Seattle building & ADU permits
Recent permit activity, updated continuously.
Seattle anchors Washington's Puget Sound housing market, where HB 1337 now requires cities to allow at least two ADUs per lot and HB 1110 phases out single-family-only zoning. The city's public-domain open-data portal is license-free, so Igni can surface new Seattle residential and ADU permits with sub-24-hour freshness.
Igni is tracking 1,365 residential and building permits in Seattle, WA — including 383 classified accessory-dwelling-unit (ADU) filings. The most active ZIP is 98115. The most recent filing Igni tracked was Sep 17, 2026. All records come from data.seattle.gov (Socrata), an official government open-data feed, and are refreshed continuously.
1365
Permits tracked
383
ADU permits
24
Distinct ZIP codes
Sep 17, 2026
Newest permit
Recent permits
A sample of the freshest permits in this jurisdiction — ZIP and city only (no street addresses).
| ZIP | Permit type | ADU type | Valuation | Applied |
|---|---|---|---|---|
| 98178 | Residential | Detached ADU | $193,796 | Dec 4, 2025 |
| 98103 | Residential | — | $273,116 | Apr 1, 2026 |
| 98103 | Residential | — | $284,270 | Apr 1, 2026 |
| 98178 | Residential | Detached ADU | $338,158 | Dec 9, 2025 |
| 98178 | Residential | — | $149,777 | Apr 23, 2026 |
| 98136 | Residential | — | $442,716 | Feb 18, 2026 |
| 98115 | Residential | — | $740,746 | Jul 20, 2026 |
| 98136 | Residential | — | $429,757 | Feb 18, 2026 |
| 98136 | Residential | — | $429,757 | Feb 18, 2026 |
| 98103 | Residential | — | $282,764 | Apr 16, 2026 |
| 98136 | Residential | — | $442,716 | Feb 18, 2026 |
| 98103 | Residential | — | $302,504 | Apr 16, 2026 |
| 98115 | Residential | — | $315,822 | Aug 3, 2026 |
| 98146 | Residential | — | $307,937 | Apr 22, 2026 |
| 98106 | Residential | Attached ADU | $453,900 | Jun 26, 2025 |
| 98106 | Residential | Attached ADU | $287,314 | Jun 26, 2025 |
| 98115 | Residential | — | $500,976 | Dec 3, 2025 |
| 98146 | Residential | — | $307,937 | Apr 22, 2026 |
| 98109 | Commercial | — | $70,000 | Aug 10, 2026 |
| 98103 | Residential | — | $617,487 | Dec 16, 2025 |
Top ZIP codes by recent activity
ADU types in the recent set
Housing law — Washington
Washington's HB 1337 (2023) requires cities to allow at least two ADUs per lot in urban growth areas, bans owner-occupancy requirements, and limits parking and impact fees.
HB 1110 (2023) ends single-family-only zoning in larger cities, requiring duplex-to-sixplex middle housing scaled by city size, with Puget Sound cities phasing in compliance from 2025.
Seattle ADU rules
Seattle permits two accessory dwelling units on most residential lots — an attached ADU (AADU), which includes a basement or converted-garage apartment, plus a detached ADU (DADU), the classic 'backyard cottage'; a 2025 update also lets owners build two DADUs on a single lot. The city removed its owner-occupancy requirement in 2019, so both the main house and the ADU(s) may be rented.
Detached units are generally capped around 1,000 square feet of above-grade floor area, and Seattle requires no off-street parking for an ADU anywhere in the city — both standards are more generous than Washington's statewide floor. In the city's Neighborhood Residential zones a detached cottage can rise to roughly 32 feet, and an ADU's height and setbacks are generally no more restrictive than those for the primary home. A standard, code-compliant ADU is reviewed administratively through the building permit, without a design-review hearing.
To speed that process, Seattle runs a pre-approved DADU program through its ADUniverse plan gallery, offering a set of staff-reviewed detached-cottage designs that can substantially cut permitting time in the city's Neighborhood Residential zones. The current rules were consolidated in 2025 (Seattle Municipal Code 23.42.022) to comply with Washington's HB 1337 ADU law and HB 1110 middle-housing law, building on Seattle's original 2019 'backyard cottage' ordinance.
This is an informational summary — verify current rules with the city's planning/permitting department; not legal advice.
See also: Washington ADU law and what is an ADU?
Data source
Sourced from data.seattle.gov (Socrata). Public Domain.
Nearby cities — Washington
Learn more about ADUs & building permits
Background reading on accessory dwelling units, building permits, and how Igni turns Seattle permit records into leads.
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Informational only, not legal advice. Headline counts reflect all permits Igni has tracked for this jurisdiction; the table shows recent activity. Housing law changes — verify current statutes before relying on this.