Seattle DADU & ADU Feasibility
Know what your Seattle lot may allow — before you spend thousands.
The complete 2026 reference for Seattle homeowners evaluating a DADU — what's allowed, what blocks projects, and what to check before you commit to architects, permits, or contractors.
Preliminary planning report only. Not permit approval, legal advice, or official City of Seattle determination.
Seattle DADU Pro Guide
Before you hire an architect, pull a permit, or talk to a builder — understand exactly what Seattle's current rules say about your lot. Updated for 2026 Seattle law.
- What Seattle currently allows — and what actually determines if a DADU fits your lot
- Setbacks, size limits, height, and how much you can build
- Trees and site constraints that can block or reshape your project
- Sewer, water, and electrical — what to check before you commit
- Pre-approved plans vs. custom design — pros, cons, and when each makes sense
- The full permit and build process, step by step
- What to do after you build — rent, sell separately, or hold
- The 13 most common mistakes Seattle homeowners make
- Self-study checklist + site feasibility scoring template
Educational & preliminary. Not legal, architectural, or engineering advice.
Customized Feasibility Report
A fully customized, property-specific Seattle DADU feasibility report — your address run through every factor, with a tailored analysis and next steps.
- Your parcel's zoning, lot coverage, and unit eligibility
- Measured setbacks and a buildable-envelope estimate
- Tree tiers and critical areas mapped to your site
- Sewer, water, and electrical capacity flags
- A recommended permit path with realistic timelines
Pricing and availability to be announced.
Read the free guides first.
Two in-depth guides that show exactly what Seattle DADU feasibility involves. Read them free, no email required. If you want the complete picture, the Pro Guide goes deeper.
Seattle Pre-Approved DADU Standard Plans That Can Save You Weeks on Permitting
Pre-approved doesn't mean pre-feasible. Here's the complete fact-checked guide to Seattle's standard DADU plans, lot eligibility, permit timelines, and the site risks that still matter.
Read free →
Can I Build a DADU in Seattle? 2026 Homeowner Checklist
Zoning is only the first question. Here's the full checklist — setbacks, trees, utilities, drainage, access, and the 7 things that actually decide DADU feasibility.
Read free →By neighborhood
What does your part of Seattle actually allow?
Lot sizes, slope, landslide ground and tree canopy vary enormously across the city. These profiles are measured from City of Seattle open data, one neighborhood at a time.
The free guides cover the big picture. The Seattle DADU Pro Guide has the complete setback rules, utility checklists, tree tiers, permit roadmap, 13 common mistakes, and a self-study feasibility scoring template.