What PlatNum reads
Every PlatNum result is assembled from public records, published code, official GIS services, and dated market evidence. This page names each one, who publishes it, how often it refreshes, and what it cannot tell you.
Who owns the land and what may be built
Whatcom County
Parcel boundaries, parcel identifiers, owner of record, assessed land and improvement values, recorded transfers, subdivisions, and recorded lots.
Whatcom County
Zoning designations and planning overlays for unincorporated county parcels.
Bellingham, Blaine, Everson, Ferndale, Lynden, Nooksack, and Sumas
City zoning districts. Where a city publishes no current machine-readable service, the adopted zoning map is used as the authority instead.
Each jurisdiction
Use tables, dimensional standards, density, parking, and open-space rules, translated into structured rules that retain their citation and effective date.
What limits the buildable area
Whatcom County and cities, with upstream content from FEMA, USGS, and Washington Department of Ecology
Wetland, stream, shoreline, flood, geohazard, and habitat screens, plus the buffers that reduce a buildable envelope.
OpenStreetMap contributors, Overture Maps Foundation, Microsoft, and Whatcom County
Existing structures on a parcel, used to model retained buildings and available site area.
Where no qualified footprint exists, the app draws an approximation from assessor records and labels it "approximate footprint". An approximation is never presented as source geometry.
OpenStreetMap copyrightWhatcom County
Road classification used to resolve front setbacks per edge.
Where reliable road classification is unavailable, front setbacks fall back to a Minor Access Street assumption.
What the market and the permit counter show
City of Bellingham
Project-level permit records used for development activity and nearby-permit evidence.
Project-level permit detail is Bellingham only. No other jurisdiction in the county publishes an equivalent feed today.
US Census Bureau
Per-jurisdiction residential permit counts and valuation, countywide.
These are lagging aggregate totals, not individual permit records.
RentCast
Active for-sale listings and rental comparables, captured as dated snapshots.
These are dated snapshots, not live MLS data. A property missing from a snapshot is not evidence that it is off market.
PlatNum, from dated public evidence
Cap rates, rents, sale rates, and marketability assumptions that feed the valuation line, each versioned with its evidence, period, and confidence label.
Assumptions are modeled inputs, not observed transactions. Overrides you enter are labeled separately from published benchmarks.
OpenStreetMap contributors, via Nominatim
A fallback address lookup when county exact-address search does not resolve.
Required notices
Publishers of the data behind PlatNum require these notices.
Data provided by permission of Whatcom County
Whatcom County grants a limited, revocable right to use and reproduce County data and requires this legend. The County disclaims accuracy and makes no warranty about third-party material contained in its layers.
© OpenStreetMap contributors, Overture Maps Foundation
Building footprint and geocoding data derived from OpenStreetMap, Overture, and Microsoft building datasets is licensed under the Open Database License 1.0.
© CARTO, © OpenStreetMap contributors, Imagery © Esri, Maxar, Earthstar Geographics
Basemap tiles are supplied by their respective providers and carry their own terms. Tile attribution is separate from attribution for the parcel, zoning, and footprint data drawn on top of them.
Building Permits Survey, US Census Bureau
Census permit totals are public domain works of the United States government, used here as lagging jurisdiction-level activity signal.
Honest boundaries
A zoning designation, a mapped buffer, or a permit record describes what a public agency has published. None of them is a permit determination, a use approval, or a guarantee that a jurisdiction will agree with the analysis.
PlatNum keeps four distinct dates per result — when the fact applied, when it was collected, when it became active, and when the analysis ran. A saved report holds the values available when it was created; later amendments can stale it.
Bellingham has the deepest rule and permit coverage. Smaller jurisdictions rely on adopted maps and published code without a current machine-readable service, so results there lean more heavily on structured code rules than on GIS.
Where a publisher grants access for analysis but not redistribution, PlatNum uses the data to compute a result without republishing the underlying records or geometry. That is why some evidence appears as a cited conclusion rather than a downloadable layer.
Continue
Methodology covers coverage, freshness semantics, and how to read a result.