintage
1980s vintage
Zoning
RBX, King County
County use code
Office Building

Nearby comparable buildings

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

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Sale history and market context

MakeMe Estimate: $17M (estimated market value), with a likely range of $15M to $19.7M (half of recent verified sales in this segment landed inside that range). Based on 7 verified arm's-length comparable sales (through 2026-06-01). Not an appraisal. How this estimate works.

lower confidence: 0 comparable sales within 3 miles; nearest 3.5 mi. This property type carries wider measured error; treat the estimate as a starting point.

Comparable sales used as evidence

Recorded arm's-length sales of similar buildings nearby; nearer and more recent sales rank first. Buyer and seller names are withheld. Get this data via API.

Last sold: 1984-01-04 for $1,580,000 (recorded arm's-length sale).

Current ownership dates to 1984 (about 42 years) per recorded transfers.

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

Value over time

$0$10M$20M$30M201120142017202020232026$17M$14.3MCounty assessed valueMakeMe Estimate range

Dark line: county assessed value per King County tax rolls. Blue line: our estimate; dashed years are a modeled backcast built from recorded arm's-length sales in the building's segment, not estimates published at the time, and years without enough sales stay unmodeled. The shaded range is the model's measured error band; about half of verified sales in the segment land inside it. Diamonds: recorded arm's-length sales. Not an appraisal. How this estimate works.

Land, site, and value history

Assessed value moved from $11,387,900 (2011) to $14,283,300 (2026), up 25% over 15 years, per county tax rolls. The 2026 roll splits $14,283,300 into $6,368,400 land and $7,914,900 improvements.

Taxes

Permit history

Source: King County permit records (newest first).