ADU & DADU builder in Seattle.
Tight urban infill and alley-load DADUs — we know SDCI's review process cold and permit the toughest lots in the city. DIGS designs, permits and builds custom ADUs, DADUs and homes across Seattle and the surrounding Greater Seattle area — owner-led from the first call through final inspection.
Every trade your Seattle build needs — one team.
ADU & DADU Construction
Experts in constructing Attached and Detached Accessory Dwelling Units for versatile living spaces.
Site Development
Land preparation for construction, including grading, excavation, and utility installation.
Excavation
Digging and removing earth or rocks to prepare the construction site.
Groundwork
Initial preparation of land, including excavation and foundational activities.
Concrete & Foundations
Building strong foundations with high-quality concrete for durable construction projects.
Civil Work
Construction activities related to infrastructure, such as roads, bridges, and utilities.
A local builder who knows Seattle.
Headquartered in Monroe, WA 98272, DIGS has spent 37+ years building across King and Snohomish County. We know the local zoning, critical-area rules, setbacks and how Seattle reviews and permits — so your project never stalls at an unfamiliar counter.
Experienced Team
37+ years of local building, with deep familiarity with Seattle, King and Snohomish County code.
Customizable Designs
Ready-made plans you can adapt — or a fully custom design drawn to your lot and lifestyle.
Clear, Honest Pricing
Line-item estimates, no hidden fees, and no scope changes without your sign-off in writing.
Honest Communication
Real-time project visibility and a builder who is always reachable by phone, email or text.
ADU & DADU guides for Seattle homeowners
- 2- and 3-Bedroom ADU Floor Plans: What Fits in 700, 800, 1,000 and 1,200 sq ft →
- Building an ADU Above a Garage in Seattle: The Carriage-House Option →
- Building a DADU in North Seattle: Northgate, Lake City and Maple Leaf →
- Getting Power to a DADU: Seattle City Light, Subpanels and Separate Meters →
- Two ADUs or a Fourplex? What You Can Build on a Seattle Lot →
- How Big Can a DADU Be in Seattle? →
- Do You Need a Permit to Build a DADU in Seattle? →
- Seattle's Pre-Approved DADU Plans: Are They Worth It? →
- Can a Tree Stop Your DADU? Seattle's Tree Protection Rules →
- Drainage, Excavation and Site Work on a Backyard DADU →
- Do You Need Fire Sprinklers in a Seattle DADU? →
- ADU Parking Rules in Seattle: What You Need to Know →
- How Much Does It Cost to Build a DADU in Seattle? →
Also building ADUs & DADUs near Seattle
Bellevue, WA · Redmond, WA · Kirkland, WA · Sammamish, WA · Bothell, WA · Kenmore, WA · Woodinville, WA · Shoreline, WA · Lynnwood, WA · Everett, WA · Snohomish, WA · Monroe, WA · Lake Stevens, WA · Mukilteo, WA
Building an ADU in Seattle — the basics.
Who issues the ADU or DADU permit in Seattle, WA?
For an address inside Seattle city limits, the Seattle Department of Construction and Inspections (SDCI) reviews and issues the permit under the city's own ADU code. Unincorporated parcels nearby go through King County instead, under different rules, size limits and fees — so the jurisdiction line is the first thing a feasibility study confirms.
How much does a DADU cost to build in Seattle?
A fully permitted, professionally built detached ADU in Seattle and the surrounding Greater Seattle area typically runs $375,000 to $600,000+ all-in — design, permitting, site work and construction. Where a specific lot lands in that range is decided by site conditions: slope, soils, utility distances and tree or critical-area constraints.
Does DIGS build ADUs and DADUs in Seattle?
Yes. DIGS Construction and ADU Builder is headquartered in Monroe, WA and has built across King and Snohomish County since 1989, including Seattle. Owner Eric Dexter leads every project personally from the first call through final inspection, and quotes are all-in with site work included.
More answers in the ADU & DADU FAQ, or estimate a Seattle project with the ADU cost calculator.
“Eric and his team did a fantastic job clearing out some land to make it usable and prepping areas just how we needed them. The results look great.”
Building in Seattle? Let's talk.
Tell us about your lot and your goals. Eric follows up personally — the same person from the first call through final inspection. No pressure, no obligation.
- Owner-led — 37+ years, 100+ homes built
- Clear, line-item pricing · no hidden fees
- Serving Seattle, King & Snohomish County