Parametric Search

Filter by Neighborhood

Show Me Lots That Fit

Map Layers

Buildable Envelopes

Pre-calculated development capacity

Environmental Constraints

Steep slopes, landslide areas

ECA Conflict Lots

Highlight lots with ECA overlap

CSO Basin Overlay

Combined sewer overflow basin boundaries

CSO Basin Lots

Highlight lots inside CSO basins

Capacity Constrained

Highlight lots in constrained drainage areas

Zoom to z14+ to see buildable envelopes glow on individual lots. Click any parcel for development details.

Urban Acupuncture

Seattle's Middle Housing Tool

The One Seattle Plan (January 2026) changed the rules for every Seattle homeowner. What can your lot do? Find out how many homes you can build, what they'll cost, and what you can earn.

🏘️100K+Seattle lots affected

🏗️4–6 unitsAllowable on each

💵Rent or sellYour choice

enter your address to start

Free & open source · Seattle parcels only