521 S Monroe St, Seattle, WA 98108

Small-Bay Industrial · Seattle · Seattle-Bellevue metro, WA

One of 2,011 reachable small-bay industrial buildings in Seattle. Larger than 57% of small-bay industrial buildings in Seattle (median 10,000 SF), derived from assessor records.

Usable building area
11,970 SF, King County Assessor
Lot size
17,500 SF, King County Assessor
Year built
1979, King County Assessor
Stories
1, King County Assessor
Predominant use
Warehouse, King County Assessor
Assessed value
$2,360,200, per the King County Assessor (not a market appraisal)
Assessed value per usable SF
$197.18/SF, derived from assessor records
Usable area / lot
0.68, derived from assessor records
Vintage
1970s vintage
Zoning
MML U/85, King County
County use code
Warehouse

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: $3.3M (estimated market value), with a likely range of $2.7M to $3.73M (half of recent verified sales in this segment landed inside that range). Based on 8 verified arm's-length comparable sales (through 2026-06-01). Not an appraisal. How this estimate works.

moderate confidence: 5 comparable sales within 3 miles; nearest 1.4 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.

Market context: Industrial in Seattle

median verified sale $313.30/SF over the trailing 24 months; 40 sales in the last 12 months and 81 in 24 (newest verified sale 2026-05); the middle 80% of recent sales traded at 0.66x to 1.59x their county assessed value, median 1.06x (80 sales with usable county values).

  • 2022: $360.01/SF median (39 sales)
  • 2023: $354.62/SF median (33 sales)
  • 2024: $329.79/SF median (32 sales)
  • 2025: $289.77/SF median (46 sales)
  • 2026 YTD: $307.69/SF median (11 sales)

This estimate sits at 1.40x county assessed value, the 79th percentile of those recent sale premiums.

Computed from 1,501 verified arm's-length sales in King County public records (81 in the trailing 24 months). Free public records. Not an appraisal.

Ownership tenure is not asserted for this parcel: the most recent recorded transfer is a non-market conveyance.

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

Value over time

$0$1M$2M$3M$4M201120142017202020232026$3.3M$2.36MCounty 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 $864,000 (2011) to $2,360,200 (2026), up 173% over 15 years, per county tax rolls. The 2026 roll splits $2,360,200 into $1,006,200 land and $1,354,000 improvements.

Taxes