DADU Builder in Seattle, WA
Seattle homeowners have a rare opportunity: some of the most DADU-friendly rules of any major U.S. city, sitting on top of one of its strongest rental markets. We design, permit, and build your backyard cottage — one accountable team, first concept to final inspection.
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Why Seattle Is Ideal for a DADU
Seattle has been loosening its backyard-cottage rules since 2019, and the latest updates (effective 2025–2026) make it dramatically easier to build here than in most cities:
- Two ADUs per lot in addition to your house — a backyard cottage plus a basement unit, or even two DADUs
- Up to 1,000 sq ft of cottage — 1,200 sq ft with 3+ bedrooms — with up to 250 sq ft of garage space not counted
- DADU height matches the main house — up to 32 feet in Neighborhood Residential zones
- No off-street parking required, anywhere in the city
- No owner-occupancy requirement — live on-site or don't
- DADUs can be sold separately as condos — a real equity option
Verified July 2026 against Seattle Municipal Code 23.42.022 and SDCI guidance. Every lot is different — we confirm what current code allows on your property during a free feasibility visit.
What Homeowners Use a Seattle DADU For
A detached backyard cottage in Seattle is a realistic, high-return project — whether you want rental income, a place for family, or flexible space that grows with you:
Rental income
Long- or short-term income in a city where rents are high and demand is constant.
Multigenerational living
Keep family close — aging parents or adult children — with privacy on both sides.
Home office or studio
A quiet, dedicated workspace separate from the main house, steps from your door.
Future flexibility
Guest house today, rental tomorrow — space that grows and changes with you.
Our Design-Build Process
One accountable team from first sketch to final inspection — no juggling separate architects, permit expeditors, and contractors.
- 1. Consultation & feasibility — we evaluate your lot and what Seattle's code allows
- 2. Design — a DADU shaped to your property, budget, and goals
- 3. Permitting — we prepare and manage your SDCI submittals through the Seattle Services Portal
- 4. Construction — one team, clear milestones, steady communication
- 5. Rental- or family-ready — inspections handled, ready to use
Seattle DADU Questions, Answered
How many DADUs can I build on my Seattle lot?
Seattle allows two accessory dwelling units per lot in addition to your main house — in any combination. That could be one backyard cottage (DADU) plus a basement unit, or even two detached units. We confirm what your specific lot supports during feasibility.
What are the size and height limits for a Seattle DADU?
A Seattle DADU can have up to 1,000 square feet of gross floor area with up to two bedrooms, or up to 1,200 square feet with three or more bedrooms — and up to 250 square feet of attached garage doesn’t count. Height limits now match the main house: up to 32 feet in Neighborhood Residential zones.
Does Seattle require parking or owner occupancy for a DADU?
No to both. Seattle requires no off-street parking for ADUs anywhere in the city, and there is no requirement that the owner live on the property. You can rent out the main house, the DADU, or both.
Can I sell my Seattle DADU separately as a condo?
Yes. Seattle’s code explicitly allows a DADU to be sold as a condominium unit — which turns a backyard cottage into a genuine equity play, not just a rental. Our financing team can walk you through how condo-izing works.
What permits does a Seattle DADU need?
A new DADU needs an SDCI construction permit (plus electrical and plumbing permits), applied for through the Seattle Services Portal. SDCI’s pre-approved DADU standard plans can shorten plan review — and we prepare and manage the entire submittal for you.
Start Your Seattle DADU
Let’s talk through what’s possible on your lot. Schedule a free consultation and we’ll give you a clear, honest assessment.