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 2,851 residential and building permits in Seattle, WA — including 421 classified accessory-dwelling-unit (ADU) filings. The most active ZIP is 98103. The most recent filing Igni tracked was Oct 31, 2026. All records come from data.seattle.gov (Socrata), an official government open-data feed, and are refreshed continuously.
2851
Permits tracked
421
ADU permits
26
Distinct ZIP codes
Oct 31, 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 |
|---|---|---|---|---|
| 98107 | Commercial | — | $522,273 | Apr 1, 2026 |
| 98199 | Residential | — | $473,176 | Oct 30, 2026 |
| 98112 | Commercial | — | $25,000 | Oct 31, 2026 |
| 98177 | Residential | — | $370,497 | Jan 20, 2026 |
| 98177 | Residential | — | $765,767 | Jan 20, 2026 |
| 98177 | Residential | — | $379,563 | Jan 20, 2026 |
| 98108 | Residential | — | $347,642 | Apr 22, 2026 |
| 98108 | Residential | — | $422,909 | Apr 22, 2026 |
| 98108 | Residential | — | $420,722 | Apr 22, 2026 |
| 98125 | Residential | — | $45,000 | May 6, 2026 |
| 98108 | Residential | — | $335,508 | May 20, 2026 |
| 98108 | Residential | — | $234,759 | May 20, 2026 |
| 98108 | Residential | — | $234,759 | May 20, 2026 |
| 98108 | Residential | — | $338,116 | May 21, 2026 |
| 98108 | Residential | — | $329,547 | May 21, 2026 |
| 98112 | Residential | — | $81,197 | Jun 30, 2026 |
| 98109 | Residential | — | $801,945 | Jul 7, 2026 |
| 98109 | Commercial | — | $360,000 | Jul 22, 2026 |
| 98119 | Commercial | — | $150,000 | Aug 27, 2026 |
| 98112 | Residential | — | $2,000 | Oct 29, 2026 |
Top ZIP codes by recent activity
ADU types in the recent set
Permit activity in Seattle
Igni counted 6,352 permits issued in Seattle over the last 12 months (Oct 2025 – Sep 2026) — up 2.1% on the 6,220 in the 12 months before. The forecast expects about 3,033 over the next 6 months.
Forecast: seasonal naive, typical error ±8% in backtests one to six months ahead. How we forecast
| Permit type | Last 12 months | Year over year | Forecast, next 6 months |
|---|---|---|---|
| All permits | 6,352 | Up 2.1% | ≈ 3,033 |
| Residential building | 4,999 | Up 4.6% | ≈ 2,430 |
| Commercial building | 1,353 | Down 6.0% | ≈ 678 |
| Trade (electrical, plumbing, mechanical) | 0 | — | — |
| ADU | 548 | Down 47.3% | — |
Monthly figures
| Month | Permits | 10th–90th percentile |
|---|---|---|
| Oct 2023 | 455 | — |
| Nov 2023 | 415 | — |
| Dec 2023 | 386 | — |
| Jan 2024 | 458 | — |
| Feb 2024 | 485 | — |
| Mar 2024 | 545 | — |
| Apr 2024 | 545 | — |
| May 2024 | 513 | — |
| Jun 2024 | 513 | — |
| Jul 2024 | 484 | — |
| Aug 2024 | 481 | — |
| Sep 2024 | 489 | — |
| Oct 2024 | 504 | — |
| Nov 2024 | 384 | — |
| Dec 2024 | 446 | — |
| Jan 2025 | 459 | — |
| Feb 2025 | 414 | — |
| Mar 2025 | 574 | — |
| Apr 2025 | 607 | — |
| May 2025 | 623 | — |
| Jun 2025 | 616 | — |
| Jul 2025 | 543 | — |
| Aug 2025 | 532 | — |
| Sep 2025 | 518 | — |
| Oct 2025 | 530 | — |
| Nov 2025 | 377 | — |
| Dec 2025 | 527 | — |
| Jan 2026 | 476 | — |
| Feb 2026 | 409 | — |
| Mar 2026 | 651 | — |
| Apr 2026 | 636 | — |
| May 2026 | 524 | — |
| Jun 2026 | 589 | — |
| Jul 2026 | 565 | — |
| Aug 2026 | 561 | — |
| Sep 2026 | 507 | — |
| Oct 2026 (forecast) | ≈ 541 | 437–582 |
| Nov 2026 (forecast) | ≈ 385 | 310–415 |
| Dec 2026 (forecast) | ≈ 538 | 422–566 |
| Jan 2027 (forecast) | ≈ 486 | 378–512 |
| Feb 2027 (forecast) | ≈ 418 | 325–439 |
| Mar 2027 (forecast) | ≈ 665 | 518–701 |
Counts are permits issued per calendar month as Seattle publishes them to its open-data feed — not a complete census; a change in what the city publishes moves them too. The current month is left out, and the most recent months are provisional. A forecast is a statistical estimate with a range, not a prediction for any project. Informational only.
How long do permits take in Seattle?
Based on 16,722 Seattle permits applied for between Nov 2023 and Aug 2026, the typical (median) permit was issued 66 days after application, and the middle half of permits took 9–178 days. One in ten took longer than 439 days.
| Permit type | Median | Typical range | Permits |
|---|---|---|---|
| All permits | 66 days | 9–178 days | 16,722 |
| Residential building | 71 days | 5–183 days | 12,841 |
| Commercial building | 56 days | 20–145 days | 3,881 |
| ADU | 154 days | 92–260 days | 2,156 |
Typical, not guaranteed: individual permits vary with project scope, application completeness and plan-review workload. Days are calendar days from application to issuance; applications still pending are counted as not-yet-issued rather than dropped. Informational only, not legal advice. How we calculate approval times.
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.
Seattle permit data — FAQ
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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.