What we count
Every number in this app comes from the City of Seattle's public building permit records. This page explains exactly which permits are counted, what's left out and why, with live counts.
Every building permit that adds housing units, whatever the City's permit class. That includes mixed-use buildings the City classes as “Commercial”. Right now that's 29,741 permits adding 219,597 units.
Units are credited to the date each permit reaches a milestone: applied, issued or completed. “Completed” is the City's completion date, roughly the final inspection. It can lag move-in by weeks to months, so the most recent months are provisional.
Completions are shown net: units added minus units removed. Units removed come from demolition permits (10,361 units) and from building permits that remove units, for example by combining apartments (4,106 units).
A demolition is counted on the date it was issued, not completed. Demolitions usually happen soon after issue, but the City often records their completion much later: the median gap is about 10 months, and in early 2017 hundreds of demolitions from 2007–2011 were closed out at once. Dating by completion would put those removals in the wrong year. Demolitions that were cancelled, or issued and then expired, aren't counted (3,257 units). The permit list can show units added, removed or net.
The City links permits for the same development through a “development site”. We group those into projects: 25,983 projects, of which 2,261 span more than one building permit (for example, a row of townhouses permitted building by building).
Units are still counted per permit, as each building reaches its milestone. Counts of developments, and the reliability rule below, use projects, so 45 townhouse permits on one site count as one development.
| Left out | Why | Permits | Units |
|---|---|---|---|
| Pre-application proposals | In the City's system but not formally applied for. Many are long abandoned, and the City publishes no dates for them. | 1,248 | 21,901 |
| Building permits that add no units | Alterations, commercial work, garages and so on. | 125,457 | — |
| Units “added” on demolition permits | Demolition permits sometimes report the units of the replacement building. Those are counted on the building permit instead, to avoid double counting. | 16,135 | 36,256 |
| Shoring and excavation permits | Site-preparation permits that restate the units of the building they dig the hole for, often without being linked to it. Those units are counted once, on the building permit. | 18 | 3,752 |
| Repeated development totals | A few multi-building developments list the whole development's units on every building's permit. Where three or more unlinked permits on the same street, applied for on the same day, each list the same 50+ units, we count the units once. | 23 | 5,474 |
| Permits without a location | Counted in citywide totals but not in any area, map or radius view. | 104 | 1,083 |
| Permits the City has removed | No longer in the City's dataset; kept for history only. | 0 | — |
Roof, grading and environmental exemption permits aren't imported at all; they never add housing.
- Pipeline
- Not finished and not dead: Active, Additional Info Requested, Application Completed, Awaiting Information, Corrections Required, Corrections Submitted, Initiated, Issued, Pending, Phase Issued, Ready for Intake, Ready for Issuance, Reviews Completed, Reviews In Process, Scheduled, Scheduled and Submitted.
- Done
- Construction finished: Completed, Closed, Approved to Occupy, Inspections Completed.
- Lapsed
- Issued, then expired: 1,973 permits, 11,475 units. Seattle construction permits expire 18 months after issuance unless renewed. The project may have been abandoned, may have been finished without a recorded final inspection, or may have continued under another permit. The data can't tell which, so lapsed units are never counted as built or as dead.
- Dead
- Won't be built under this permit: Canceled, Withdrawn, Denied, or Expired before ever being issued.
If the City introduces a status not listed here, the nightly update fails rather than guessing.
Each permit gets one type. We use the City's recorded dwelling type when there is one. A new house built together with ADUs counts as ADU/DADU. Multifamily buildings are split by units added: small (under 20), mid-size (20–149) and large (150+).
The City has largely stopped recording dwelling types (2022: 81%, 2023: 83%, 2024: 72%, 2025: 9%, 2026: 0% of applications), so recent types are mostly inferred from the housing category, permit class, unit count and description. To check the inference, we hide the City's type on 7,402 permits from 2018–2023 and compare: it matches for 92% of permits and 97% of units.
| Type | Units checked | Found (recall) | Correct when guessed (precision) |
|---|---|---|---|
| Detached house | 2,131 | 71% | 93% |
| ADU/DADU | 6,049 | 96% | 92% |
| Townhouse/rowhouse | 7,818 | 93% | 95% |
| Small multifamily | 772 | 83% | 62% |
| Mid-size multifamily | 13,505 | 100% | 99% |
| Large multifamily | 21,135 | 100% | 100% |
Detached houses are the weakest: the inference tends to label them as townhouses or ADUs, so recent detached-house counts are likely understated.
Share built follows each permit from the year it was applied for: the units it adds count as built, still in progress, lapsed or dead according to its current status. Share built is built units divided by all units applied for that year, leaving out lapsed permits because their outcome is unknown.
Time per stage is measured per project, so a site permitted building by building counts once: from its first application to its last building permit being issued, and from that issue to its last building being completed. Medians come with the middle half of projects (25th–75th percentile).
Recent application years are provisional. An application year is provisional until 90% of past projects of that type would have finished. Until then its share built will keep rising, and its durations are biased short because only the fastest projects have finished.
City review vs. applicant corrections uses the City's own split of plan-review time on each project's main permit. The City has only recorded it for applications since 2018.
Stalled projects are pipeline projects that have spent longer in their current stage than 90% of past projects of the same type (applications from the last 10 years), or whose issued permit expires within 90 days.
Every total shows how many projects are behind it. Two rules apply everywhere:
- If one project makes up more than 50% of the units, the total is flagged, because it mostly reflects a single development.
- Percent changes, medians, shares and rankings aren't computed when fewer than 10 projects are behind them. Raw counts are always shown.
The threshold of 10 projects is provisional and will be calibrated against how often small-sample changes reverse the following year.
- The City uses 1900-01-01 as a placeholder for unknown dates. We treat it as missing.
- Completion dates are sometimes recorded late, so the last few months tend to rise after the fact.
- Coordinates outside Seattle are treated as missing.