Seattle ADU & DADU permit timeline and tracker
How long ADU and DADU permits actually take, plus every accessory dwelling unit permit across Seattle by year, neighborhood, and status. Compare attached ADUs with detached backyard cottages, and see where new small-scale housing activity is concentrating.
These are matching permit records, not a count of guaranteed completed dwellings. One property or project can have multiple related permits.
Source data updated through Oct 2, 2026.
How long does an ADU permit take in Seattle?
Detached units take longer: the median DADU runs 140 days from application to issuance against 106 days for an attached ADU. Averages run higher than medians — 136 days (ADU) and 153 days (DADU) — because a small number of long reviews pull the average up.
How long each step takes
- Application — the permit is filed with the Seattle Department of Construction and Inspections. 472 ADU and 1,449 DADU permits in this dataset have an application date.
- Review — plans go through SDCI review, including applicant correction cycles where published. 79% of applied ADU permits and 82% of applied DADU permits reach issuance.
- Issuance — the permit is issued. Median 106 days after application for ADUs and 140 days for DADUs.
- Completion — construction finishes and the permit is marked complete. 32% of issued ADU permits and 30% of issued DADU permits are marked complete, with a median of 233 days (ADU) and 286 days (DADU) from issuance.
Average application → issuance time by year
| Year | Type | Issued permits | Average days |
|---|---|---|---|
| 2024 | ADU | 60 | 82 days |
| 2024 | DADU | 186 | 89 days |
| 2025 | ADU | 207 | 127 days |
| 2025 | DADU | 738 | 156 days |
| 2026 | ADU | 108 | 183 days |
| 2026 | DADU | 264 | 190 days |
Grouped by issue date; partial years reflect records ingested so far. Years with a handful of dated permits are noisier than recent full years.
ADU and DADU permits by year
Grouped by issue date when available, otherwise application date.
Seattle neighborhoods with the most ADU activity
Recent Seattle ADU and DADU permits
| Permit | Type | Address | Neighborhood | Status | Value | Date |
|---|---|---|---|---|---|---|
| 7136568-CN | DADU | 6931 B FLORA AVE S, SEATTLE, WA | Georgetown | active | $80K | Sep 30, 2026 |
| 7163915-CN | DADU | 214 NW 140TH ST, SEATTLE, WA | Broadview | pending | $87K | Sep 24, 2026 |
| 7128603-CN | ADU | 336 25TH AVE E, SEATTLE, WA | Other Seattle | active | $658K | Sep 22, 2026 |
| 7123339-CN | DADU | 4829 49TH AVE SW, SEATTLE, WA | West Seattle | active | $122K | Sep 22, 2026 |
| 7130606-CN | DADU | 9044 9TH AVE SW, SEATTLE, WA | White Center | pending | $193K | Sep 22, 2026 |
| 7155660-CN | DADU | 9044 9TH AVE SW, SEATTLE, WA | White Center | completed | $201K | Sep 22, 2026 |
| 7163168-CN | ADU | 12707 1ST AVE NW, SEATTLE, WA | Broadview | completed | $384K | Sep 21, 2026 |
| 7163169-CN | ADU | 12707 1ST AVE NW, SEATTLE, WA | Broadview | completed | $384K | Sep 21, 2026 |
| 7112161-CN | DADU | 2808 E COLUMBIA ST, SEATTLE, WA | Central District | active | $452K | Sep 17, 2026 |
| 7099617-CN | DADU | 10236 A 56TH AVE S, SEATTLE, WA | Rainier Beach | active | $338K | Sep 17, 2026 |
| 7157712-CN | DADU | 5511 22ND AVE S, SEATTLE, WA | Other Seattle | active | $186K | Sep 16, 2026 |
| 7138650-CN | DADU | 723 B N 97TH ST, SEATTLE, WA | Greenwood | active | $303K | Sep 14, 2026 |
| 7132331-CN | DADU | 723 A N 97TH ST, SEATTLE, WA | Greenwood | active | $283K | Sep 14, 2026 |
| 7120276-CN | DADU | 10241 65TH AVE S, SEATTLE, WA | Rainier Beach | active | $150K | Sep 13, 2026 |
| 7124300-CN | ADU | 13726 41ST AVE NE, SEATTLE, WA | Lake City | active | $543K | Sep 11, 2026 |
| 7161421-CN | DADU | 14047 MERIDIAN AVE N, SEATTLE, WA | Haller Lake | completed | $222K | Sep 11, 2026 |
| 7161422-CN | DADU | 14047 MERIDIAN AVE N, SEATTLE, WA | Haller Lake | completed | $181K | Sep 11, 2026 |
| 7119817-CN | ADU | 5946 B 47TH AVE SW, SEATTLE, WA | West Seattle | active | $292K | Sep 9, 2026 |
| 7119819-CN | ADU | 5946 C 47TH AVE SW, SEATTLE, WA | West Seattle | active | $292K | Sep 9, 2026 |
| 6700444-CN | DADU | 4727 23RD AVE SW, SEATTLE, WA | West Seattle | active | $533K | Sep 9, 2026 |
ADU vs. DADU
ADU is the broader term for an accessory dwelling unit associated with a primary home. It can be inside, attached to, or converted from part of an existing structure.
DADU means detached accessory dwelling unit. In Seattle records it may also appear as a detached ADU or backyard cottage.
How the tracker works
Building Seattle searches public permit descriptions for explicit ADU terminology, classifies detached projects separately, and aggregates results by year and neighborhood. A permit mentioning both attached and detached units is classified as DADU.
Declared permit values and housing-unit fields are presented as reported and may be incomplete or revised during review.
Using ADU permit activity
Homeowners can see the kinds of projects moving through Seattle review. Contractors and designers can identify neighborhoods with sustained accessory-dwelling demand. Researchers can track how small-scale infill contributes to Seattle's housing pipeline.
Raw tracker data is available at /api/adu-dadu. Source records come from Seattle Department of Construction and Inspections permit data.