Residential ADU and addition permits in Seattle, WA
27 residential ADU and addition permits issued by Seattle (electrical), Seattle (trade: mechanical/plumbing), the 8 weeks ending Oct 16, 2026. Oct 16, 2026 is the latest issue date the source has published.
Quick answer. In the 8 weeks ending Oct 16, 2026, 27 residential ADU and addition permits were issued in Seattle, WA, according to public records from Seattle (electrical), Seattle (trade: mechanical/plumbing). The busiest ZIP codes were 98118 (11 permits), 98117 (3 permits), 98119 (2 permits). The median declared value was $16,500 across 11 permits that list one. The latest permit date published is Oct 16, 2026.
What an ADU and addition permit means in Seattle
A residential ADU or addition permit is a new unit or more square footage on an existing home. For an ADU builder or addition contractor it shows where lots are being built out, and the subs those jobs need.
In Seattle, permits were issued on 16 different days in the window; the most recent were Oct 16, 2026, Oct 13, 2026, Oct 12, 2026. The busiest ZIPs were 98118 (11), 98117 (3), 98119 (2).
By residential ADU and addition permit count, Seattle ranks #29 of the 49 ADU and addition pages on this site and #2 of 5 in WA.
- Mail the neighbors of each ADU.
- Pitch trades to the builders pulling the most permits.
- Track declared values by ZIP.
Other work on the same permits
Share of these 27 permits whose type or description also matches another trade. These are the follow-on and partner trades on Seattle jobs.
- electrical: 8 permits (30%)
- HVAC: 6 permits (22%)
- battery storage: 1 permits (4%)
- solar: 1 permits (4%)
Weekly trend
Permits per 7-day period, ending Oct 16, 2026. n/c = not collected yet (before our pipeline started pulling this source). It is not zero. Striped bars are partly collected weeks.
Top permit types
| Permit type / subtype | Permits | Share |
|---|---|---|
| Single Family/Duplex | 11 | 41% |
| N/A | 8 | 30% |
| Multifamily | 8 | 30% |
Busiest ZIP codes
| ZIP | Permits | Share | 8-wk avg / week |
|---|---|---|---|
| 98118 | 11 | 41% | 1.50 |
| 98117 | 3 | 11% | 0.50 |
| 98119 | 2 | 7% | 0.25 |
| 98125 | 2 | 7% | 0.25 |
| 98144 | 2 | 7% | 0.25 |
8-wk avg / week is the trailing 8-week weekly average we quote in coverage checks for that ZIP and trade. It counts every source in the ZIP and includes permits with unknown use, so it can be higher than this page's residential count.
Type stated in the permit
| Type | Permits | Share |
|---|---|---|
| ADU | 26 | 96% |
Parsed from the permit's own type and work text. A permit can state more than one; many state none.
Sample rows
Anonymized: street address, permit number and any names removed. Subscribers get the full row with address, permit number and source link.
| Issued | ZIP | Permit type | Scope | Type | Declared value |
|---|---|---|---|---|---|
| 2026-10-16 | 98117 | N/A | electrical + addition/ADU | ADU | n/a |
| 2026-10-10 | 98199 | Single Family/Duplex | HVAC + addition/ADU | ADU | $5,500 |
| 2026-10-02 | 98115 | Single Family/Duplex | HVAC + addition/ADU | ADU | $9,000 |
| 2026-09-15 | 98146 | Single Family/Duplex | electrical + addition/ADU | ADU | $39,508 |
| 2026-09-11 | 98118 | Multifamily | addition/ADU | ADU | n/a |
| 2026-09-11 | 98118 | Multifamily | addition/ADU | ADU | n/a |
Source
- Seattle (electrical): Permit records on cos-data.seattle.gov (dataset c4tj-daue), published by Seattle (electrical). Source dataset. Collected window(s): Aug 22, 2026 – Oct 16, 2026. Last pulled Oct 18, 2026.
- Seattle (trade: mechanical/plumbing): Permit records on cos-data.seattle.gov (dataset c87v-5hwh), published by Seattle (trade: mechanical/plumbing). Source dataset. Collected window(s): Aug 22, 2026 – Oct 16, 2026. Last pulled Oct 18, 2026.
Metric: Residential = the source marks the permit's use as residential (permits with commercial or unknown use are not counted). ADUs & Additions = the permit's type or work description matches the Curbside Signal ADU and addition rules. Counts exclude void or cancelled permits. Dates are the jurisdiction's permit issue date. Records are deduplicated on source and permit number. How we count. Part of the Seattle-Tacoma-Bellevue, WA metro: every trade × city page there.
The honest limit. A permit usually means the job is already sold. We say that up front. The value is what happens around it:
- Neighbor marketing around active jobs: same-age houses on the same street.
- Cross-trade follow-on demand: new roof → solar, gutters, insulation; remodel → HVAC, electrical, landscaping, pool; new build → pest, security, landscaping.
- Competitor intelligence: which contractors pull permits where (where the jurisdiction publishes it), and who to recruit as subs.
- Early-stage projects for commercial trades and GC subs.
Follow-on: ADUs and additions drive HVAC, electrical, plumbing, solar and landscaping work.
Other trades in Seattle, WA
Residential permits in the same window, by trade.
Questions
How many residential ADU and addition permits were issued in Seattle, WA recently?
27 residential ADU and addition permits in the public records we pulled, the 8 weeks ending Oct 16, 2026. Source: Seattle (electrical), Seattle (trade: mechanical/plumbing).
Which Seattle ZIP codes have the most ADU and addition permits?
98118 (11 permits), 98117 (3 permits), 98119 (2 permits), by residential ADU and addition permit count the 8 weeks ending Oct 16, 2026. 10 ZIP codes had at least one permit.
What is the median declared value of a residential ADU and addition permit in Seattle?
$16,500, across 11 permits that list a valuation. Declared values are what the applicant stated on the permit, not the contract price.
How do I get the Seattle ADU and addition permit list, and what does it cost?
Request a free sample for your ZIPs first. ZIP Pack is $29/mo for one trade and up to 5 ZIPs every Monday; Metro Feed is $99/mo for a whole metro and up to 3 trades, with daily alerts. Guarantee on every package: If a weekly file is late or missing, that month is free. If a month delivers under half the 8-week average permit count for your ZIPs and trade, the next month is free.
Seattle ADU and addition leads, every Monday
Send your trade and ZIP codes. We'll reply with a real sample from the public records we pull, or tell you plainly that we don't cover you yet.