301 S 320th St, Federal Way, WA 98003

Office · Federal Way · Seattle-Bellevue metro, WA

One of 189 reachable office buildings in Federal Way. Larger than 88% of office buildings in Federal Way (median 9,780 SF), derived from assessor records.

Usable building area
53,974 SF, King County Assessor
County gross area
60,210 SF, King County Assessor
Excluded area
6,236 SF outside primary usable area
Lot size
584,659 SF, King County Assessor
Year built
1974, King County Assessor
Stories
1, King County Assessor
Predominant use
Medical Clinic, King County Assessor
Assessed value
$14,613,500, per the King County Assessor (not a market appraisal)
Assessed value per usable SF
$270.75/SF, derived from assessor records
Usable area / lot
0.09, derived from assessor records
Vintage
1970s vintage
Zoning
OP, King County
County use code
Medical/Dental Office

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: $14.1M (estimated market value), with a likely range of $12.4M to $18.1M (half of recent verified sales in this segment landed inside that range). Based on 5 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 4.8 mi. This property type carries wider measured error; treat the estimate as a starting point. Comparable-sale caveat: the estimate is 50% above the $173.25/SF median of the shown comparable sales.

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.

Market context: Office in Federal Way

median verified sale $245.41/SF over the trailing 24 months; 2 sales in the last 12 months and 5 in 24 (newest verified sale 2026-03).

  • 2022: $234.46/SF median (6 sales)
  • 2023: $210.86/SF median (4 sales)
  • 2024: $369/SF median (6 sales)

Computed from 218 verified arm's-length sales in King County public records (5 in the trailing 24 months). Free public records. Not an appraisal.

Value over time

$0$10M$20M$30M201120142017202020232026$14.1M$14.6MCounty 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. Not an appraisal. How this estimate works.

Land, site, and value history

Assessed value moved from $7,893,700 (2011) to $14,613,500 (2026), up 85% over 15 years, per county tax rolls. The 2026 roll splits $14,613,500 into $5,206,500 land and $9,407,000 improvements.

Taxes

Permit history

Source: King County permit records (newest first).