A backyard cottage with the permit waiting months cut to weeks.
The slowest part of building a DADU is the permit. Seattle's pre-approved plan program (ADUniverse) and similar programs in Kirkland and Renton can drop permit review from 4–8 months to 2–6 weeks — on a clean lot, with a plan the city has already vetted.
Is this you?
You want a real backyard cottage, but the timeline scares you — friends warn that permits “take a year” and your life will be on hold. You don’t need a one-of-a-kind custom design; you want a good, code-compliant unit built as fast as the city allows. That’s exactly what a pre-approved plan is for.
This format fits if you want to:
- Start collecting rent or housing family months sooner than a custom build.
- Skip $10K+ in architectural fees by adopting a plan the city has already reviewed.
- Build on a relatively standard lot — flat, on public sewer, no critical-area overlays.
What’s included — and what’s not
| Included | Not included |
|---|---|
| Plan selection + site adaptation from the city’s catalog | The land — you already own it |
| Foundation, full vertical build, kitchen, bath, HVAC | Heavy custom redesign of the pre-approved plan |
| Permit package + submittal on the fast-track path | Major utility upgrades beyond a standard connection |
| Standard utility connection + inspections | Geotech / slope work if the lot turns out to need it |
| Energy-code-compliant envelope | Furniture, appliances above standard, extra landscaping |
Published price range
A pre-approved plan saves you time and design fees — it doesn’t change what concrete, framing, and finishes cost. All-in covers the full project minus the land. Standard finish, 2025–26 King County ranges.
| Size | Vertical build | All-in (standard) |
|---|---|---|
| 500 sf studio / 1BR | ~$145K–$200K | $200K–$280K |
| 650 sf 1BR | ~$185K–$260K | $260K–$365K |
| 800 sf 1–2BR | ~$230K–$325K | $320K–$450K |
This is a planning range from real project data, not a bid. Your number depends on site conditions, finish level, and design. We confirm an exact, fixed-scope price on a real quote.
How it works
- Feasibility — confirm the lot is clean enough for the fast-track (flat, sewer, no ECA / shoreline overlay).
- Plan selection — pick from the city’s pre-approved catalog and match it to your lot.
- Site adaptation + submittal on the pre-approved path.
- Permit review — typically 2–6 weeks instead of 4–8 months.
- Build + inspections + utility connection, then move-in or rent.
City notes
Seattleruns the pre-approved program through ADUniverse, with permit review cited at 2–6 weeks versus 4–8 months for a custom DADU. Kirkland has its own pre-approved plan set — and a more generous 1,200 sf cap, the largest in King County. Renton and a growing list of cities offer plan-library or expedited paths too. Only a small share of King County builders use these programs, which is why most homeowners never hear the timeline can be this short. Where a city has no program, a custom DADU is the path — see our custom DADU page.
Seattle cites 2–6 weeks for permit review on a pre-approved DADU plan, versus 4–8 months for a custom design. That's the review window on a clean lot. Total project time still includes construction and utility connection, but you save months at the front and roughly $10K in architectural fees.
